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The face is an important site for the identification of others and conveys significant social information. Probably because of the importance of its role in social interaction, psychological processes involved in face perception are known to be present from birth, complex, involve large and widely distributed areas in the brain and can be selectively damaged to cause a specific impairment in understanding faces known as [[prosopagnosia]].
 
The face is an important site for the identification of others and conveys significant social information. Probably because of the importance of its role in social interaction, psychological processes involved in face perception are known to be present from birth, complex, involve large and widely distributed areas in the brain and can be selectively damaged to cause a specific impairment in understanding faces known as [[prosopagnosia]].
   
==Development of face perception==
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==Development==
While there is no question that the majority of face perception skills developed by adults are not present in babies, there is evidence of an innate tendency to pay attention to faces from birth. It is known that early perceptual experience is crucial to the development of [[visual perception]] and this orienting response undoubtedly encourages the rapid development of face specific skills such as the ability to identify friendly others and relatively complex pre-verbal communication. By two months of age face perception has developed so specific areas of the brain are known to be activated by viewing faces.<sup>[[Face perception#References|1]]</sup>
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From [[birth]], infants possess rudimentary facial processing capacities. Infants as young as two days of age are capable of mimicking the [[facial expressions]] of an adult, displaying their capacity to note details like mouth and eye shape as well as to move their own muscles in a way that produces similar patterns in their faces.<ref>{{cite journal| author = [[Tiffany M. Field]], [[Robert Woodson]], [[Reena Greenberg]], [[Debra Cohen]] |title=Discrimination and imitation of facial expressions by neonates|journal=Science|date=8 October 1982|volume=218|issue=4568|pages=179–181|doi= 10.1126/science.7123230|url=http://www.sciencemag.org/content/218/4568/179| pmid = 7123230}}</ref> However, despite this ability, newborns are not yet aware of the emotional content encoded within facial expressions. Five-month olds, when presented with an image of a person making a [[fearful]] expression and a person making a [[happy]] expression, pay the same amount of attention to and exhibit similar event-related potentials for both. When seven-month-olds are given the same treatment, they focus more on the fearful face, and their [[event-related potential]] for the scared face shows a stronger initial negative central component than the happy face. This result indicates an increased attentional and cognitive focus toward fear that reflects the [[threat]]-salient nature of the emotion.<ref>{{Cite journal | author = [[Mikko J. Peltola]], [[Jukka M. Leppanen]], [[Silja Maki]] & [[Jari K. Hietanen]] | title = Emergence of enhanced attention to fearful faces between 5 and 7 months of age | journal = [[Social cognitive and affective neuroscience]] | volume = 4 | issue = 2 | pages = 134–142 | year = 2009 | month = June | doi = 10.1093/scan/nsn046 | pmid = 19174536 | pmc = 2686224 }}</ref> In addition, infants’ negative central components were not different for new faces that varied in the intensity of an emotional expression but portrayed the same emotion as a face they had been habituated to but were stronger for different-emotion faces, showing that seven-month-olds regarded happy and [[sad]] faces as distinct emotive categories.<ref name="ReferenceA">{{Cite journal | title = Categorical representation of facial expressions in the infant brain | journal = [[Infancy : the official journal of the International Society on Infant Studies]] | volume = 14 | issue = 3 | pages = 346–362 | year = 2009 | month = May | doi = 10.1080/15250000902839393 | pmid = 20953267 | last1 = Leppanen | first1 = Jukka | last2 = Richmond | first2 = Jenny | last3 = Vogel-Farley | first3 = Vanessa | last4 = Moulson | first4 = Margaret | last5 = Nelson | first5 = Charles | pmc = 2954432}}</ref>
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The recognition of faces is an important neurological mechanism that an individual uses every day. Jeffrey and Rhodes<ref>{{cite journal|last=Jeffery|first=L.|coauthors=Rhodes, G.|title=Insights into the development of face recognition mechanisms revealed by face after effects.|journal=British Journal of Psychology|year=2011|volume=102|issue=4|pages=799–815|doi=10.1111/j.2044-8295.2011.02066.x}}</ref> said that faces "convey a wealth of information that we use to guide our social interactions."<ref>{{cite journal|last=Jeffery|first=L.|coauthors=Rhodes, G.|title=Insights into the development of face recognition mechanisms revealed by face aftereffects.|journal=British Journal of Psychology|year=2011|volume=102|issue=4|pages=799|doi=10.1111/j.2044-8295.2011.02066.x}}</ref> For example, emotions play a large role in our social interactions. The perception of a positive or negative emotion on a face affects the way that an individual perceives and processes that face. A face that is perceived to have a negative emotion is processed in a less holistic manner than a face displaying a positive emotion.<ref>{{cite journal|last=Curby|first=K.M.|coauthors=Johnson, K.J., & Tyson A.|title=Face to face with emotion: Holistic face processing is modulated by emotional state|journal=Cognition and Emotion|year=2012|volume=26|issue=1|pages=93–102|doi=10.1080/02699931.2011.555752}}</ref> The ability of face recognition is apparent even in early childhood. By age five, the neurological mechanisms responsible for face recognition are present. Research shows that the way children process faces is similar to that of adults, however adults process faces more efficiently. The reason for this may be because of improvements in memory and cognitive functioning that occur with age.<ref>{{cite journal|last=Jeffery|first=L.|coauthors=Rhodes, G.|title=Insights into the development of face recognition mechanisms revealed by face aftereffects.|journal=British Journal of Psychology|year=2011|volume=102|issue=4|pages=799–815|doi=10.1111/j.2044-8295.2011.02066.x}}</ref>
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Infants are able to comprehend facial expressions as [[social cues]] representing the feelings of other people before they have been alive for a year. At seven months, the object of an observed face’s apparent emotional reaction is relevant in processing the face. Infants at this age show greater negative central components to angry faces that are looking directly at them than elsewhere, although the direction of fearful faces’ gaze produces no difference. In addition, two ERP components in the posterior part of the brain are differently aroused by the two negative expressions tested. These results indicate that infants at this age can at least partially understand the higher level of threat from [[anger]] directed at them as compared to anger directed elsewhere.<ref name="Stefanie Hoehl & Tricia Striano 2008 1752–1760" /> At least seven months of age, infants are also able to use others’ facial expressions to understand their behavior. Seven-month olds will look to facial cues to understand the motives of other people in ambiguous situations, as shown by a study in which they watched an experimenter’s face longer if she took a toy from them and maintained a neutral expression than if she made a happy expression.<ref>{{Cite journal | author = [[Tricia Striano]] & [[Amrisha Vaish]] | title = Seven- to 9-month-old infants use facial expressions to interpret others' actions | journal = [[British Journal of Developmental Psychology]] | volume = 24 | pages = 753–760 | year = 2010 | doi = 10.1348/026151005X70319 | issue = 4 }}</ref> Interest in the social world is increased by interaction with the physical environment. Training three-month-old infants to reach for objects with [[Velcro]]-covered “sticky mitts” increases the amount of attention that they pay to faces as compared to passively moving objects through their hands and non-trained control groups.<ref>{{Cite journal | author = [[Klaus Libertus]] & [[Amy Needham]] | title = Reaching experience increases face preference in 3-month-old infants | journal = [[Developmental science]] | volume = 14 | issue = 6 | pages = 1355–1364 | year = 2011 | month = November | doi = 10.1111/j.1467-7687.2011.01084.x | pmid = 22010895 }}</ref>
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In following with the notion that seven-month-olds have categorical understandings of emotion, they are also capable of associating emotional prosodies with corresponding facial expressions. When presented with a happy or angry face, shortly followed by an emotionally-neutral word read in a happy or angry tone, their ERPs follow different patterns. Happy faces followed by angry vocal tones produce more changes than the other incongruous pairing, while there was no such difference between happy and angry congruous pairings, with the greater reaction implying that infants held greater expectations of a happy vocal tone after seeing a happy face than an angry tone following an angry face. Considering an infant’s relative [[immobility]] and thus their decreased capacity to elicit negative reactions from their parents, this result implies that experience has a role in building comprehension of facial expressions.<ref>{{Cite journal | author = [[Tobias Grossmann]], [[Tricia Striano]] & [[Angela D. Friederici]] | title = Crossmodal integration of emotional information from face and voice in the infant brain | journal = [[Developmental science]] | volume = 9 | issue = 3 | pages = 309–315 | year = 2006 | month = May | doi = 10.1111/j.1467-7687.2006.00494.x | pmid = 16669802 }}</ref>
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Several other studies indicate that early perceptual experience is crucial to the development of capacities characteristic of adult visual perception, including the ability to identify familiar others and to recognize and comprehend facial expressions.<ref name="Charles A. Nelson 2001 3–18">{{Cite journal | author = [[Charles A. Nelson]] | title = The development and neural bases of face recognition | journal = [[nfant and Child Development]] | volume = 10 | issue = 1–2 | pages = 3–18 | year = 2001 | month = March–June | doi = 10.1002/icd.239}}</ref> The capacity to discern between faces, much like language, appears to have a broad potential in early life that is whittled down to kinds of faces that are experienced in early life.<ref name="Charles A. Nelson 2001 3–18"/> Infants can discern between [[macaque]] faces at six months of age, but, without continued exposure, cannot at nine months of age. Being shown photographs of macaques during this three-month period gave nine-month-olds the ability to reliably tell between unfamiliar macaque faces.<ref>{{Cite journal | author = [[O. Pascalis]], [[L. S. Scott]], [[D. J. Kelly]], [[R. W. Shannon]], [[E. Nicholson]], [[M. Coleman]] & [[C. A. Nelson]] | title = Plasticity of face processing in infancy | journal = [[Proceedings of the National Academy of Sciences of the United States of America]] | volume = 102 | issue = 14 | pages = 5297–5300 | year = 2005 | month = April | doi = 10.1073/pnas.0406627102 | pmid = 15790676 | pmc = 555965}}</ref>
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The neural substrates of face perception in infants are likely similar to those of adults, but the limits of imaging technology that are feasible for use with infants currently prevent very specific localization of function as well as specific information from subcortical areas<ref name="Emi Nakato, Yumiko Otsuka, So Kanazawa, Masami K. Yamaguchi & Ryusuke Kakigi 2011 1600–1606">{{Cite journal | author = [[Emi Nakato]], [[Yumiko Otsuka]], [[So Kanazawa]], [[Masami K. Yamaguchi]] & [[Ryusuke Kakigi]] | title = Distinct differences in the pattern of hemodynamic response to happy and angry facial expressions in infants--a near-infrared spectroscopic study | journal = [[NeuroImage]] | volume = 54 | issue = 2 | pages = 1600–1606 | year = 2011 | month = January | doi = 10.1016/j.neuroimage.2010.09.021 | pmid = 20850548 }}</ref> like the [[amygdala]], which is active in the perception of facial expression in adults.<ref name="Charles A. Nelson 2001 3–18"/> In a study on healthy adults, it was shown that faces are likely to be processed, in part, via a retinotectal (subcortical) pathway.<ref>{{cite journal |author=Awasthi B, Friedman J, Williams, MA| title=Processing of low spatial frequency faces at periphery in choice reaching tasks|journal=Neuropsychologia | volume = 49 | issue = 7 | pages = 2136–41 | year = 2011 | doi = 10.1016/j.neuropsychologia.2011.03.003 |pmid=21397615}}</ref>
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However, there is activity near the [[fusiform gyrus]],<ref name="Emi Nakato, Yumiko Otsuka, So Kanazawa, Masami K. Yamaguchi & Ryusuke Kakigi 2011 1600–1606"/> as well as in occipital areas.<ref name="Stefanie Hoehl & Tricia Striano 2008 1752–1760">{{Cite journal
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| author = [[Stefanie Hoehl]] & [[Tricia Striano]] | title = Neural processing of eye gaze and threat-related emotional facial expressions in infancy | journal = [[Child development]] | volume = 79 | issue = 6 | pages = 1752–1760 | year = 2008 | month = November–December | doi = 10.1111/j.1467-8624.2008.01223.x | pmid = 19037947 }}</ref> when infants are exposed to faces, and it varies depending on factors including facial expression and eye gaze direction.<ref name="ReferenceA"/><ref name="Stefanie Hoehl & Tricia Striano 2008 1752–1760"/>
   
 
==Adult face perception==
 
==Adult face perception==
Theories about the processes involved in adult face perception have largely come from two sources; research on normal adult face perception and the study of impairments in face perception that are caused by [[brain injury]] or [[neurological illness]].
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Theories about the processes involved in adult face perception have largely come from two sources: research on normal adult face perception and the study of impairments in face perception that are caused by [[acquired brain injury|brain injury]] or [[neurological illness]]. Novel [[optical illusion]]s such as the [[Flashed Face Distortion Effect]], in which scientific [[phenomenology (science)|phenomenology]] outpaces neurological theory, also provide areas for research.
   
One of the most widely accepted theories of face perception<sup>[[Face perception#References|2]]</sup> argues that understanding faces involves several stages; from basic perceptual manipulations on the sensory information to derive details about the person (such as age, gender or attractiveness), to being able to recall meaningful details such as their name and any relevant past experiences of the individual.
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One of the most widely accepted theories of face perception argues that understanding faces involves several stages:<ref>{{Cite journal|author=Bruce V, Young A |title=Understanding face recognition |journal=Br J Psychology |volume=77 |issue=Pt 3 |pages=305–27 |year=1986 |month=August |pmid=3756376|doi=10.1111/j.2044-8295.1986.tb02199.x}}</ref> from basic perceptual manipulations on the sensory information to derive details about the person (such as age, gender or attractiveness), to being able to recall meaningful details such as their name and any relevant past experiences of the individual.
   
This model (developed by psychologists Vicki Bruce and Andrew Young) argues that face perception might involve several independent sub-processes working in unison.
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This model (developed by psychologists [[Vicki Bruce]] and Andrew Young) argues that face perception might involve several independent sub-processes working in unison.
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# A "view centered description" is derived from the perceptual input. Simple physical aspects of the face are used to work out age, gender or basic facial expressions. Most analysis at this stage is on feature-by-feature basis. That initial information is used to create a structural model of the face, which allows it to be compared to other faces in memory, and across views. This explains why the same person seen from a novel angle can still be recognized. This structural encoding can be seen to be specific for upright faces as demonstrated by the [[Thatcher effect]]. The structurally encoded representation is transferred to notional "face recognition units" that are used with "personal identity nodes" to identify a person through information from [[semantic memory]]. The natural ability to produce someone's name when presented with their face has been shown in experimental research to be damaged in some cases of brain injury, suggesting that naming may be a separate process from the memory of other information about a person.
   
# A 'view centred description' is derived from the perceptual input. Simple physical aspects of the face are used to work out age, gender or simple [[facial expression]]s. Most analysis at this stage is on feature-by-feature basis.
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The study of [[prosopagnosia]] (an impairment in recognizing faces which is usually caused by brain injury) has been particularly helpful in understanding how normal face perception might work. Individuals with prosopagnosia may differ in their abilities to understand faces, and it has been the investigation of these differences which has suggested that several stage theories might be correct.
# This initial information is used to create a structural model of the face, which allows it to be compared to other faces in memory, and across views. This explains why the same person seen from a novel angle can still be recognised. This structural encoding can be seen to be specific for upright faces as demonstrated by the [[Thatcher effect]].
 
# The structurally encoded representation is transferred to notional 'face recognition units' which in conjunction with 'person identity nodes' allow the person to be identified by information from [[semantic memory]]. Person identity nodes have also been conceptualized as a 'personality schema' that functions as an organization key for the retrieval of face-related semantic information<sup>8.</sup> Interestingly, the ability to produce someone's name when presented with their face has been shown to be selectively damaged in some cases of brain injury, suggesting that naming may be a separate process from being able to produce other information about a person.
 
   
The study of [[prosopagnosia]] (an impairment in recognising faces which is usually caused by brain injury) has been particularly helpful in understanding how normal face perception might work. Individuals with prosopagnosia may differ in their abilities to understand faces, and it has been the investigation of these differences which has suggested that several stage theories might be correct.
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Face perception is an ability that involves many areas of the brain; however, some areas have been shown to be particularly important. Brain imaging studies typically show a great deal of activity in an area of the [[temporal lobe]] known as the [[fusiform gyrus]], an area also known to cause prosopagnosia when damaged (particularly when damage occurs on both sides). This evidence has led to a particular interest in this area and it is sometimes referred to as the ''fusiform face area'' for that reason.<ref name="Kanwisher N, McDermott J, Chun MM 1997 4302–11">{{Cite journal|author=Kanwisher N, McDermott J, Chun MM |title =The fusiform face area: a module in human extrastriate cortex specialized for face perception |journal=J. Neurosci. |volume=17 |issue=11 |pages=4302–11 |date=1 June 1997 |pmid=9151747 |url= http://www.jneurosci.org/cgi/pmidlookup?view=long&pmid=9151747}}</ref>
   
Face perception is an ability which involves a great deal of the brain, however some areas have been shown to be particularly important. Brain imaging studies typically show a great deal of activity in an area of the [[temporal lobe]] known as the [[fusiform gyrus]], an area also known to cause prosopagnosia when damaged (particularly when damage occurs on both sides). This evidence has led to a particular interest in this area and it is sometimes referred to as the ''fusiform face area'' for that reason<sup>[[Face perception#References|3]]</sup>.
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===Neuroanatomy of facial processing===
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There are several parts of the brain that play a role in face perception. Rossion, Hanseeuw, and Dricot<ref>{{cite journal|last=Rossion|first=B.|coauthors=Hanseeuw, B., & Dricot, L.|title=Defining face perception areas in the human brain: A large scale factorial fMRI face localizer analysis.|journal=Brain and Cognition|year=2012|volume=79|issue=2|pages=138–157|doi=10.1016/j.bandc.2012.01.001}}</ref> used BOLD [[fMRI]] mapping to identify activation in the brain when subjects viewed both cars and faces. The majority of BOLD [[fMRI]] studies use blood oxygen level dependent (BOLD) contrast to determine which areas of the brain are activated by various cognitive functions.<ref>{{cite journal|last=KannurpattiRypmaBiswal|first=S.S.B.|title=Prediction of task-related BOLD fMRI with amplitude signatures of resting-state fMRI|journal=Frontiers in Systems Neuroscience|year=2012|month=March|volume=6|pages=1–7|doi=10.3389/fnsys.2012.00007}}</ref> They found that the occipital face area, located in the [[occipital lobe]], the [[fusiform face area]], the [[superior temporal sulcus]], the [[amygdala]], and the anterior/inferior cortex of the [[temporal lobe]], all played roles in contrasting the faces from the cars, with the initial face perception beginning in the [[fusiform face area]] and occipital face areas. This entire region links to form a network that acts to distinguish faces. The processing of faces in the brain is known as a "sum of parts" perception.<ref name="Gold 2012 427–434">{{cite journal|last=Gold|first=J.M.|coauthors=Mundy, P.J., & Tjan, B.S.|title=The perception of a face is no more than the sum of its parts|journal=Psychological Science|year=2012|volume=23|issue=4|pages=427–434|doi=10.1177/0956797611427407}}</ref> However, the individual parts of the face must be processed first in order to put all of the pieces together. In early processing, the occipital face area contributes to face perception by recognizing the eyes, nose, and mouth as individual pieces.<ref>{{cite journal|last=Pitcher|first=D.|coauthors=Walsh, V., & Duchaine, B.|title=The role of the occipital face area in the cortical face perception network|journal=Experimental Brain Research|year=2011|volume=209|issue=4|pages=481–493|doi=10.1007/s00221-011-2579-1}}</ref> Furthermore, Arcurio, Gold, and James<ref>{{cite journal|last=Arcurio|first=L.R.|coauthors=Gold, J.M., & James, T.W.|title=The response of face-selective cortex with single face parts and part combinations|journal=Neuropsychologia|year=2012|volume=50|issue=10|pages=2454–2459|doi=10.1016/j.neuropsychologia.2012.06.016}}</ref> used BOLD [[fMRI]] mapping to determine the patterns of activation in the brain when parts of the face were presented in combination and when they were presented singly. The occipital face area is activated by the visual perception of single features of the face, for example, the nose and mouth, and preferred combination of two-eyes over other combinations. This research supports that the occipital face area recognizes the parts of the face at the early stages of recognition. On the contrary, the [[fusiform face area]] shows no preference for single features, because the [[fusiform face area]] is responsible for "holistic/configural" information,<ref>{{cite journal|last=Arcurio|first=L.R.|coauthors=Gold, J.M., & James, T.W.|title=The response of face-selective cortex with single face parts and part combinations|journal=Neuropsychologia|year=2012|volume=50|issue=10|pages=2458|doi=10.1016/j.neuropsychologia.2012.06.016}}</ref> meaning that it puts all of the processed pieces of the face together in later processing. This theory is supported by the work of Gold et al.<ref name="Gold 2012 427–434"/> who found that regardless of the orientation of a face, subjects were impacted by the configuration of the individual facial features. Subjects were also impacted by the coding of the relationships between those features. This shows that processing is done by a summation of the parts in the later stages of recognition.
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Facial perception has well identified, neuroanatomical correlates in the brain. During the perception of faces, major activations occur in the extrastriate areas bilaterally, particularly in the [[Fusiform face area|fusiform face area (FFA)]], the occipital face area (OFA), and the [[Superior temporal sulcus|superior temporal sulcus (fSTS)]].<ref name="Liu">Liu J, Harris A, Kanwisher N. (2010). Perception of face parts and face configurations: An fmri study. ''Journal of Cognitive Neuroscience''. (1), 203–211.</ref><ref name="Rossion">Rossion, B., Caldara, R., Seghier, M., Schuller, A-M., Lazeyras, F., Mayer, E., (2003). A network of occipito-temporal face-sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing. A Journal of Neurology, 126 11 2381-2395</ref>
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The [[Fusiform face area|FFA]] is located in the lateral fusiform gyrus. It is thought that this area is involved in holistic processing of faces and it is sensitive to the presence of facial parts as well as the configuration of these parts. The [[Fusiform face area|FFA]] is also necessary for successful face detection and identification. This is supported by [[fMRI]] activation and studies on prospagnosia, which involves lesions in the [[Fusiform face area|FFA]].<ref name="Liu"/><ref name="Rossion"/><ref name="McCarthy 1997"/>
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The OFA is located in the inferior occipital gyrus.<ref name="Rossion"/> Similar to the FFA, this area is also active during successful face detection and identification, a finding that is supported by fMRI activation.<ref name="Liu"/> The OFA is involved and necessary in the analysis of facial parts but not in the spacing or configuration of facial parts. This suggests that the OFA may be involved in a facial processing step that occurs prior to the FFA processing.<ref name="Liu"/>
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The [[Superior temporal sulcus|fSTS]] is involved in recognition of facial parts and is not sensitive to the configuration of these parts. It is also thought that this area is involved in gaze perception.<ref name="Campbell">Campbell, R., Heywood, C.A., Cowey, A., Regard, M., and Landis, T. (1990). Sensitivity to eye gaze in prosopagnosic patients and monkeys with superior temporal sulcus ablation. Neuropsychologia, 28(11), 1123-1142</ref> The [[Superior temporal sulcus|fSTS]] has demonstrated increased activation when attending to gaze direction.<ref name="Liu"/>
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Bilateral activation is generally shown in all of these specialized facial areas.<ref name= McCarthy>{{cite journal |volume=8 |issue=2 |pages=139–46 |year=1996 |pmid=9081548|author-separator=,|author2=O'Leary DS|author3=Arndt S|display-authors=3|last4=Cizadlo|first4=T|last5=Hurtig|first5=R|last6=Rezai|first6=K|last7=Watkins|first7=GL|last8=Ponto|first8=LB|last9=Hichwa|first9=RD}}</ref><ref>{{Cite journal|author=Haxby JV, Horwitz B, Ungerleider LG, Maisog JM, Pietrini P, Grady CL |title=The functional organization of human extrastriate cortex: a PET-rCBF study of selective attention to faces and locations |journal=J. Neurosci. |volume=14 |issue=11 Pt 1 |pages=6336–53 |date=1 November 1994 |pmid=7965040 |url=http://www.jneurosci.org/cgi/pmidlookup?view=long&pmid=7965040}}</ref><ref>{{Cite journal|author=Haxby JV, Ungerleider LG, Clark VP, Schouten JL, Hoffman EA, Martin A |title=The effect of face inversion on activity in human neural systems for face and object perception |journal=Neuron |volume=22 |issue=1 |pages=189–99 |year=1999 |month=January |pmid=10027301 |url=http://linkinghub.elsevier.com/retrieve/pii/S0896-6273(00)80690-X |doi=10.1016/S0896-6273(00)80690-X}}</ref><ref>{{Cite journal|author=Puce A, Allison T, Asgari M, Gore JC, McCarthy G |title=Differential sensitivity of human visual cortex to faces, letterstrings, and textures: a functional magnetic resonance imaging study |journal=J. Neurosci. |volume=16 |issue=16 |pages=5205–15 |date=15 August 1996 |pmid= 8756449 |url=http://www.jneurosci.org/cgi/pmidlookup?view=long&pmid=8756449}}</ref><ref>{{Cite journal|author=Puce A, Allison T, Gore JC, McCarthy G |title=Face-sensitive regions in human extrastriate cortex studied by functional MRI |journal=J. Neurophysiol. |volume=74 |issue=3 |pages=1192–9 |year=1995 |month=September |pmid=7500143 |url=http://jn.physiology.org/cgi/pmidlookup?view=long&pmid=7500143}}</ref><ref>{{Cite journal|author=Sergent J, Ohta S, MacDonald B |title=Functional neuroanatomy of face and object processing. A positron emission tomography study |journal=Brain |volume=115 |issue=Pt 1 |pages=15–36 |year =1992 |month=February |pmid=1559150 |url=http://brain.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=1559150 |doi=10.1093/brain/115.1.15}}</ref> However there are some studies that include increased activation in one side over the other. For instance McCarthy (1997) has shown that the right fusiform gyrus is more important for facial processing in complex situations.<ref name="McCarthy 1997">McCarthy, G., Puce, A.,
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Gore, J., Allison, T., (1997). Face-Specific Processing in the Human Fusiform Gyrus. Journal of Cognitive Neuroscience, 9 5 605-610</ref>
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Gorno-Tempini and Price have shown that the fusiform gyri are preferentially responsive to faces, whereas the parahippocampal/lingual gyri are responsive to buildings.<ref>{{Cite journal|author=Gorno-Tempini ML, Price CJ |title=Identification of famous faces and buildings: a functional neuroimaging study of semantically unique items |journal=Brain |volume=124 |issue=Pt 10 |pages=2087–97 |year=2001 |month=October |pmid=11571224 |url=http://brain.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=11571224 |doi=10.1093/brain/124.10.2087}}</ref>
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It is important to note that while certain areas respond selectively to faces, facial processing involves many neural networks. These networks include visual and emotional processing systems as well. Emotional face processing research has demonstrated that there are some of the other functions at work. While looking at faces displaying emotions (especially those with fear facial expressions) compared to neutral faces there is increased activity in the right fusiform gyrus. This increased activity also correlates with increased amygdala activity in the same situations.<ref name="Vuilleumier">Vuilleumier P, Pourtois G, Distributed and interactive brain mechanisms during emotion face perception: Evidence from functional neuroimaging. Neuropsychologia 45 (2007) 174–194</ref> The emotional processing effects observed in the fusiform gyrus are decreased in patients with amygdala lesions.<ref name="Vuilleumier"/> This demonstrates possible connections between the amygdala and facial processing areas.<ref name="Vuilleumier"/>
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Another aspect that affects both the fusiform gyrus and the amygdala activation is the familiarity of faces. Having multiple regions that can be activated by similar face components indicates that facial processing is a complex process.<ref name="Vuilleumier"/>
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Ishai and colleagues have proposed the object form topology hypothesis, which posits that there is a topological organization of neural substrates for object and facial processing.<ref>{{Cite journal|author=Ishai A, Ungerleider LG, Martin A, Schouten JL, Haxby JV |title=Distributed representation of objects in the human ventral visual pathway |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=96 |issue=16 |pages=9379–84 |year=1999 |month=August |pmid=10430951 |pmc=17791 |url=http://www.pnas.org/cgi/pmidlookup?view=long&pmid=10430951 |doi=10.1073/pnas.96.16.9379}}</ref> However, Gauthier disagrees and suggests that the category-specific and process-map models could accommodate most other proposed models for the neural underpinnings of facial processing.<ref>{{Cite journal|author=Gauthier I |title=What constrains the organization of the ventral temporal cortex? |journal=Trends Cogn. Sci. (Regul. Ed.) |volume=4 |issue=1 |pages=1–2 |year=2000 |month=January |pmid=10637614 |url= http://linkinghub.elsevier.com/retrieve/pii/S1364-6613(99)01416-3 |doi=10.1016/S1364-6613(99)01416-3}}</ref>
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Most neuroanatomical substrates for facial processing are perfused by the middle cerebral artery (MCA). Therefore, facial processing has been studied using measurements of mean cerebral blood flow velocity in the middle cerebral arteries bilaterally. During facial recognition tasks, greater changes in the right middle cerebral artery (RMCA) than the left (LMCA) have been observed.<ref>{{Cite journal|author=Droste DW, Harders AG, Rastogi E |title=A transcranial Doppler study of blood flow velocity in the middle cerebral arteries performed at rest and during mental activities |journal=Stroke |volume=20 |issue=8 |pages=1005–11 |year=1989 |month=August |pmid=2667197 |url=http://stroke.ahajournals.org/cgi/pmidlookup?view=long&pmid=2667197|doi=10.1161/01.STR.20.8.1005}}</ref><ref>{{Cite journal|author=Harders AG, Laborde G, Droste DW, Rastogi E |title=Brain activity and blood flow velocity changes: a transcranial Doppler study |journal =Int. J. Neurosci. |volume=47 |issue=1–2 |pages=91–102 |year=1989 |month=July |pmid=2676884 |doi=10.3109/00207458908987421}}</ref> It has been demonstrated that men were right lateralized and women left lateralized during facial processing tasks.<ref>{{Cite journal|author=Njemanze PC |title=Asymmetry in cerebral blood flow velocity with processing of facial images during head-down rest |journal=Aviat Space Environ Med |volume=75 |issue=9 |pages=800–5 |year=2004 |month=September |pmid=15460633}}</ref>
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Just as memory and cognitive function separate the abilities of children and adults to recognize faces, the familiarity of a face may also play a role in the perception of faces.<ref name="Gold 2012 427–434"/> Zheng, Mondloch, and Segalowitz recorded [[event-related potentials]] in the brain to determine the timing of recognition of faces in the brain.<ref name="Zheng 2012 1451–1461">{{cite journal|last=Zheng|first=X.|coauthors=Mondloch, C.J. & Segalowitz, S.J.|title=The timing of individual face recognition in the brain|journal=Neuropsychologia|year=2012|volume=50|issue=7|pages=1451–1461|doi=10.1016/j.neuropsychologia.2012.02.030}}</ref> The results of the study showed that familiar faces are indicated and recognized by a stronger N250,<ref name="Zheng 2012 1451–1461"/> a specific wavelength response that plays a role in the visual memory of faces.<ref>{{cite journal|last=Eimer|first=M.|coauthors=Gosling, A., & Duchaine, B.|title=Electrophysiological markers of covert face recognition in developmental prosopagnosia|journal=Brain: A Journal of Neurology|year=2012|volume=135|issue=2|pages=542–554|doi=10.1093/brain/awr347}}</ref> Similarly, Moulson et al.<ref>{{cite journal|last=Moulson|first=M.C.|coauthors=Balas, B., Nelson, C., & Sinha, P.|title=EEG correlates of categorical and graded face perception.|journal=Neuropsychologia|year=2011|volume=49|issue=14|pages=3847–3853|doi=10.1016/j.neuropsychologia.2011.09.046}}</ref> found that all faces elicit the [[N170]] response in the brain.
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===Hemispheric asymmetries in facial processing capability===
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The mechanisms underlying gender-related differences in facial processing have not been studied extensively.
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Studies using electrophysiological techniques have demonstrated gender-related differences during a face recognition memory (FRM) task and a facial affect identification task (FAIT). The male subjects used a right, while the female subjects used a left, hemisphere neural activation system in the processing of faces and facial affect.<ref>{{Cite journal|author=Everhart DE, Shucard JL, Quatrin T, Shucard DW |title=Sex-related differences in event-related potentials, face recognition, and facial affect processing in prepubertal children |journal=Neuropsychology |volume=15 |issue=3 |pages=329–41 |year=2001 |month=July |pmid=11499988 |url=http://content.apa.org/journals/neu/15/3/329 |doi=10.1037/0894-4105.15.3.329}}</ref> Moreover, in facial perception there was no association to estimated [[intelligence]], suggesting that face recognition performance in women is unrelated to several basic cognitive processes.<ref>{{Cite journal|author=Herlitz A, Yonker JE |title=Sex differences in episodic memory: the influence of intelligence |journal=J Clin Exp Neuropsychol |volume=24 |issue=1 |pages=107–14 |year=2002 |month=February |pmid=11935429 |doi=10.1076/jcen.24.1.107.970}}</ref> Gender-related differences<ref>{{Cite journal|author=Smith WM |title=Hemispheric and facial asymmetry: gender differences |journal=Laterality |volume=5 |issue=3 |pages= 251–8 |year=2000 |month=July |pmid=15513145 |doi=10.1080/135765000406094}}</ref> may suggest a role for [[sex hormones]]. In females there may be variability for psychological functions<ref>{{Cite journal|author= Voyer D, Voyer S, Bryden MP |title=Magnitude of sex differences in spatial abilities: a meta-analysis and consideration of critical variables |journal=Psychol Bull |volume=117 |issue=2 |pages=250–70 |year=1995 |month=March |pmid=7724690 |url=http://content.apa.org/journals/bul/117/2/250 |doi=10.1037/0033-2909.117.2.250}}</ref> related to differences in hormonal levels during different phases of the [[menstrual cycle]].<ref>{{Cite journal|author=Hausmann M |title=Hemispheric asymmetry in spatial attention across the menstrual cycle |journal=Neuropsychologia |volume=43 |issue=11 |pages=1559–67 |year=2005 |pmid=16009238 |doi= 10.1016/j.neuropsychologia.2005.01.017 |url=http://linkinghub.elsevier.com/retrieve/pii/S0028-3932(05)00096-5}}</ref>
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Data obtained in norm and in pathology support asymmetric face processing.<ref>{{Cite journal|author=De Renzi E |title=Prosopagnosia in two patients with CT scan evidence of damage confined to the right hemisphere |journal=Neuropsychologia |volume=24 |issue=3 |pages=385–9 |year=1986 |pmid= 3736820 |doi=10.1016/0028-3932(86)90023-0}}</ref><ref>{{Cite journal|author=De Renzi E, Perani D, Carlesimo GA, Silveri MC, Fazio F |title=Prosopagnosia can be associated with damage confined to the right hemisphere--an MRI and PET study and a review of the literature |journal=Neuropsychologia |volume=32 |issue=8 |pages=893–902 |year=1994 |month=August |pmid=7969865 |url=http://linkinghub.elsevier.com/retrieve/pii/0028-3932(94)90041-8 |doi=10.1016/0028-3932(94)90041-8}}</ref><ref>{{Cite journal|author=Mattson AJ, Levin HS, Grafman J |title=A case of prosopagnosia following moderate closed head injury with left hemisphere focal lesion |journal=Cortex |volume=36 |issue=1 |pages=125–37 |year=2000 |month=February |pmid=10728902 |doi=10.1016/S0010-9452(08)70841-4}}</ref> Gorno-Tempini and others in 2001, suggested that the left inferior frontal cortex and the bilateral occipitotemporal junction respond equally to all face conditions. Some neuroscientists contend that both the left inferior frontal cortex ([[Brodmann area 47]]) and the occipitotemporal junction are implicated in facial memory.<ref>{{Cite journal|author=Barton JJ, Cherkasova M |title=Face imagery and its relation to perception and covert recognition in prosopagnosia |journal=Neurology |volume=61 |issue=2 |pages=220–5 |year=2003 |month=July |pmid=12874402 |url=http://www.neurology.org/cgi/pmidlookup?view=long&pmid=12874402|doi=10.1212/01.WNL.0000071229.11658.F8}}</ref><ref>{{Cite journal|author= Sprengelmeyer R, Rausch M, Eysel UT, Przuntek H |title=Neural structures associated with recognition of facial expressions of basic emotions |journal=Proc. Biol. Sci. |volume=265 |issue=1409 |pages=1927–31 |year=1998 |month=October |pmid=9821359 |pmc=1689486 |doi=10.1098/rspb.1998.0522 |url=http://rspb.royalsocietypublishing.org/cgi/pmidlookup?view=long&pmid=9821359}}</ref><ref>{{Cite journal|author=Verstichel P |title=[Impaired recognition of faces: implicit recognition, feeling of familiarity, role of each hemisphere] |language=French |journal=Bull. Acad. Natl. Med. |volume=185 |issue=3 |pages=537–49; discussion 550–3 |year=2001 |pmid=11501262}}</ref> The right inferior temporal/fusiform gyrus responds selectively to faces but not to non-faces. The right temporal pole is activated during the discrimination of familiar faces and scenes from unfamiliar ones.<ref>{{Cite journal|author=Nakamura K |title=Functional delineation of the human occipito-temporal areas related to face and scene processing. A PET study |journal=Brain |volume=123 |issue=Pt 9 |pages=1903–12 |year=2000 |month=September |pmid=10960054 |url=http://brain.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=10960054 |doi=10.1093/brain/123.9.1903|author-separator=,|author2=Kawashima R|author3=Sato N|display-authors=3|last4=Nakamura|first4=A|last5=Sugiura|first5=M|last6=Kato|first6=T|last7=Hatano|first7=K|last8=Ito|first8=K|last9=Fukuda|first9=H}}</ref> Right asymmetry in the mid temporal lobe for faces has also been shown using 133-Xenon measured cerebral blood flow (CBF).<ref>{{Cite journal|author=Gur RC |title=Effects of memory processing on regional brain activation: cerebral blood flow in normal subjects |journal=Int. J. Neurosci. |volume=72 |issue=1–2 |pages=31–44 |year=1993 |month=September |pmid=8225798 |doi=10.3109/00207459308991621|author-separator=,|author2=Jaggi JL|author3=Ragland JD|display-authors=3|last4=Resnick|first4=Susan M.|last5=Shtasel|first5=Derri|last6=Muenz|first6=Larry|last7=Gur|first7=Raquel E.}}</ref> Other investigators have observed right lateralization for facial recognition in previous electrophysiological and imaging studies.<ref>{{Cite journal|author=Ojemann JG, Ojemann GA, Lettich E |title=Neuronal activity related to faces and matching in human right nondominant temporal cortex |journal=Brain |volume=115 |issue=Pt 1 |pages=1–13 |year=1992 |month=February |pmid= 1559147 |url=http://brain.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=1559147 |doi=10.1093/brain/115.1.1}}</ref>
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The implication of the observation of asymmetry for facial perception would be that different hemispheric strategies would be implemented. The right hemisphere would be expected to employ a holistic strategy, and the left an analytic strategy.<ref>{{Cite journal|author=Bogen JE |title=The other side of the brain. I. Dysgraphia and dyscopia following cerebral commissurotomy |journal=Bull Los Angeles Neurol Soc |volume=34 |issue=2 |pages=73–105 |year=1969 |month=April |pmid=5792283}}</ref><ref>{{Cite journal|author=Bogen JE |title=Some educational aspects of hemispheric specialization |journal=UCLA Educator |volume= 17 |pages=24–32 |year=1975}}</ref><ref>{{Cite journal|author=Bradshaw JL, Nettleton NC |title=The nature of hemispheric specialization in man |journal=Behavioral and Brain Science |volume=4 |pages=51–91 |year= 1981 |doi=10.1017/S0140525X00007548}}</ref><ref>{{Cite journal|author=Galin D |title=Implications for psychiatry of left and right cerebral specialization. A neurophysiological context for unconscious processes |journal=Arch. Gen. Psychiatry |volume=31 |issue=4 |pages=572–83 |year=1974 |month=October |pmid=4421063 |url=http://archpsyc.ama-assn.org/cgi/pmidlookup?view=long&pmid=4421063|doi=10.1001/archpsyc.1974.01760160110022}}</ref> In 2007, Philip Njemanze, using a novel functional transcranial Doppler (fTCD) technique called [[Transcranial doppler#Functional transcranial Doppler (fTCD)|functional transcranial Doppler spectroscopy]] (fTCDS), demonstrated that men were right lateralized for object and facial perception, while women were left lateralized for facial tasks but showed a right tendency or no lateralization for object perception.<ref>{{Cite journal|author=Njemanze PC |title=Cerebral lateralisation for facial processing: gender-related cognitive styles determined using Fourier analysis of mean cerebral blood flow velocity in the middle cerebral arteries |journal=Laterality |volume=12 |issue=1 |pages=31–49 |year=2007 |month=January |pmid=17090448 |doi=10.1080/13576500600886796 |url=http://www.informaworld.com/openurl?genre=article&doi=10.1080/13576500600886796&magic=pubmed&#124;1B69BA326FFE69C3F0A8F227DF8201D0}}</ref> Njemanze demonstrated using fTCDS, summation of responses related to facial stimulus complexity, which could be presumed as evidence for topological organization of these cortical areas in men. It may suggest that the latter extends from the area implicated in object perception to a much greater area involved in facial perception.
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This agrees with the object form topology hypothesis proposed by Ishai and colleagues in 1999. However, the relatedness of object and facial perception was process based, and appears to be associated with their common holistic processing strategy in the right hemisphere. Moreover, when the same men were presented with facial paradigm requiring analytic processing, the left hemisphere was activated. This agrees with the suggestion made by Gauthier in 2000, that the extrastriate cortex contains areas that are best suited for different computations, and described as the process-map model. Therefore, the proposed models are not mutually exclusive, and this underscores the fact that facial processing does not impose any new constraints on the brain other than those used for other stimuli.
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It may be suggested that each stimulus was mapped by category into face or non-face, and by process into holistic or analytic. Therefore, a unified category-specific process-mapping system was implemented for either right or left cognitive styles. Njemanze in 2007, concluded that, for facial perception, men used a category-specific process-mapping system for right cognitive style, but women used same for the left.
   
 
===Controversies===
 
===Controversies===
Whilst a great deal of resources seem to be used by the mind and brain to understand the face, opinion is divided whether we genuinely develop specific skills for understanding faces, or whether face perception is just part of a general skill for making within-category discriminations, such as recognising and differentiating between similar animals or plants. Recognising a face involves a process of [[analogy]].
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{{criticism section|date=September 2011}}
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[[File:Martian face viking cropped.jpg|thumb|right|Many people see a "face" in this satellite image of the [[Cydonia (region of Mars)|Cydonia]] region on [[Mars]], due to the human ability to perceive faces even in inanimate objects, a phenomenon known as ''[[pareidolia]]''.]]
   
Proponents of this view argue that the differences seen between faces and non-face objects in experimental studies are due to faces being particularly difficult to distinguish and observers having acquired expertise at making these discriminations. Although we often assume that faces are relatively unique, statistically they are quite similar, so a great deal of [[cognition|cognitive]] effort is needed to differentiate them. According to this view, faces are nothing more than a particularly difficult class of perceptual object which we have learned to distinguish at the expert level, much as we would learn to distinguish between other similar objects if much of our communication and survival depended on it.
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Cognitive neuroscientists [[Isabel Gauthier]] and [[Michael Tarr]] are two of the major proponents of the view that face recognition involves expert discrimination of similar objects (See the [http://www.psy.vanderbilt.edu/faculty/gauthier/PEN/ Perceptual Expertise Network]). Other scientists, in particular [[Nancy Kanwisher]] and her colleagues, argue that face recognition involves processes that are face-specific and that are not recruited by expert discriminations in other object classes (see the [http://web.mit.edu/bcs/nklab/expertise.shtml domain specificity]).
   
Cognitive Neuroscientists [[Isabel Gauthier]] and [[Michael Tarr]] are two of the major proponents of the view that face recognition involves expert discrimination of similar objects (See the [http://www.psy.vanderbilt.edu/faculty/gauthier/PEN/ Perceptual Expertise Network]). Other scientists, in particular [[Nancy Kanwisher]] and her colleagues, argue that face recognition involves processes that are face-specific and that are not recruited by expert discriminations in other object classes (See the [http://web.mit.edu/bcs/nklab/expertise.shtml domain specificity]).
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Studies by Gauthier have shown that an area of the brain known as the [[fusiform gyrus]] (sometimes called the "fusiform face area, (FFA)" because it is active during face recognition) is also active when study participants are asked to discriminate between different types of birds and cars,<ref>{{Cite journal|author=Gauthier I, Skudlarski P, Gore JC, Anderson AW |title=Expertise for cars and birds recruits brain areas involved in face recognition |journal=Nat. Neurosci. |volume=3 |issue=2 |pages=191–7 |year=2000 |month=February |pmid=10649576 |doi=10.1038/72140}}</ref> and even when participants become expert at distinguishing computer generated nonsense shapes known as [[greeble (psychology)|greebles]].<ref>{{Cite journal|author=Gauthier I, Tarr MJ, Anderson AW, Skudlarski P, Gore JC |title=Activation of the middle fusiform 'face area' increases with expertise in recognizing novel objects |journal=Nat. Neurosci. |volume=2 |issue=6 |pages=568–73 |year=1999 |month=June |pmid=10448223 |doi= 10.1038/9224}}</ref> This suggests that the fusiform gyrus may have a general role in the recognition of similar visual objects. Yaoda Xu, then a post doctoral fellow with Nancy Kanwisher, replicated the car and bird expertise study using an improved fMRI design that was less susceptible to attentional accounts.
   
Studies by Gauthier have shown that an area of the brain known as the [[fusiform gyrus]] (sometimes called the 'fusiform face area' because it is active during face recognition) is also active when study participants are asked to discriminate between different types of birds and cars<sup>[[Face perception#References|4]]</sup> and even when participants become expert at distinguishing computer generated nonsense shapes known as Greebles<sup>[[Face perception#References|5]]</sup>. This suggests that the fusiform gyrus may have a general role in the recognition of similar visual objects.
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The activity found by Gauthier when participants viewed non-face objects was not as strong as when participants were viewing faces, however this could be because we have much more expertise for faces than for most other objects. Furthermore, not all findings of this research have been successfully replicated, for example, other research groups using different study designs have found that the fusiform gyrus is specific to faces and other nearby regions deal with non-face objects.<ref>{{Cite journal|author=Grill-Spector K, Knouf N, Kanwisher N |title=The fusiform face area subserves face perception, not generic within-category identification |journal=Nat. Neurosci. |volume=7 |issue=5 |pages=555–62 |year=2004 |month=May |pmid=15077112 |doi=10.1038/nn1224}}</ref>
   
However, the activity found by Gauthier when participants viewed non-face objects was not as strong as when participants were viewing faces. Furthermore, not all of findings of this research have been successfully replicated, for example, other research groups using different study designs have found that the [[fusiform gyrus]] is specific to faces and other nearby regions deal with non-face objects<sup>[[Face perception#References|6]]</sup>. However, these failures to replicate are often based upon different designs and often fail to use objects from the specific domain of expertises for the expert subjects. Gauthier and colleagues have argued that one study that failed to find an expertise effect used "mostly antique cars", however in fact the target stimuli in this study were jeeps, and only some of the distractors were antique cars (because of their smilarity in shape to jeeps). More to the point, failures to replicate are null effects and can occur for many different reasons. In contrast, each replication adds a great deal of weight to a particular argument. With regard to "face specific" effects in neuroimaging, there are now multiple replications with Greebles, with birds and cars<sup>[[Face perception#References|7]]</sup>, and a new study with chess experts.
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However, these failures to replicate are difficult to interpret, because studies vary on too many aspects of the method. It has been argued that some studies test experts with objects that are slightly outside of their domain of expertise. More to the point, failures to replicate are null effects and can occur for many different reasons. In contrast, each replication adds a great deal of weight to a particular argument. With regard to "face specific" effects in neuroimaging, there are now multiple replications with Greebles, with birds and cars,<ref>{{Cite journal|author=Xu Y |title=Revisiting the role of the fusiform face area in visual expertise |journal=Cereb. Cortex |volume=15 |issue=8 |pages=1234–42 |year=2005 |month=August |pmid=15677350 |doi=10.1093/cercor/bhi006 |url=http://cercor.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=15677350}}</ref> and two unpublished studies with chess experts.<ref>{{Cite journal|author=Righi G, Tarr MJ |title=Are chess experts any different from face, bird, or greeble experts? |journal=Journal of Vision |volume=4 |issue=8 |pages=504–504 |year=2004 |url=http://journalofvision.org/4/8/504/ |doi=10.1167/4.8.504}}</ref><ref>[http://www.youtube.com/watch?v=WLQbTd6RFhY] My Brilliant Brain, partly about grandmaster Susan Polgar, shows brain scans of the fusiform gyrus while Polgar viewed chess diagrams.</ref>
   
Therefore, it is still not clear in exactly which situations the [[fusiform gyrus]] becomes active, although it is certain that face recognition relies heavily on this area and damage to it can lead to severe [[prosopagnosia|face recognition impairment]].
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Although it is sometimes found that expertise recruits the FFA (e.g. as hypothesized by a proponent of this view in the preceding paragraph), a more common and less controversial finding is that expertise leads to focal category-selectivity in the fusiform gyrus—a pattern similar in terms of antecedent factors and neural specificity to that seen for faces. As such, it remains an open question as to whether face recognition and expert-level object recognition recruit similar neural mechanisms across different subregions of the fusiform or whether the two domains literally share the same neural substrates. Moreover, at least one study argues that the issue as to whether expertise-predicated category-selective areas overlap with the FFA is nonsensical in that multiple measurements of the FFA within an individual person often overlap no more with each other than do measurements of FFA and expertise-predicated regions.<ref>{{Cite journal|author=Kung CC, Peissig JJ, Tarr MJ |title=Is region-of-interest overlap comparison a reliable measure of category specificity? |journal=J Cogn Neurosci |volume=19 |issue=12 |pages=2019–34 |year=2007 |month=December |pmid=17892386 |doi=10.1162/jocn.2007.19.12.2019 |url=http://www.mitpressjournals.org/doi/abs/10.1162/jocn.2007.19.12.2019?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dncbi.nlm.nih.gov}}</ref> At the same time, numerous studies have failed to replicate them altogether.{{Citation needed|date=September 2008}} For example, four published fMRI studies have asked whether expertise has any specific connection to the FFA in particular, by testing for expertise effects in both the FFA and a nearby but not face-selective region called LOC (Rhodes et al., JOCN 2004; Op de Beeck et al., JN 2006; Moore et al., JN 2006; Yue et al. VR 2006). In all four studies, expertise effects are significantly stronger in the LOC than in the FFA, and indeed expertise effects were only borderline significant in the FFA in two of the studies, while the effects were robust and significant in the LOC in all four studies.{{Citation needed|date=December 2010}}
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Therefore, it is still not clear in exactly which situations the fusiform gyrus becomes active, although it is certain that face recognition relies heavily on this area and damage to it can lead to severe [[prosopagnosia|face recognition impairment]].
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==Ethnicity==
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{{main|cross-race effect}}
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Differences in own- versus other-race face recognition and perceptual discrimination was first researched in 1914<ref name="Feingold">{{cite journal | author = Feingold CA | year = 1914 | title = The influence of environment on identification of persons and things | url = | journal = Journal of Criminal Law and Police Science | volume = 5 | issue = | pages = 39–51 }}</ref> Humans tend to perceive people of other races than their own to all look alike:
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<blockquote>Other things being equal, individuals of a given race are distinguishable from each other in proportion to our familiarity, to our contact with the race as whole. Thus, to the uninitiated American all Asiatics look alike, while to the Asiatics, all White men look alike.<ref name="Feingold"/></blockquote>
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This phenomenon is known as the [[cross-race effect]], own-race effect, other-race effect, own race bias or interracial-face-recognition-deficit.<ref>{{Cite journal|author=Walker PM, Tanaka JW |title=An encoding advantage for own-race versus other-race faces |journal=Perception |volume=32 |issue=9 |pages=1117–25 |year=2003 |pmid=14651324 |doi=10.1068/p5098}}</ref> The effect occurs as early as 170ms in the brain with the [[N170]] brain response to faces.<ref>{{cite journal | author = Vizioli L, Rousselet GA, Caldara R | year = 2010 | title = Neural repetition suppression to identity is abolished by other-race faces | url = http://www.pnas.org/content/107/46/20081.full.pdf | journal = Proc Natl Acad Sci U S A | volume = 107 | issue = 46| pages = 20081–20086 | doi = 10.1073/pnas.1005751107 | pmc = 2993371 | pmid = 21041643 }}</ref>{{clarify|date=December 2010}}
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A meta-analysis, Mullen{{Citation needed|date=July 2008}} has found evidence that the other-race effect is larger among White subjects than among African American subjects, whereas Brigham and Williamson (1979, cited in Shepherd, 1981) obtained the opposite pattern. Shepherd also reviewed studies that found a main effect for race efface like that of the present{{Clarify|date=September 2008}} study, with better performance on White faces,<ref>Malpass & Kravitz, 1969; Cross, Cross, & Daly, 1971; Shepherd, Deregowski, & Ellis, 1974; all cited in Shepherd, 1981</ref> other studies in which no difference was found,<ref>Chance, Goldstein, & McBride, 1975; Feinman & Entwistle, 1976; cited in Shepherd, 1981</ref> and yet other studies in which performance was better on African American faces.<ref>Brigham & Karkowitz, 1978; Brigham & Williamson, 1979; cited in Shepherd, 1981</ref> Overall, Shepherd reports a reliable positive correlation between the size of the effect of target race (indexed by the difference in proportion correct on same- and other-race faces) and self-ratings of amount of interaction with members of the other race, r(30) = .57, p < .01. This correlation is at least partly an artifact of the fact that African American subjects, who performed equally well on faces of both races, almost always responded with the highest possible self-rating of amount of interaction with white people (M = 4.75), whereas their white counterparts both demonstrated an other-race effect and reported less other-race interaction (M = 2.13); the difference in ratings was reliable, £(30) = 7.86, p < .01<ref name="otherrace">[http://web.uvic.ca/~slindsay/publications/1991LindJackChristian.pdf Other-Race Face Perception] D. Stephen Lindsay, Philip C. Jack, Jr., and Marcus A. Christian. Williams College</ref>
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Further research points to the importance of other-race experience in own- versus other-race face processing (O'Toole et al., 1991; Slone et al., 2000; Walker & Tanaka, 2003). In a series of studies, Walker and colleagues showed the relationship between amount and type of other-race contact and the ability to perceptually differentiate other-race faces (Walker & Tanaka, 2003; Walker & [[Miles Hewstone|Hewstone]], 2006a,b; 2007). Participants with greater other-race experience were consistently more accurate at discriminating between other-race faces than were participants with less other-race experience.
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In addition to other-race contact, there is suggestion that the own-race effect is linked to increased ability to extract information about the spatial relationships between different features.<ref>Diamond & Carey, 1986; Rhodeset al.,1989</ref> Richard Ferraro writes that facial recognition is an example of a neuropsychological measure that can be used to assess cognitive abilities that are salient within African-American culture.<ref>{{Cite book|author=F. Richard Ferraro |title=Minority and Cross-cultural Aspects of Neuropsychological Assessment |series=Studies on Neuropsychology, Development and Cognition |volume=4 |publisher=Psychology Press |location=East Sussex |year=2002 |page=90 |isbn=90-265-1830-7}}</ref> Daniel T. Levin writes that the deficit occurs because people emphasize visual information specifying race at the expense of individuating information when recognizing faces of other races.<ref>{{Cite journal|author=Levin DT |title=Race as a visual feature: using visual search and perceptual discrimination tasks to understand face categories and the cross-race recognition deficit |journal=J Exp Psychol Gen |volume=129 |issue=4 |pages=559–74 |year=2000 |month=December |pmid=11142869 |url=http://content.apa.org/journals/xge/129/4/559 |doi=10.1037/0096-3445.129.4.559}}</ref> Further research using perceptual tasks could shed light on the specific cognitive processes involved in the other-race effect.<ref name="otherrace"/> The question if the own-race effect can be overcome was already indirectly answered by Ekman & Friesen in 1976 and Ducci, Arcuri, Georgis & Sineshaw in 1982. They had observed that people from New Guinea and Ethiopia who had had contact with white people before had a significantly better emotional recognition rate.
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Studies on adults have also shown sex differences in face recognition. Men tend to recognize fewer faces of women than women do, whereas there are no sex differences with regard to male faces.<ref>{{Cite journal|author=Rehnman J, Herlitz A |title=Higher face recognition ability in girls: Magnified by own-sex and own-ethnicity bias |journal=Memory |volume=14 |issue=3 |pages=289–96 |year=2006 |month=April |pmid= 16574585 |doi=10.1080/09658210500233581 |url=http://www.informaworld.com/openurl?genre=article&doi=10.1080/09658210500233581&magic=pubmed&#124;&#124;1B69BA326FFE69C3F0A8F227DF8201D0}}</ref>
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==In individuals with autism spectrum disorder==
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[[Autism spectrum disorder]] (ASD) is a comprehensive neural developmental disorder that produces many deficits including social, communicative,<ref name=tanakabook>{{cite book|last=Tanaka|first=J.W.|title=The development of face processing|year=2003|publisher=Hogrefe & Huber Publishers|location=Ohio|isbn=9780889372641|pages=101–119|coauthors=Lincoln, S.; Hegg, L.|editor=Schwarzer, G.; Leder, H.|chapter=A framework for the study and treatment of face processing deficits in autism}}</ref> and perceptual deficits.<ref name=Behrmann>{{cite journal|last=Behrmann|first=Marlene|coauthors=Avidan, Galia; Leonard, Grace L.; Kimchi, Rutie; Beatriz, Luna; Humphreys, Kate; Minshew, Nancy|title=Configural processing in autism and its relationship to face processing|journal=Neuropsychologia|year=2006|volume=44|pages=110–129|doi=10.1016/j.neuropsychologia.2005.04.002|accessdate=2/24/2013}}</ref> Of specific interest, individuals with autism exhibit difficulties in various aspects of facial perception, including facial identity recognition and recognition of emotional expressions.<ref name=Schreibman>{{cite book|last=Schreibman|first=Laura|title=Autism|year=1988|publisher=Sage Publications|location=Newbury Park|isbn=0803928092|pages=14–47}}</ref><ref name=Weigelt>{{cite journal|last=Weigelt|first=Sarah|coauthors=Koldewyn, Kami; Kanwisher, Nancy|title=Face identity recognition in autism spectrum disorders: A review of behavioral studies|journal=Neuroscience & Biobehavioral Reviews|year=2012|volume=36|pages=1060–1084|doi=10.1016/j.neubiorev.2011.12.008|accessdate=2/24/2013}}</ref> These deficits are suspected to be a product of abnormalities occurring in both the early and late stages of facial processing.<ref name=Dawson>{{cite journal|last=Dawson|first=Geraldine|coauthors=Webb, Sara Jane; McPartland, James|title=Understanding the nature of face processing impairment in autism: Insights from behavioral and electrophysiological studies|journal=Developmental Neuropsychology|year=2005|volume=27|pages=403–424|pmid=15843104}}</ref>
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===Speed and methods===
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People with ASD process face and non-face stimuli with the same speed.<ref name=Dawson /><ref name=Kita>{{cite journal|last=Kita|first=Yosuke|coauthors=Inagaki, Masumi|title=Face recognition in patients with Autism Spectrum Disorder|journal=Brain and Nerve|year=2012|volume=64|pages=821–831|pmid=22764354|accessdate=2/25/2013}}</ref> In typically developing individuals, there is a preference for face processing, thus resulting in a faster processing speed in comparison to non-face stimuli.<ref name=Dawson /><ref name=Kita /> These individuals primarily utilize [[global precedence|holistic processing]] when perceiving faces.<ref name=Behrmann /> Contrastingly, individuals with ASD employ part-based processing or [[top-down and bottom-up design|bottom-up processing]], focusing on individual features rather than the face as a whole.<ref name=Grelotti>{{cite journal|last=Grelotti|first=David|coauthors=Gauthier, Isabel; Schultz, Robert|title=Social interest and the development of cortical face specialization: What autism teaches us about face processing|url=http://www.psy.vanderbilt.edu/faculty/gauthier/publi/GrGaSc_inpress.pdf|journal=Developmental Psychobiology|year=2002|volume=40|pages=213–235|doi=10.1002/dev.10028|accessdate=2/24/2012}}</ref><ref name=Riby>{{cite journal|last=Riby|first=Deborah|coauthors=Doherty-Sneddon Gwyneth|title=The eyes or the mouth? Feature salience and unfamiliar face processing in Williams syndrome and autism|journal=The Quarterly Journal of Experimental Psychology|year=2009|volume=62|pages=189–203|doi=10.1080/17470210701855629|accessdate=2/24/2013}}</ref> When focusing on the individual parts of the face, persons with ASD direct their gaze primarily to the lower half of the face, specifically the mouth, varying from the eye trained gaze of typically developing people.<ref name=Grelotti /><ref name=Riby /><ref name=Joseph>{{cite journal|last=Joseph|first=Robert|coauthors=Tanaka, James|title=Holistic and part-based face recognition in children with autism|journal=Journal of Child Psychology and Psychiatry|year=2003|volume=44|pages=529–542|doi=10.1111/1469-7610.00142|accessdate=2/14/2012}}</ref><ref name=Langdell>{{cite journal|last=Langdell|first=Tim|title=Recognition of Faces: An approach to the study of autism|journal=Journal of Psychology and Psychiatry and Allied Disciplines (Blackwell)|year=1978|volume=19|pages=255–265|url=http://illiad.davidson.edu/pdf/162574.pdf|accessdate=2/12/2013}}</ref><ref name=Spezio>{{cite journal|last=Spezio|first=Michael|coauthors=Adolphs, Ralph; Hurley, Robert; Piven, Joseph|title=Abnormal use of facial information in high functioning autism|journal=Journal of Autism and Developmental Disorders|date=28 Sept 2006|volume=37|pages=929–939|doi=10.1007/s10803-006-0232-9|accessdate=2/13/2013}}</ref> This deviation from [[global precedence|holistic]] face processing does not employ the use of facial [[prototype theory|prototypes]], which are templates stored in memory that make for easy retrieval.<ref name=Weigelt /><ref name=textbook>{{cite book|last=Revlin|first=Russell|title=Cognition: Theory and Practice|year=2013|publisher=Worth Publishers|isbn=9780716756675|pages=98–101}}</ref>
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Additionally, individuals with ASD display difficulty with [[recognition memory]], specifically memory that aids in identifying faces. The memory deficit is selective for faces and does not extend to other objects or visual inputs.<ref name=Weigelt /> Some evidence lends support to the theory that these face-memory deficits are products of interference between connections of face processing regions.<ref name=Weigelt />
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===Associated difficulties===
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The atypical facial processing style of people with ASD often manifests in constrained social ability, due to decreased eye contact, [[joint attention]], interpretation of emotional expression, and communicative skills.<ref name=Triesch>{{cite journal|last=Triesch|first=Jochen|coauthors=Teuscher, Christof; Deak, Gedeon O.; Carlson, Eric|title=Gaze following: why (not) learn it?|journal=Developmental Science|year=2006|volume=9|pages=125–157|doi=10.1111/j.1467-7687.2006.00470.x|accessdate=2/24/2013}}</ref> These deficiencies can be seen in infants as young as 9 months; specifically in terms of poor eye contact and difficulties engaging in joint attention.<ref name=Dawson /> Some experts have even used the term 'face avoidance' to describe the phenomena where infants who are later diagnosed with ASD preferentially attend to non-face objects over faces.<ref name=tanakabook /> Furthermore, some have proposed that the demonstrated impairment in children with ASD's ability to grasp emotional content of faces is not a reflection of the incapacity to process emotional information, but rather, the result of a general inattentiveness to facial expression.<ref name=tanakabook /> The constraints of these processes that are essential to the development of communicative and social-cognitive abilities are viewed to be the cause of impaired social engagement and responsivity.<ref name=Volkmar>{{cite journal|last=Volkmar|first=Fred|coauthors=Chawarska, Kasia; Klin, Ami|title=Autism in infancy and early childhood|journal=Annual Reviews of Psychology|year=2005|volume=56|pages=315–316|doi=10.1146/annurev.psych.56.091103.070159|accessdate=2/24/2012}}</ref> Furthermore, research suggests that there exists a link between decreased face processing abilities in individuals with ASD and later deficits in [[Theory of Mind]]; for example, while typically developing individuals are able to relate others' emotional expressions to their actions, individuals with ASD do not demonstrate this skill to the same extent.<ref name=grosbois>{{cite book|last=Nader-Grosbois|first=N.|title=International handbook of autism and pervasive developmental disorders|year=2011|publisher=Springer Science & Business Media|location=New York|isbn=9781441980649|pages=127–157|coauthors=Day, J.M.|editor=Matson, J.L; Sturmey, R.|chapter=Emotional cognition: theory of mind and face recognition}}</ref>
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There is some contention about this causation however, resembling the [[chicken or the egg]] dispute. Others theorize that social impairment leads to perceptual problems rather than vice versa.<ref name=Grelotti /> In this perspective, a biological lack of social interest inherent to ASD inhibits developments of facial recognition and perception processes due to underutilization.<ref name=Grelotti /> Continued research is necessary to determine which theory is best supported.
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===Neurology ===
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Many of the obstacles that individuals with ASD face in terms of facial processing may be derived from abnormalities in the fusiform face area and amygdala, which have been shown to be important in face perception as discussed [[Face_perception#Neuroanatomy_of_facial_processing|above]]. Typically, the fusiform face area in individuals with ASD has reduced volume compared to normally developed persons.<ref name= Pierce>{{cite journal|last=Pierce|first=Karen|coauthors=Muller, R.A., Ambrose, J., Allen, G.,Chourchesne|title=Face processing occurs outside the fusiform 'face area' in autism: evidence from functional MRI|url = http://brain.oxfordjournals.org/content/124/10/2059.full.pdf+html|journal=Brain|year=2001|volume=124|pages=2059–2073|accessdate=2/13/2013}}</ref> This volume reduction has been attributed to deviant amygdala activity that does not flag faces as emotionally salient and thus decreases activation levels of the fusiform face area. This hypoactivity in the in the fusiform face area has been found in several studies.<ref name=Grelotti />
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Studies are not conclusive as to which brain areas people with ASD use instead. One study found that, when looking at faces, people with ASD exhibit activity in brain regions normally active when typically developing individuals perceive objects.<ref name=Grelotti /> Another study found that during facial perception, people with ASD use different neural systems, with each one of them using their own unique neural circuitry.<ref name=Pierce />
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===Compensation mechanisms===
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As ASD individuals age, scores on behavioral tests assessing ability to perform face-emotion recognition increase to levels similar to controls.<ref name=Dawson /><ref name=Harms /> Yet, it is apparent that the recognition mechanisms of these individuals are still atypical, though often effective.<ref name=Harms>{{cite journal|last=Harms|first=Madeline|coauthors=Martin, Alex; Wallace, Gregory|title=Facial emotion recognition in autism spectrum disorders: A review of behavioral and neuroimaging studies|journal=Neuropsychology Review|year=2010|volume=20|pages=290–322|doi=10.1007/s11065-010-9138-6|accessdate=2/24/2013}}</ref> In terms of face identity-recognition, compensation can take many forms including a more pattern-based strategy which was first seen in [[Global_precedence#Face_inversion|face inversion]] tasks.<ref name=Langdell /> Alternatively, evidence suggests that older individuals compensate by using mimicry of other’s facial expressions and rely on their motor feedback of facial muscles for face emotion-recognition.<ref name=Wright>{{cite journal|last=Wright|first=Barry|coauthors=Clarke, Natalie; Jordan, Jo; Young, Andrew; Clarke, Paula; Miles, Jermey; Nation, Kate; Clarke, Leesa; Williams, Christine|title=Emotion recognition in faces and the use of visual context Vo in young people with high-functioning autism spectrum disorders|journal=Autism|year=2008|volume=12|page=607-|doi=10.1177/1362361308097118|accessdate=2/24/2013}}</ref> These strategies help overcome the obstacles individuals with ASD face in interacting within social contexts.
   
 
==Artificial face perception==
 
==Artificial face perception==
A great deal of effort has been put into developing software that can recognise human faces; see [[facial recognition system]]. Much of the work has been done by a branch of [[artificial intelligence]] known as [[computer vision]] which uses findings from the psychology of face perception to inform software design.
+
A great deal of effort has been put into developing [[facial recognition system|software that can recognize human faces]]. Much of the work has been done by a branch of [[artificial intelligence]] known as [[computer vision]] which uses findings from the psychology of face perception to inform software design. Recent breakthroughs using noninvasive functional [[transcranial Doppler]] spectroscopy as demonstrated by Njemanze, 2007, to locate specific responses to facial stimuli have led to improved systems for facial recognition. The new system uses input responses called cortical long-term potentiation (CLTP) derived from Fourier analysis of mean blood flow velocity to trigger target face search from a computerized face database system.<ref>Njemanze, P.C. Transcranial doppler spectroscopy for assessment of brain cognitive functions. United States Patent Application No. 20040158155, August 12th, 2004</ref><ref>Njemanze, P.C. Noninvasive transcranial doppler ultrasound face and object recognition testing system. United States Patent No. 6,773,400, August 10th, 2004</ref> Such a system provides for brain-machine interface for facial recognition, and the method has been referred to as cognitive [[biometrics]].
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Another interesting application is the estimation of human age from face images. As an important hint for human communication, facial images contain lots of useful information including gender, expression, age, etc. Unfortunately, compared with other cognition problems, age estimation from facial images is still very challenging. This is mainly because the aging process is influenced not only by a person's genes but also many external factors. Physical condition, living style etc. may accelerate or slow the aging process. Besides, since the aging process is slow and with long duration, collecting sufficient data for training is fairly demanding work.<ref>{{Cite journal|url=http://pages.cs.wisc.edu/~huangyz/caip09_Long.pdf |title=Human age estimation by metric learning for regression problems |author=YangJing Long |journal=Proc. International Conference on Computer Analysis of Images and Patterns |year=2009 |pages=74–82}}</ref>
   
 
==See also==
 
==See also==
 
* [[Capgras delusion]]
 
* [[Capgras delusion]]
 
* [[Cognitive neuropsychology]]
 
* [[Cognitive neuropsychology]]
  +
* [[Cross-race effect]]
 
* [[Delusional misidentification syndrome]]
 
* [[Delusional misidentification syndrome]]
 
* [[Eigenface]]
 
* [[Eigenface]]
 
* [[Facial expressions]]
 
* [[Facial expressions]]
 
* [[Facial features]]
 
* [[Facial features]]
  +
* [[Fregoli syndrome]]
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* [[N170]], an [[event-related potential]] associated with viewing faces
 
* [[Prosopagnosia]]
 
* [[Prosopagnosia]]
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* [[Recognition of human individuals]]
 
* [[Social cognition]]
 
* [[Social cognition]]
 
* [[Social perception]]
 
* [[Social perception]]
 
* [[Thatcher effect]]
 
* [[Thatcher effect]]
* [[Recognition of human individuals]]
 
   
 
==References & Bibliography==
 
==References & Bibliography==

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Faceex
Although this picture merely consists of some vague blobs, the human brain seems to be "hardwired" to find a human face in the image.
LifeartistAdded by Lifeartist

Face perception is the process by which the brain and mind understand and interpret the face, particularly the human face.

The face is an important site for the identification of others and conveys significant social information. Probably because of the importance of its role in social interaction, psychological processes involved in face perception are known to be present from birth, complex, involve large and widely distributed areas in the brain and can be selectively damaged to cause a specific impairment in understanding faces known as prosopagnosia.

Development

From birth, infants possess rudimentary facial processing capacities. Infants as young as two days of age are capable of mimicking the facial expressions of an adult, displaying their capacity to note details like mouth and eye shape as well as to move their own muscles in a way that produces similar patterns in their faces.[1] However, despite this ability, newborns are not yet aware of the emotional content encoded within facial expressions. Five-month olds, when presented with an image of a person making a fearful expression and a person making a happy expression, pay the same amount of attention to and exhibit similar event-related potentials for both. When seven-month-olds are given the same treatment, they focus more on the fearful face, and their event-related potential for the scared face shows a stronger initial negative central component than the happy face. This result indicates an increased attentional and cognitive focus toward fear that reflects the threat-salient nature of the emotion.[2] In addition, infants’ negative central components were not different for new faces that varied in the intensity of an emotional expression but portrayed the same emotion as a face they had been habituated to but were stronger for different-emotion faces, showing that seven-month-olds regarded happy and sad faces as distinct emotive categories.[3]

The recognition of faces is an important neurological mechanism that an individual uses every day. Jeffrey and Rhodes[4] said that faces "convey a wealth of information that we use to guide our social interactions."[5] For example, emotions play a large role in our social interactions. The perception of a positive or negative emotion on a face affects the way that an individual perceives and processes that face. A face that is perceived to have a negative emotion is processed in a less holistic manner than a face displaying a positive emotion.[6] The ability of face recognition is apparent even in early childhood. By age five, the neurological mechanisms responsible for face recognition are present. Research shows that the way children process faces is similar to that of adults, however adults process faces more efficiently. The reason for this may be because of improvements in memory and cognitive functioning that occur with age.[7]

Infants are able to comprehend facial expressions as social cues representing the feelings of other people before they have been alive for a year. At seven months, the object of an observed face’s apparent emotional reaction is relevant in processing the face. Infants at this age show greater negative central components to angry faces that are looking directly at them than elsewhere, although the direction of fearful faces’ gaze produces no difference. In addition, two ERP components in the posterior part of the brain are differently aroused by the two negative expressions tested. These results indicate that infants at this age can at least partially understand the higher level of threat from anger directed at them as compared to anger directed elsewhere.[8] At least seven months of age, infants are also able to use others’ facial expressions to understand their behavior. Seven-month olds will look to facial cues to understand the motives of other people in ambiguous situations, as shown by a study in which they watched an experimenter’s face longer if she took a toy from them and maintained a neutral expression than if she made a happy expression.[9] Interest in the social world is increased by interaction with the physical environment. Training three-month-old infants to reach for objects with Velcro-covered “sticky mitts” increases the amount of attention that they pay to faces as compared to passively moving objects through their hands and non-trained control groups.[10]

In following with the notion that seven-month-olds have categorical understandings of emotion, they are also capable of associating emotional prosodies with corresponding facial expressions. When presented with a happy or angry face, shortly followed by an emotionally-neutral word read in a happy or angry tone, their ERPs follow different patterns. Happy faces followed by angry vocal tones produce more changes than the other incongruous pairing, while there was no such difference between happy and angry congruous pairings, with the greater reaction implying that infants held greater expectations of a happy vocal tone after seeing a happy face than an angry tone following an angry face. Considering an infant’s relative immobility and thus their decreased capacity to elicit negative reactions from their parents, this result implies that experience has a role in building comprehension of facial expressions.[11]

Several other studies indicate that early perceptual experience is crucial to the development of capacities characteristic of adult visual perception, including the ability to identify familiar others and to recognize and comprehend facial expressions.[12] The capacity to discern between faces, much like language, appears to have a broad potential in early life that is whittled down to kinds of faces that are experienced in early life.[12] Infants can discern between macaque faces at six months of age, but, without continued exposure, cannot at nine months of age. Being shown photographs of macaques during this three-month period gave nine-month-olds the ability to reliably tell between unfamiliar macaque faces.[13]

The neural substrates of face perception in infants are likely similar to those of adults, but the limits of imaging technology that are feasible for use with infants currently prevent very specific localization of function as well as specific information from subcortical areas[14] like the amygdala, which is active in the perception of facial expression in adults.[12] In a study on healthy adults, it was shown that faces are likely to be processed, in part, via a retinotectal (subcortical) pathway.[15]

However, there is activity near the fusiform gyrus,[14] as well as in occipital areas.[8] when infants are exposed to faces, and it varies depending on factors including facial expression and eye gaze direction.[3][8]

Adult face perception

Theories about the processes involved in adult face perception have largely come from two sources: research on normal adult face perception and the study of impairments in face perception that are caused by brain injury or neurological illness. Novel optical illusions such as the Flashed Face Distortion Effect, in which scientific phenomenology outpaces neurological theory, also provide areas for research.

One of the most widely accepted theories of face perception argues that understanding faces involves several stages:[16] from basic perceptual manipulations on the sensory information to derive details about the person (such as age, gender or attractiveness), to being able to recall meaningful details such as their name and any relevant past experiences of the individual.

This model (developed by psychologists Vicki Bruce and Andrew Young) argues that face perception might involve several independent sub-processes working in unison.

  1. A "view centered description" is derived from the perceptual input. Simple physical aspects of the face are used to work out age, gender or basic facial expressions. Most analysis at this stage is on feature-by-feature basis. That initial information is used to create a structural model of the face, which allows it to be compared to other faces in memory, and across views. This explains why the same person seen from a novel angle can still be recognized. This structural encoding can be seen to be specific for upright faces as demonstrated by the Thatcher effect. The structurally encoded representation is transferred to notional "face recognition units" that are used with "personal identity nodes" to identify a person through information from semantic memory. The natural ability to produce someone's name when presented with their face has been shown in experimental research to be damaged in some cases of brain injury, suggesting that naming may be a separate process from the memory of other information about a person.

The study of prosopagnosia (an impairment in recognizing faces which is usually caused by brain injury) has been particularly helpful in understanding how normal face perception might work. Individuals with prosopagnosia may differ in their abilities to understand faces, and it has been the investigation of these differences which has suggested that several stage theories might be correct.

Face perception is an ability that involves many areas of the brain; however, some areas have been shown to be particularly important. Brain imaging studies typically show a great deal of activity in an area of the temporal lobe known as the fusiform gyrus, an area also known to cause prosopagnosia when damaged (particularly when damage occurs on both sides). This evidence has led to a particular interest in this area and it is sometimes referred to as the fusiform face area for that reason.[17]

Neuroanatomy of facial processing

There are several parts of the brain that play a role in face perception. Rossion, Hanseeuw, and Dricot[18] used BOLD fMRI mapping to identify activation in the brain when subjects viewed both cars and faces. The majority of BOLD fMRI studies use blood oxygen level dependent (BOLD) contrast to determine which areas of the brain are activated by various cognitive functions.[19] They found that the occipital face area, located in the occipital lobe, the fusiform face area, the superior temporal sulcus, the amygdala, and the anterior/inferior cortex of the temporal lobe, all played roles in contrasting the faces from the cars, with the initial face perception beginning in the fusiform face area and occipital face areas. This entire region links to form a network that acts to distinguish faces. The processing of faces in the brain is known as a "sum of parts" perception.[20] However, the individual parts of the face must be processed first in order to put all of the pieces together. In early processing, the occipital face area contributes to face perception by recognizing the eyes, nose, and mouth as individual pieces.[21] Furthermore, Arcurio, Gold, and James[22] used BOLD fMRI mapping to determine the patterns of activation in the brain when parts of the face were presented in combination and when they were presented singly. The occipital face area is activated by the visual perception of single features of the face, for example, the nose and mouth, and preferred combination of two-eyes over other combinations. This research supports that the occipital face area recognizes the parts of the face at the early stages of recognition. On the contrary, the fusiform face area shows no preference for single features, because the fusiform face area is responsible for "holistic/configural" information,[23] meaning that it puts all of the processed pieces of the face together in later processing. This theory is supported by the work of Gold et al.[20] who found that regardless of the orientation of a face, subjects were impacted by the configuration of the individual facial features. Subjects were also impacted by the coding of the relationships between those features. This shows that processing is done by a summation of the parts in the later stages of recognition.

Facial perception has well identified, neuroanatomical correlates in the brain. During the perception of faces, major activations occur in the extrastriate areas bilaterally, particularly in the fusiform face area (FFA), the occipital face area (OFA), and the superior temporal sulcus (fSTS).[24][25]

The FFA is located in the lateral fusiform gyrus. It is thought that this area is involved in holistic processing of faces and it is sensitive to the presence of facial parts as well as the configuration of these parts. The FFA is also necessary for successful face detection and identification. This is supported by fMRI activation and studies on prospagnosia, which involves lesions in the FFA.[24][25][26]

The OFA is located in the inferior occipital gyrus.[25] Similar to the FFA, this area is also active during successful face detection and identification, a finding that is supported by fMRI activation.[24] The OFA is involved and necessary in the analysis of facial parts but not in the spacing or configuration of facial parts. This suggests that the OFA may be involved in a facial processing step that occurs prior to the FFA processing.[24]

The fSTS is involved in recognition of facial parts and is not sensitive to the configuration of these parts. It is also thought that this area is involved in gaze perception.[27] The fSTS has demonstrated increased activation when attending to gaze direction.[24]

Bilateral activation is generally shown in all of these specialized facial areas.[28][29][30][31][32][33] However there are some studies that include increased activation in one side over the other. For instance McCarthy (1997) has shown that the right fusiform gyrus is more important for facial processing in complex situations.[26]

Gorno-Tempini and Price have shown that the fusiform gyri are preferentially responsive to faces, whereas the parahippocampal/lingual gyri are responsive to buildings.[34]

It is important to note that while certain areas respond selectively to faces, facial processing involves many neural networks. These networks include visual and emotional processing systems as well. Emotional face processing research has demonstrated that there are some of the other functions at work. While looking at faces displaying emotions (especially those with fear facial expressions) compared to neutral faces there is increased activity in the right fusiform gyrus. This increased activity also correlates with increased amygdala activity in the same situations.[35] The emotional processing effects observed in the fusiform gyrus are decreased in patients with amygdala lesions.[35] This demonstrates possible connections between the amygdala and facial processing areas.[35]

Another aspect that affects both the fusiform gyrus and the amygdala activation is the familiarity of faces. Having multiple regions that can be activated by similar face components indicates that facial processing is a complex process.[35]

Ishai and colleagues have proposed the object form topology hypothesis, which posits that there is a topological organization of neural substrates for object and facial processing.[36] However, Gauthier disagrees and suggests that the category-specific and process-map models could accommodate most other proposed models for the neural underpinnings of facial processing.[37]

Most neuroanatomical substrates for facial processing are perfused by the middle cerebral artery (MCA). Therefore, facial processing has been studied using measurements of mean cerebral blood flow velocity in the middle cerebral arteries bilaterally. During facial recognition tasks, greater changes in the right middle cerebral artery (RMCA) than the left (LMCA) have been observed.[38][39] It has been demonstrated that men were right lateralized and women left lateralized during facial processing tasks.[40]

Just as memory and cognitive function separate the abilities of children and adults to recognize faces, the familiarity of a face may also play a role in the perception of faces.[20] Zheng, Mondloch, and Segalowitz recorded event-related potentials in the brain to determine the timing of recognition of faces in the brain.[41] The results of the study showed that familiar faces are indicated and recognized by a stronger N250,[41] a specific wavelength response that plays a role in the visual memory of faces.[42] Similarly, Moulson et al.[43] found that all faces elicit the N170 response in the brain.

Hemispheric asymmetries in facial processing capability

The mechanisms underlying gender-related differences in facial processing have not been studied extensively.

Studies using electrophysiological techniques have demonstrated gender-related differences during a face recognition memory (FRM) task and a facial affect identification task (FAIT). The male subjects used a right, while the female subjects used a left, hemisphere neural activation system in the processing of faces and facial affect.[44] Moreover, in facial perception there was no association to estimated intelligence, suggesting that face recognition performance in women is unrelated to several basic cognitive processes.[45] Gender-related differences[46] may suggest a role for sex hormones. In females there may be variability for psychological functions[47] related to differences in hormonal levels during different phases of the menstrual cycle.[48]

Data obtained in norm and in pathology support asymmetric face processing.[49][50][51] Gorno-Tempini and others in 2001, suggested that the left inferior frontal cortex and the bilateral occipitotemporal junction respond equally to all face conditions. Some neuroscientists contend that both the left inferior frontal cortex (Brodmann area 47) and the occipitotemporal junction are implicated in facial memory.[52][53][54] The right inferior temporal/fusiform gyrus responds selectively to faces but not to non-faces. The right temporal pole is activated during the discrimination of familiar faces and scenes from unfamiliar ones.[55] Right asymmetry in the mid temporal lobe for faces has also been shown using 133-Xenon measured cerebral blood flow (CBF).[56] Other investigators have observed right lateralization for facial recognition in previous electrophysiological and imaging studies.[57]

The implication of the observation of asymmetry for facial perception would be that different hemispheric strategies would be implemented. The right hemisphere would be expected to employ a holistic strategy, and the left an analytic strategy.[58][59][60][61] In 2007, Philip Njemanze, using a novel functional transcranial Doppler (fTCD) technique called functional transcranial Doppler spectroscopy (fTCDS), demonstrated that men were right lateralized for object and facial perception, while women were left lateralized for facial tasks but showed a right tendency or no lateralization for object perception.[62] Njemanze demonstrated using fTCDS, summation of responses related to facial stimulus complexity, which could be presumed as evidence for topological organization of these cortical areas in men. It may suggest that the latter extends from the area implicated in object perception to a much greater area involved in facial perception.

This agrees with the object form topology hypothesis proposed by Ishai and colleagues in 1999. However, the relatedness of object and facial perception was process based, and appears to be associated with their common holistic processing strategy in the right hemisphere. Moreover, when the same men were presented with facial paradigm requiring analytic processing, the left hemisphere was activated. This agrees with the suggestion made by Gauthier in 2000, that the extrastriate cortex contains areas that are best suited for different computations, and described as the process-map model. Therefore, the proposed models are not mutually exclusive, and this underscores the fact that facial processing does not impose any new constraints on the brain other than those used for other stimuli.

It may be suggested that each stimulus was mapped by category into face or non-face, and by process into holistic or analytic. Therefore, a unified category-specific process-mapping system was implemented for either right or left cognitive styles. Njemanze in 2007, concluded that, for facial perception, men used a category-specific process-mapping system for right cognitive style, but women used same for the left.

Controversies

Template:Criticism section

File:Martian face viking cropped.jpg
Many people see a "face" in this satellite image of the Cydonia region on Mars, due to the human ability to perceive faces even in inanimate objects, a phenomenon known as pareidolia.

Cognitive neuroscientists Isabel Gauthier and Michael Tarr are two of the major proponents of the view that face recognition involves expert discrimination of similar objects (See the Perceptual Expertise Network). Other scientists, in particular Nancy Kanwisher and her colleagues, argue that face recognition involves processes that are face-specific and that are not recruited by expert discriminations in other object classes (see the domain specificity).

Studies by Gauthier have shown that an area of the brain known as the fusiform gyrus (sometimes called the "fusiform face area, (FFA)" because it is active during face recognition) is also active when study participants are asked to discriminate between different types of birds and cars,[63] and even when participants become expert at distinguishing computer generated nonsense shapes known as greebles.[64] This suggests that the fusiform gyrus may have a general role in the recognition of similar visual objects. Yaoda Xu, then a post doctoral fellow with Nancy Kanwisher, replicated the car and bird expertise study using an improved fMRI design that was less susceptible to attentional accounts.

The activity found by Gauthier when participants viewed non-face objects was not as strong as when participants were viewing faces, however this could be because we have much more expertise for faces than for most other objects. Furthermore, not all findings of this research have been successfully replicated, for example, other research groups using different study designs have found that the fusiform gyrus is specific to faces and other nearby regions deal with non-face objects.[65]

However, these failures to replicate are difficult to interpret, because studies vary on too many aspects of the method. It has been argued that some studies test experts with objects that are slightly outside of their domain of expertise. More to the point, failures to replicate are null effects and can occur for many different reasons. In contrast, each replication adds a great deal of weight to a particular argument. With regard to "face specific" effects in neuroimaging, there are now multiple replications with Greebles, with birds and cars,[66] and two unpublished studies with chess experts.[67][68]

Although it is sometimes found that expertise recruits the FFA (e.g. as hypothesized by a proponent of this view in the preceding paragraph), a more common and less controversial finding is that expertise leads to focal category-selectivity in the fusiform gyrus—a pattern similar in terms of antecedent factors and neural specificity to that seen for faces. As such, it remains an open question as to whether face recognition and expert-level object recognition recruit similar neural mechanisms across different subregions of the fusiform or whether the two domains literally share the same neural substrates. Moreover, at least one study argues that the issue as to whether expertise-predicated category-selective areas overlap with the FFA is nonsensical in that multiple measurements of the FFA within an individual person often overlap no more with each other than do measurements of FFA and expertise-predicated regions.[69] At the same time, numerous studies have failed to replicate them altogether.[citation needed] For example, four published fMRI studies have asked whether expertise has any specific connection to the FFA in particular, by testing for expertise effects in both the FFA and a nearby but not face-selective region called LOC (Rhodes et al., JOCN 2004; Op de Beeck et al., JN 2006; Moore et al., JN 2006; Yue et al. VR 2006). In all four studies, expertise effects are significantly stronger in the LOC than in the FFA, and indeed expertise effects were only borderline significant in the FFA in two of the studies, while the effects were robust and significant in the LOC in all four studies.[citation needed]

Therefore, it is still not clear in exactly which situations the fusiform gyrus becomes active, although it is certain that face recognition relies heavily on this area and damage to it can lead to severe face recognition impairment.

Ethnicity

Main article: cross-race effect

Differences in own- versus other-race face recognition and perceptual discrimination was first researched in 1914[70] Humans tend to perceive people of other races than their own to all look alike:

Other things being equal, individuals of a given race are distinguishable from each other in proportion to our familiarity, to our contact with the race as whole. Thus, to the uninitiated American all Asiatics look alike, while to the Asiatics, all White men look alike.[70]

This phenomenon is known as the cross-race effect, own-race effect, other-race effect, own race bias or interracial-face-recognition-deficit.[71] The effect occurs as early as 170ms in the brain with the N170 brain response to faces.[72] A meta-analysis, Mullen[citation needed] has found evidence that the other-race effect is larger among White subjects than among African American subjects, whereas Brigham and Williamson (1979, cited in Shepherd, 1981) obtained the opposite pattern. Shepherd also reviewed studies that found a main effect for race efface like that of the present study, with better performance on White faces,[73] other studies in which no difference was found,[74] and yet other studies in which performance was better on African American faces.[75] Overall, Shepherd reports a reliable positive correlation between the size of the effect of target race (indexed by the difference in proportion correct on same- and other-race faces) and self-ratings of amount of interaction with members of the other race, r(30) = .57, p < .01. This correlation is at least partly an artifact of the fact that African American subjects, who performed equally well on faces of both races, almost always responded with the highest possible self-rating of amount of interaction with white people (M = 4.75), whereas their white counterparts both demonstrated an other-race effect and reported less other-race interaction (M = 2.13); the difference in ratings was reliable, £(30) = 7.86, p < .01[76]

Further research points to the importance of other-race experience in own- versus other-race face processing (O'Toole et al., 1991; Slone et al., 2000; Walker & Tanaka, 2003). In a series of studies, Walker and colleagues showed the relationship between amount and type of other-race contact and the ability to perceptually differentiate other-race faces (Walker & Tanaka, 2003; Walker & Hewstone, 2006a,b; 2007). Participants with greater other-race experience were consistently more accurate at discriminating between other-race faces than were participants with less other-race experience.

In addition to other-race contact, there is suggestion that the own-race effect is linked to increased ability to extract information about the spatial relationships between different features.[77] Richard Ferraro writes that facial recognition is an example of a neuropsychological measure that can be used to assess cognitive abilities that are salient within African-American culture.[78] Daniel T. Levin writes that the deficit occurs because people emphasize visual information specifying race at the expense of individuating information when recognizing faces of other races.[79] Further research using perceptual tasks could shed light on the specific cognitive processes involved in the other-race effect.[76] The question if the own-race effect can be overcome was already indirectly answered by Ekman & Friesen in 1976 and Ducci, Arcuri, Georgis & Sineshaw in 1982. They had observed that people from New Guinea and Ethiopia who had had contact with white people before had a significantly better emotional recognition rate.

Studies on adults have also shown sex differences in face recognition. Men tend to recognize fewer faces of women than women do, whereas there are no sex differences with regard to male faces.[80]

In individuals with autism spectrum disorder

Autism spectrum disorder (ASD) is a comprehensive neural developmental disorder that produces many deficits including social, communicative,[81] and perceptual deficits.[82] Of specific interest, individuals with autism exhibit difficulties in various aspects of facial perception, including facial identity recognition and recognition of emotional expressions.[83][84] These deficits are suspected to be a product of abnormalities occurring in both the early and late stages of facial processing.[85]

Speed and methods

People with ASD process face and non-face stimuli with the same speed.[85][86] In typically developing individuals, there is a preference for face processing, thus resulting in a faster processing speed in comparison to non-face stimuli.[85][86] These individuals primarily utilize holistic processing when perceiving faces.[82] Contrastingly, individuals with ASD employ part-based processing or bottom-up processing, focusing on individual features rather than the face as a whole.[87][88] When focusing on the individual parts of the face, persons with ASD direct their gaze primarily to the lower half of the face, specifically the mouth, varying from the eye trained gaze of typically developing people.[87][88][89][90][91] This deviation from holistic face processing does not employ the use of facial prototypes, which are templates stored in memory that make for easy retrieval.[84][92]

Additionally, individuals with ASD display difficulty with recognition memory, specifically memory that aids in identifying faces. The memory deficit is selective for faces and does not extend to other objects or visual inputs.[84] Some evidence lends support to the theory that these face-memory deficits are products of interference between connections of face processing regions.[84]

Associated difficulties

The atypical facial processing style of people with ASD often manifests in constrained social ability, due to decreased eye contact, joint attention, interpretation of emotional expression, and communicative skills.[93] These deficiencies can be seen in infants as young as 9 months; specifically in terms of poor eye contact and difficulties engaging in joint attention.[85] Some experts have even used the term 'face avoidance' to describe the phenomena where infants who are later diagnosed with ASD preferentially attend to non-face objects over faces.[81] Furthermore, some have proposed that the demonstrated impairment in children with ASD's ability to grasp emotional content of faces is not a reflection of the incapacity to process emotional information, but rather, the result of a general inattentiveness to facial expression.[81] The constraints of these processes that are essential to the development of communicative and social-cognitive abilities are viewed to be the cause of impaired social engagement and responsivity.[94] Furthermore, research suggests that there exists a link between decreased face processing abilities in individuals with ASD and later deficits in Theory of Mind; for example, while typically developing individuals are able to relate others' emotional expressions to their actions, individuals with ASD do not demonstrate this skill to the same extent.[95]

There is some contention about this causation however, resembling the chicken or the egg dispute. Others theorize that social impairment leads to perceptual problems rather than vice versa.[87] In this perspective, a biological lack of social interest inherent to ASD inhibits developments of facial recognition and perception processes due to underutilization.[87] Continued research is necessary to determine which theory is best supported.

Neurology

Many of the obstacles that individuals with ASD face in terms of facial processing may be derived from abnormalities in the fusiform face area and amygdala, which have been shown to be important in face perception as discussed above. Typically, the fusiform face area in individuals with ASD has reduced volume compared to normally developed persons.[96] This volume reduction has been attributed to deviant amygdala activity that does not flag faces as emotionally salient and thus decreases activation levels of the fusiform face area. This hypoactivity in the in the fusiform face area has been found in several studies.[87]

Studies are not conclusive as to which brain areas people with ASD use instead. One study found that, when looking at faces, people with ASD exhibit activity in brain regions normally active when typically developing individuals perceive objects.[87] Another study found that during facial perception, people with ASD use different neural systems, with each one of them using their own unique neural circuitry.[96]

Compensation mechanisms

As ASD individuals age, scores on behavioral tests assessing ability to perform face-emotion recognition increase to levels similar to controls.[85][97] Yet, it is apparent that the recognition mechanisms of these individuals are still atypical, though often effective.[97] In terms of face identity-recognition, compensation can take many forms including a more pattern-based strategy which was first seen in face inversion tasks.[90] Alternatively, evidence suggests that older individuals compensate by using mimicry of other’s facial expressions and rely on their motor feedback of facial muscles for face emotion-recognition.[98] These strategies help overcome the obstacles individuals with ASD face in interacting within social contexts.

Artificial face perception

A great deal of effort has been put into developing software that can recognize human faces. Much of the work has been done by a branch of artificial intelligence known as computer vision which uses findings from the psychology of face perception to inform software design. Recent breakthroughs using noninvasive functional transcranial Doppler spectroscopy as demonstrated by Njemanze, 2007, to locate specific responses to facial stimuli have led to improved systems for facial recognition. The new system uses input responses called cortical long-term potentiation (CLTP) derived from Fourier analysis of mean blood flow velocity to trigger target face search from a computerized face database system.[99][100] Such a system provides for brain-machine interface for facial recognition, and the method has been referred to as cognitive biometrics.

Another interesting application is the estimation of human age from face images. As an important hint for human communication, facial images contain lots of useful information including gender, expression, age, etc. Unfortunately, compared with other cognition problems, age estimation from facial images is still very challenging. This is mainly because the aging process is influenced not only by a person's genes but also many external factors. Physical condition, living style etc. may accelerate or slow the aging process. Besides, since the aging process is slow and with long duration, collecting sufficient data for training is fairly demanding work.[101]

See also

References & Bibliography

Key texts

Books

  • Bruce, V. and Young, A. (2000) In the Eye of the Beholder: The Science of Face Perception. Oxford: Oxford University Press. ISBN 0198524390
  • Bruce, V. & Humphreys, G. W. (Eds.) (1994) Object and face processing. London: Erlbaum.


Papers

1Nelson, C.A. (2001) The development and neural bases of face recognition. Infant and Child Development, 10, 3-18.
2Bruce, V. & Young, A. (1986) Understanding face recognition. The British Journal of Psychology, 77 (3), 305-327.
3Kanwisher, NG, McDermott, J, Chun, MM. (1997) The fusiform face area: a module in human extrastriate cortex specialized for face perception. Journal of Neuroscience, 17 (11), 4302-11.
4Gauthier I, Skudlarski P, Gore JC, Anderson AW. (2000) Expertise for cars and birds recruits brain areas involved in face recognition. Nature Neuroscience, 3 (2), 191-7.
5Gauthier I, Tarr MJ, Anderson AW, Skudlarski P, Gore JC. (1999) Activation of the middle fusiform 'face area' increases with expertise in recognizing novel objects. Nature Neuroscience, 2 (6), 568-73.
6Grill-Spector K, Knouf N, Kanwisher N. (2004) The fusiform face area subserves face perception, not generic within-category identification. Nature Neuroscience, 7 (5), 555-62.
7Xu, Y. (2005). Revisiting the role of the fusiform and occipital face areas in visual expertise. Cerebral Cortex, 185, 1234-1242.

8Kargopoulos, P., Bablekou, Z., Gonida, E., & Kiosseoglou, G. (2003) Effects of face and name presentation on memory for associated verbal descriptors. The American Journal of Psychology, 116 (3), 415-430.

  • Bower, G.H. and Karlin, M.B. (1974) Depth of processing pictures of faces and recognition memory, Journal of Experimental Psychology 103: 751-7.
  • Bruce, V, and Young, A.W. (1986) Understanding face recognition, British Journal of Psychology 77: 305-27.
  • Ellis, H.D., Shepherd, J.W. and Davies, G.M. (1979) Identification of familiar and unfamiliar faces from internal and external features: some implications for theories of face recognition, Perception 8: 431-9.
  • Haig, N.D. (1984) The effect of feature displacement on face recognition, Perception 13: 505-12.
  • Servos. P., Engel, S. A., Gati, J. and Menon, R. (1999) fMRI evidence for an inverted face representation in human somatosensory cortex, NeuroReport, 10, 1393-95.

Additional material

Books

Papers

Ahrens, S.R. (1954) Beitrage zur Entwicklung des Physiognomie and Mimikerkennes {Contributions on the development of physiognomy and mimicry recognition], Zeitschrift fur Experimentelle and Angewandre Psychologie 2: 412-54.

  • Goren, C.C., Sarty, M. and Wu, R.W.K. (1975) Visual following and pattern discrimination of face-like stimuli by new-born infants, Paediatrics 56: 544-9.
  • Valentine, T. (1985) Identity priming in the recognition of familiar and unfamiliar faces, British Journal of Psychology 76: 373-83.

External links

  • FaceResearch – Scientific research and online studies on face perception
  • Facial Expression Resources Page Links to research groups and other resources concerning facial expression perception, recognition and synthesis.
  • Face Blind Prosopagnosia Research Centers at Harvard and University College London
  • Perceptual Expertise Network (PEN) Collaborative group of cognitive neuroscientists studying perceptual expertise, including face recognition.
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