Psychology Wiki
Register
Tag: Visual edit
 
(3 intermediate revisions by 2 users not shown)
Line 1: Line 1:
 
{{expPsy}}
 
{{expPsy}}
  +
'''Inattentional Blindness''' is the event in which an individual fails to recognize an unexpected stimulus that is in plain sight. The term inattentional blindness was coined by [[Arien Mack]] and [[Irvin Rock]] in 1992 and was used as the title of Mack and Rock's book published by [[MIT Press|MIT press]] in 1998. Here, they describe the discovery of Inattentional Blindness and include a collection of procedures used in exemplifying the phenomenon.<ref name="Rock, 1992"/> Research on inattentional blindness, also sometimes referred to as '''perceptual blindness''', suggests that this phenomenon can occur in all individuals, independent of [[Cognition|cognitive]] deficits. It is simply impossible for one to attend to all the visual stimuli in a visual field, and as a result, a temporary "blindness" effect can take place. That is, individuals fail to see objects or stimuli that are unexpected and quite often salient.
{{Expansion}}
 
 
:''This article discusses the [[psychology|psychological]] concept of ''Inattentional Blindness'''.''
 
   
  +
The following criteria are required to classify an event as an inattentional blindness episode: 1) the observer must fail to notice a visual object or event, 2) the object or event must be fully visible, 3) observers must be able to readily identify the object if they are consciously perceiving it,<ref name="Rock, 1992">Rock, I., Linnet, C. M., Grant P.I., & Mack, A. (1992). Perception without attention: Results of a new method. Cognitive Psychology, 24, 502-534.</ref> and 4) the event must be unexpected and the failure to see the object or event must be due to the engagement of attention on other aspects of the visual scene and not due to aspects the visual stimulus itself.<ref name="Rock, 1992"/> Individuals who experience inattentional blindness are usually unaware of this effect, which can play a subsequent role on behavior.
 
 
  +
Inattentional blindness is related to but distinct from other failures of visual awareness such as [[change blindness]], [[repetition blindness]], visual masking, and [[attentional blink]]. The key aspect of inattentional blindess which makes it distinct from other failures in [[awareness]] rests on the fact that the undetected stimulus is unexpected.<ref name="driver,1998"/> It is the unexpected nature of said stimulus that differentiates inattentional blindness from failures of awareness such as attentional failures like the aforementioned attentional blink. It is critical to acknowledge that occurrences of inattentional blindness are attributed to the failure to consciously attend to an item in the visual field as opposed the absence of [[Information_processing_theory#Cognitive_processes|cognitive processing]].
'''Inattentional blindness''', closely related to the subject of [[change blindness]], is observed phenomena of the inability to perceive features in a visual scene if they are not being attended to. That is to say that humans have a limited capacity for [[attention]] which thus limits the amount of information processed at any particular time. Any otherwise salient feature within the visual field will not be observed if not processed by attention.
 
   
  +
Findings such as inattentional blindness - the failure to notice a fully visible but unexpected object because attention was engaged on another task, event, or object - has changed views on how the brain stores and integrates visual information, and has led to further questioning and investigation of the brain and importantly of [[Cognition|cognitive]] processes.
==Experiments demonstrating inattentional blindness==
 
The most well known study demonstrating inattentional blindness was conducted by [[Daniel Simons]] of the [[University of Illinois at Urbana-Champaign]] and [[Christopher Chabris]] of [[Harvard University]]. In their study, subjects are asked to watch a short video [http://viscog.beckman.uiuc.edu/grafs/demos/15.html] in which two groups of people (wearing black and white t-shirts) pass a basketball back among themselves. The subjects are told to either count the number of passes made by one of the teams, or to keep count of bounce passes vs. aerial passes.
 
In different versions of the video a woman walks through the scene carrying an umbrella, or wearing a full gorilla suit. In one version the woman in the gorilla suit even stops in the middle, faces the camera, and pounds her chest before walking out of the scene.
 
After watching the video the subjects are asked if they saw anything out of the ordinary take place. In most groups 50% of the subjects did not report seeing the gorilla.
 
Simons interprets this by stating that we are mistaken with regard to how important events will automatically draw our attention away from current tasks or goals. This result indicates that the relationship between what is in our visual field and perception is based much more significantly on attention than was previously thought.
 
   
  +
==The Cognition Debate - Early vs. Late Selection of Attention==
Another research finding was done by Steve Most, Chabis and Scholl. They had objects moving up and down on a computer screen. Participants were instructed to attend to
 
  +
One of the most foremost conflicts among researchers of inattentional blindness surrounds the [[Information_processing_theory#Cognitive_processes|processing]] of unattended stimuli. More specifically, there is disagreement in the literature about exactly how much processing of a visual scene is completed before selection dictates which stimuli will be [[Consciousness|consciously]] perceived, and which will not (i.e. Inattentional Blindness). There exists two basic schools of thought on the issue - those who believe selection is done early in the perceptual process, and those who believe it is done only after significant processing.<ref name="Spinks2004">Spinks. J.A., Zhang, J.X., Fox, P.T., Gao, J-H., & Tan, L.H. (2004). More workload on the central executive of working memory, less attention capture by novel visual distractors: evidence from an fMRI study. NeuroImage, 23, 517-524</ref> Early selection theorists propose that perception of stimuli is a limited process requiring selection to proceed. This suggests that the decision to attend to specific stimuli occurs early in processing, soon after the rudimentary study of physical features; only those selected stimuli are then fully processed. On the other hand, proponents of late selection theories argue that [[perception]] is an unlimited operation, and all stimuli in a visual scene are [[Parallel processing|processed simultaneously]]. In this case, selection of relevant information is done after full processing of all stimuli.<ref name="Lavie1994">Lavie, N., & Tsal, Y. (1994). Perceptual load as a major determinant of the locus of selection in visual attention. Perception & Psychophysics, 56(2), 183-197</ref>
the black objects and ignore the white,
 
or vice versa. After several trials, a red
 
cross unexpectedly appeared and traveled
 
across the display, remaining on the
 
computer screen for five seconds.
 
The results of the experiment
 
showed that even though the cross was
 
distinctive from the black and white
 
objects both in color and shape, about a
 
third of participants nonetheless missed
 
it. They had found that people may be attentionally
 
tuned to certain perceptual dimensions,
 
such as brightness or shape.
 
   
  +
While early research on the topic was heavily focused on early selection, research since the late 1970s has shifted mainly to the late selection theories. This change resulted primarily from a shift in paradigms used to study inattentional blindness which revealed new aspects of the phenomenon.<ref>Kahneman, D., & Treisman, A. (1984). Changing views of attention and automacity. In R. Parasuraman & D.R Davies (Eds.), Varieties of Attention (pp. 29-61). New York: Academic Press</ref> Today, late selection theories are generally accepted, and continue to be the focus of the majority of research concerning inattentional blindness.
Thus the common saying "out of sight, out of mind", meaning that people usually don't think about what they do not see, could be reversed into: "out of mind, out of sight".
 
   
  +
===Evidence for Late Selection===
==Current research==
 
  +
A significant body of research has been gathered in support of late selection in the perception of visual stimuli.
The latest finding was produced by Most, Scholl, Clifford and Simons (2005). There seems to be strong support for the attentional resources to be mediated by the attentional set.
 
Chun & Marois are also a good review.
 
   
  +
One of the popular ways of investigating late selection is to assess the [[Priming (psychology)|priming]] properties (i.e. influencing subsequent acts<ref name="Mack2003">Mack, A. (2003). Inattentional blindness: Looking without seeing. Current Directions in Psychological Science, 12(5), 180-184.</ref>) of unattended stimuli. Often used to demonstrate such effects is the stem completion task. While there exist a few variations, these studies generally consist of showing participants the first few letters of words, and asking them to complete the string of letters to form an English word.<ref name="Mack2003"/> It has been demonstrated that observers are significantly more likely to complete word fragments with the unattended stimuli presented in a trial than with another similar word.<ref name="Mack1998">Mack, A. and Rock, I. (1998). Inattentional Blindness, MIT Press</ref> This effect holds when stimuli are not words, but instead objects. When photos of objects are shown too quickly for participants to identify, subsequent presentation of those items lead to significantly faster identification in comparison to novel objects.<ref name="Mack2003"/>
==Human attention==
 
{{Expandsect}}
 
   
  +
An interesting study by Mack and Rock has also revealed that showing a word stimulus differing from the participant's name by one letter did not generally call conscious attention. By simply changing a character, transforming the presented word into the observer's first name, the now highly meaningful stimulus is significantly more likely to be attended to. This suggests that the stimuli are being extensively processed, at least enough to analyze their meaning. These results point to the fact that attentional selection may be determined late in processing.<ref name="Mack1998"/>
==See also==
 
   
  +
The evidence outlined above suggests that even when stimuli are not processed to the level of conscious attention, they are nonetheless perceptually and cognitively processed, and can indeed exert effects on subsequent behavior.<ref name="Mack2001">Mack, A. (2001). Inattentional blindness: Reply to commentaries. Psyche, 7(16), 1-7.</ref>
==References & Bibliography==
 
   
  +
===Evidence for Early Selection===
==Key texts==
 
  +
While the evidence supporting late selection hypotheses is significant and has been consistently reproduced, there also exists a body of research suggesting that unattended stimuli in fact may not receive significant processing.
===Books===
 
===Papers===
 
 
==Additional material==
 
===Books===
 
===Papers===
 
*[http://scholar.google.com/scholar?sourceid=mozclient&num=50&scoring=d&ie=utf-8&oe=utf-8&q=Inattentional+blindness Google Scholar]
 
   
  +
For example, in an [[Functional magnetic resonance imaging|fMRI]] study by Rees and colleagues, brain activity was recorded while participants completed a perceptual task. Here they examined the neural processing of meaningful (words) and meaningless (consonant string) stimuli both when attended to, and when these same items were unattended. While no difference in activation patterns were found between the groups when the stimuli were unattended, differences in neural processing were observed for meaningful versus meaningless stimuli to which participants overtly attended. This pattern of results suggests that ignored stimuli are not processed to the level of meaning, i.e. less extensively than attended stimuli.<ref>Rees, G., Russell, C., Firth, C., & Driver, J. (1999). Inattentional blindness versus inattentional amnesia. Science, 286, 849-860.</ref> Participants do not seem to be detecting meaning in stimuli to which they are not consciously attending.
==External links==
 
*[http://www.wjh.harvard.edu/%7Ecfc/Simons1999.pdf Gorillas in our midst: sustained inattentional blindness for dynamic events]
 
   
  +
==Theories of Inattentional Blindness==
*[http://viscog.beckman.uiuc.edu/djs_lab/ Visual Cognition Lab University of Illinois]
 
  +
===Perceptual Load===
  +
This particular hypothesis bridges the gap between the early and late selection theories. Authors integrate the viewpoint of early selection stating that perception is a limited process (i.e. cognitive resources are limited), and that of the late selection theories assuming perception as an automatic process.<ref name="Lavie1994" />
  +
This view proposes that the level of processing which occurs for any one stimulus is dependent on the current perceptual load. That is, if the current task is attentionally demanding and its processing exhausts all the available resources, little remains available to process other non-target stimuli in the visual field. Alternatively, if processing requires a small amount of attentional resources, perceptual load is low and attention is inescapably directed to the non-target stimuli.<ref name="Spinks2004"/>
   
  +
The effects of perceptual load on the occurrence of inattentional blindness is elegantly demonstrated in a study by Fougnie and Marois. Here, participants were asked to complete a memory task involving either the simple maintenance of verbal stimuli, or the rearrangement of this material, a more cognitively demanding exercise. While subjects were completing the assigned task, an unexpected visual stimulus was presented. Results revealed that unexpected stimuli were more likely to be missed during manipulation of information than in the more simple rehearsal task.<ref>Fougnie, D., & Marois, R. (2007). Executive working memory load induces inattentional blindness. Psychonomic Bulletin & Review, 14(1), 142-147.</ref>
*[http://news.nationalgeographic.com/news/2005/08/0822_050822_chinese.html Chinese, Americans Truly See Differently, Study Says]
 
   
  +
In a similar type of study, fMRI recordings were done while subjects took part in either low-demand or high-demand subtraction tasks. While performing these exercises, novel visual distractors were presented. When task demands were low and used a smaller portion of the finite resources, distractors captured attention and sparked visual analysis as shown by brain activation in the [[Visual cortex|primary visual cortex]]. These results, however, did not hold when perceptual load was high; in this condition, distractors were significantly less often attended to and processed.<ref name="Spinks2004"/>
*[http://hvattum.net/wp/?p=3 Can you trust your mind? Take the test]
 
   
  +
Thus, higher perceptual load, and therefore more significant use of attentional resources, appears to increase the likelihood of inattentional blindness episodes.
* [http://consc.net/online3.html#change Change Blindness and Inattentional Blindness]
 
  +
  +
===Inattentional Amnesia===
  +
The theory of inattentional amnesia provides an interesting alternative in the explanation of inattentional blindness. It suggests that this phenomenon does not stem from failures in capture of attention or in actual perception of stimuli, but instead from a failure in memory. The unnoticed stimuli in a visual scene are attended to and consciously perceived, but are rapidly forgotten rendering them impossible to report.<ref>Simons, D.J. (2000). Attentional capture and inattentional blindness. Trends in Cognitive Science, 4(4), 147-155.</ref> In essence, inattentional amnesia refers to the failure in creating a lasting explicit memory; by the time a subject is asked to recall seeing an item, their memory for the stimulus has vanished.<ref>Wolfe, J.M. (1999). Inattentional amnesia. In V. Coltheart (Ed.), Fleeting Memories (pp.71-94). Cambridge, MA: MIT Press.</ref>
  +
  +
While it is difficult to tease apart a failure in perception from one in memory, some research has attempted to shed light on the issue. In a classic study of inattentional blindness, a woman carrying an umbrella through a scene goes unnoticed. Despite stopping the video while she is walking through and immediately asking participants to identify which of two people they have seen - leaving as little delay as possible between presentation and report - observers very often fail to correctly identify the woman with the umbrella. No differences in performance were identified whether the video was stopped immediately after the unexpected event or moments later. These findings would seem to oppose the idea of inattentional amnesia, however advocates of the theory could always contend that the memory test simply came too late and that the memory had already been lost.<ref>Becklen, R., & Cervone, D. (1983). Selective looking and the noticing of unexpected events. Memory & Cognition, 11(6), 601-608.</ref>
  +
  +
===Expectation===
  +
The very phenomenon of Inattentional blindness is defined by a lack of expectation for the unattended stimulus. Some researchers believe that it is not inattention that produces blindness, but in fact the aforementioned lack of expectation for the stimuli.<ref name="Mack2001"/> Proponents of this ideology often state that classic methods for testing inattentional blindness are not manipulating attention per se, but instead the expectation for the presentation of a visual item.<ref>Braun, J. (2001). Its great but not necessarily about attention. Psyche, 7(6), 1-7.</ref>
  +
  +
Studies investigating the effect of expectation on episodes of inattentional blindness have shown that once observers are made aware of the importance of the to be presented stimuli, for example stating that one will later be tested on it, the phenomenon essentially disappears.<ref name="Mack1998"/> While admitting to possible ambiguities in methodology, Mack, one of the foremost researchers in the field, holds strongly that inattentional blindness stems predominantly from a failure of attentional capture. He points out that if expectation does not mediate instances of very closely linked phenomena such as [[attentional blink]] and [[change blindness]] (whereby participants have difficulty identifying the changing object even when they are explicitly told to look for it), it is unlikely that inattentional blindness can be explained solely by a lack of expectation for stimulus presentation.<ref name="Mack2001"/>
  +
  +
==Classic Experiments Demonstrating Inattentional Blindness==
  +
===Invisible Gorilla Test===
  +
The '''Invisible Gorilla Test''' is one of the most widely known experiments pertaining to inattentional blindness. It was done by Daniel Simmons from the [[University of Illinois at Urbana–Champaign]] and Christopher Chabris from [[Harvard University]]. Their study was a revised version of earlier studies conducted by [[Ulric Neisser]] and Becklen in 1975. It consists of asking participants to look at a video of two teams, one black and one white, with three people on each. The participants are asked to count how many times a basketball is passed between members of the white team. While this is happening, a person dressed in a gorilla costume walks and stands in front of the camera, thumps its chest, then walks off camera. It is on screen for about 9 seconds. After watching the video, the participants are asked if they noticed anything out of the ordinary, and about half of them were so focused on counting, also known as [[Attention#Selective_Attention|selective attention]], that they did not notice other stimulus in their eyesight, the gorilla. There are also other versions of this experiment, in which a woman walks through the scene carrying an umbrella, or in which the participants are asked to only count either aerial passes or only bounce passes.<ref>Chabris, C. Clifford, E. Jimenez, R. Most, S. Scholl, B. Simons, D. (2001) "How Not to be Seen: The Contribution of Similarity and Selective Ignoring to Sustained Inattentional Bindness." Psychological Science. Vol 12 No. 1.</ref> In a subsequent and similar study by Daniel Memmert, the gorilla video was used but in addition, the eye movements and fixations of the participants were recorded and analyzed. It was found that the participants who failed to perceive the gorilla still spent about 25 frames or a total of one second fixated on it.<ref name="Memmert"/>
  +
  +
This classic study is a clear example of how people can fail to perceive a stimulus that is fully visible when their [[attention]] is focused on a different task, and as shown in the following example, inattentional blindness is applicable to real-life situations as well.
  +
  +
===Perception and Inattentional Blindness-A Real-world Experiment===
  +
In 1995, Officer Kenny Conley was chasing a shooting suspect. An undercover officer was in the same vicinity and was mistakenly taken down by other officers while Conely ran by and failed to notice. A jury later convicted Officer Conley believing he had seen the fight, yet he stood by his word that he had, in fact, not seen it.
  +
  +
Christopher Chabirs, Adam Weinberger, Matthew Fontain and Daniel J. Simons took it upon themselves to see if this scenario was possible. They designed an experiment in which participants were asked to run about 30 feet behind Officer Conley himself, and count how times he touched his head. A fight was staged to appear about 8 meters off the path, and was visible for approximately 15 seconds. The procedure in its entirety lasted about 2 minutes and 45 seconds, and participants were then asked to report the number of times they had seen Officer Conley touch his head with either hand (medium load), both hands (high load), or were not instructed to count at all (low load). After the run, participants were asked 3 questions: 1) If they had noticed the fight; 2) if they had noticed a juggler, and 3) if they had noticed someone dribbling a basketball. Questions 2) and 3) were control questions, and no one falsely reported these as true.
  +
  +
Participants were significantly more likely to notice the fight when the experiment was done during the day as opposed to in the dark. Additionally, sightings of the fight were most likely to be reported in the low load condition (72%) than in either the medium load (56%), or high load conditions (42%).<ref>Chabris, C. Fontaine, M. Simmons, D. Weinberger, A. (2011) “You do Not Talk About Fight Club if You Do Not Notice Fight Club: Inattentional Blindness For A Stimulated Real-World Assult.” i-Perception. 2: 150-153</ref> These results exemplify a real world occurrence of inattentional blindness, and provide evidence that officer Conley could indeed have missed the fight because his attention was focused elsewhere. Moreover, these results add to the body of knowledge suggesting that as perceptual load increases, less resources remain to process items not explicitly focused on, and in turn episodes of inattentional blindness become more frequent.
  +
  +
==Limitations of Perception or Memory?==
  +
Arien Mack and Irvin Rock’s findings on inattentional blindness is summarized in their 1988 book which comes to the generalized conclusion that no conscious perception can occur without attention.<ref name=Mack1998 /> Evidence through research on inattentional blindness contemplates that it may be possible that inattentional blindness reflects a problem with memory rather than with perception.<ref name=Mack1998 /> It is argued that at least some instances of inattentional blindness are better characterized as memory failures then perceptual failures. The extent to which unattended stimuli fail to engage perceptual processing is an empirical question that the combination of inattentional blindness and other various measures of processing can be used to address.<ref name="Rock, 1992" />
  +
  +
The theory behind inattentional blindness research suggests that we consciously experience only those objects and events to which we directly attend.<ref name=Mack1998 /> That means that the vast majority of information in our field of vision goes unnoticed. Thus if we miss the target stimulus in an experiment, but are later told about the existence of the stimulus, this sufficient awareness allows participants to report and recall the stimulus now that attention has been allocated to it.<ref name="Rock, 1992" /> Mack and Rock, and their colleagues discovered a striking array of visual events to which people are inattentionally blind.<ref name=Mack1998 /> However the debate arises whether this inattentional blindness was due to memory or perceptual processing limitations.
  +
  +
Mack and Rock note that explanations for inattentional blindness can reflect a basic failure of perceptual processes to be engaged by unattended stimuli. Or that it may reflect a failure of memorial processes to encode information about unattended stimuli. It is important to note that the memory failure does not have to do with forgetting something that has been encoded by losing access to the memory of the stimulus from time of presentation to time of retrieval, rather that the failure is attributed to information not being encoded when the stimulus was present.<ref name=Mack1998 /> It seems that inattentional blindness can be explained by both memory and perceptual failures because in experimental research participants may fail to report what was on display due to failures in encoded information (memory) or a failure in perceptually processed information (perception).<ref name=Mack1998 />
  +
  +
==Neuropsychological analogies of Inattentional Blindness==
  +
There are similarities in the types of unconscious processing apparent in inattentional blindness and in neuropsychological syndromes such as visual neglect and extinction. The analogy between these phenomenon’s seems to generate more questions as well as answers. These answers are fundamental for our understanding of the relationship between attention, stimulus coding and behavior.
  +
  +
===Visual neglect===
  +
Research has shown that some aspects of the syndrome of unilateral '''visual neglect''' appear to be similar to normal subjects in a state of inattentional blindness. In neglect, patients with lesions to the [[parietal cortex]] fail to respond to and report stimuli presented on the side of space [http://en.wiktionary.org/wiki/contralateral contralateral] to damage.
  +
[[File:Parietal lobe animation small.gif|thumb|left|Animation. Parietal lobe (red) of left cerebral hemisphere.|link=Special:FilePath/Parietal_lobe_animation_small.gif]]
  +
<ref name="Mack2001"/><ref>Moore, C. M., & Egeth, H. (1997). Perception without attention: Evidence of grouping under conditions of inattention. Journal of Experimental Psychology: Human Perception and Performance, 23, 339-352.</ref> That is, they appear to be functionally blind to a range of stimuli. Since such lesions do not result in any sensory deficits, shortcomings have been explained in terms of a lack of attentional processing, for which the parietal cortex plays a large role.<ref>Rafal, R. (1998). Neglect. In R. Parasuraman (Ed.), The Attentive Brain (pp.489-526). Cambridge. MA: MIT Press.</ref>
  +
These phenomena draw strong parallels to one another, as in both cases stimuli are perceptible but unreported when unattended.
  +
  +
===Extinction===
  +
In the phenomenon of '''extinction''', patients can report the presence of a single stimulus presented on the affected side, but then fail to detect it when a second stimulus is presented simultaneously on the 'good' ([http://en.wiktionary.org/wiki/ipsilateral ipsilateral]) side.<ref name="humphreys,1994">Humphreys, G.W., Romani, C., Olson, A., Riddoch, M.J. & Duncan, J. (1994). Non- spatial extinction following lesions of the parietal lobe in humans. Nature, 372, 357-359.</ref> Here the stimulus on the affected side seems to lose under conditions of attentional competition from stimuli in the ipsilesional field.<ref name="humphreys,1994"/> The consequence of this competition is that the extinguished items may not be detected.
  +
  +
Similar to studies of inattentional blindness, there is evidence of processing taking place in the neglected field. For example, there can be semantic priming from a stimulus presented in the neglected field, which affects responses to stimuli subsequently presented on the unimpaired side.<ref name="MR">Mack, A., Tang, B., Tuma, R., & Rock, I. (1992). Perceptual organization and attention. Cognitive Psychology, 24, 475-501.</ref> Apparently in both neglect and inattentional blindness, there is some level processing of stimuli even when they are unattended.<ref name="MR"/> However one major difference between neuropsychological symptoms such as neglect and extinction, and inattentional blindness concerns the role of expectation.<ref name="MR"/> In inattentional blindness, subjects do not expect the unreported stimulus. In contrast, in neglect and extinction, patients may expect a stimulus to be presented on the affected side but still fail to report it when another it may be that expectation affects reportability but not the implicit processing of stimuli.<ref name="MR"/>
  +
  +
Further explanations of the phenomenon of inattentional blindness include inattentional amnesia, inattentional agnosia and change blindness.
  +
  +
===Inattentional Agnosia===
  +
An explanation for this phenomenon is that observers see the critical object in their visual field but fail to process it extensively enough to retain it . Individuals experience '''Inattentional Agnosia''' after having seen the target stimuli but not consciously being able to identify what the stimuli is. It is possible that observers are not even able to identify that the stimuli they are seeing are coherent objects.<ref>Neisser, U. (1967). Cognitive psychology. New York: Appleton-Century-Crofts.</ref> Thus observers perceive some representation of the stimuli but are actually unaware of what that stimulus is. It is because the stimulus is not encoded as a specific thing, that it later is not remembered. Individuals fail to report what the stimuli is after it has been removed. However, despite a lack in ability to fully process the stimuli, experiments have shown a priming effect of the critical stimuli. This priming effect indicates that the stimuli must have been processed to some degree, this occurs even if observers are unable to report what the stimuli is.<ref>Yantis, S. (1999). Seeing is attending. Contemporary Psychology, 44, 314-316.</ref>
  +
  +
===Change Blindness===
  +
Inattentional blindness is the failure to see a stimulus, such as an object that is present in a visual field. However, '''Change Blindness''' is the failure to notice something different about a visual display. Change blindness is directly related to memory, individuals who experience the effects of change blindness fail to notice something different about a visual display from one moment to the next.<ref name="driver,1998">Driver, J. (1998). The neuropsychology of spatial attention. In H. Pashler (Ed.), Attention. (pp. 297-340). London: Taylor Francis</ref> In experiments that test for this phenomenon participants are shown an image that is then followed by another duplicate image that has had a single change made to it. Participants are asked to compare and contrast the two images and identify what the change is. In inattentional blindness experiments, participants fail to identify some stimulus in a single display, a phenomenon that doesn’t rely on memory the way change blindness does.<ref name="driver,1998"/> Inattentional blindness refers to an inability to identify an object all together where as change blindness is a failure to compare a new image or display to one that was previously stored in memory.<ref name="driver,1998"/>
  +
  +
==Additional Factors Exhibiting Effects on Inattentional Blindness==
  +
===Age and Expertise===
  +
In 2006, Daniel Memmert conducted a series of studies in which he tested the how age and expertise of participants affect inattentional blindness. Using the gorilla video, he tested 6 different groups of participants. There were 2 groups of children (average age=7) half with no experience in basketball, and the other half with 2 years experience; 2 groups of juniors (average age=13) half with no experience in basketball, and the other half with 5 years of experience; and 2 groups of adults (average age = 24) half with no experience in basketball, the other half with over 12 years of experience. He then instructed all the groups to keep track of how many passes the people on the black team made.
  +
  +
Overall, the children with or without any basketball experience failed to perceive the gorilla more than the juniors or the adults. There were no significant difference between the inexperienced junior and adult groups, or between the experienced junior and adult groups.<ref name="Memmert">Memmert, D. (2006). The effects of eye movement, age, and expertise on inattentional blindness. Consciousness and cognition, vol 15, 620-627.</ref> This pattern of results suggests that until the approximate age of 13, presumably because certain aspects of cognition are still under development, inattentional blindness occurrences are more frequent, but become consistent throughout the remainder of the life span.
  +
  +
Additionally, the juniors with basketball experience noticed the gorilla significantly more than the juniors with no basketball experience; and the group of experienced adults noticed the gorilla significantly more than the non-experienced adults. This suggests that if one has had much experience with the stimuli in a visual field, they are more likely to consciously perceive the unexpected object.
  +
  +
===Similarity Between Stimuli===
  +
A series of studies conducted to test how similarity can influence the [[perception]] of a present stimulus. In the study, they asked participants to fixate on a central point on a computer screen and count how many times either white or black letters bounced off the edges of the screen. The first 2 trials did not contain an unexpected event, but the third trial was the critical trial in which a cross that had the same dimensions as the letters and varied in colour (white/light gray/dark gray/black) moved from the right side of the screen to the left side and passed through the central point. The results revealed the following: during the critical event, the more similar the colour of the cross was to the colour of the attended letters, the more likely the participants were to perceive it, and the less similar the colour of the cross was to the attended colour decreased the likelihood of the cross being noticed. For the participants attending to the black letters, 94% perceived the black cross; 44% perceived the dark gray cross; 12% perceived the light gray cross, and only 6% perceived the white cross. Similarly, if the participant was attending to the white letters, they were more likely to notice the cross it was white (94%) than if it was light gray (75%), dark gray (56%), or black (0%).<ref>Most et al. (2001). How not to be seen: the contribution of similarity and selective ignoring to sustained inattentional blindness. Psychological Science, vol 1: 9-17</ref> This study demonstrates that the more similar an unexpected object is to the attended object, the more likely it is to be perceived, thus reducing the chance of inattentional blindness.
  +
  +
==Benefits of Inattentional Blindness==
  +
[[William James]] addressed the benefits of attention by saying, “Only those items which I notice shape my mind – without selective interest, experience is utter chaos”.<ref name="camc.ca">Canadian Aviation Maintenance Council. (2002). Inattentional Blindness: Let’s Not Blame The Victim Just Yet. 18(1), 23-29. Retrieved from http://www.camc.ca/fr/SMS_40/Articles_270/8.html</ref> Humans have a limited mental capacity that is incapable of attending to all the sights, sounds and other inputs that rush the senses every moment. Inattentional blindness is beneficial in the sense that it is a mechanism that has evolved with attention to help filter out irrelevant input, allowing only important information to reach consciousness.<ref name="camc.ca"/> Several researchers, notably [[James J. Gibson]], have argued that, even before the [[retina]], perception begins in the ecology, which has turned perceptual processes into informational relationships in the environment through [[evolution]].<ref name="pnas.org">Ohman, A. (2007). Has evolution primed humans to “beware the beast”? Proceedings of the National Sciences of the United States of America, 104(42). Retrieved from http://www.pnas.org/content/104/42/16396.full#xref-ref-2-1</ref> This allows humans to focus our limited mental resources more efficiently in our environment. For example, New et al. maintain that survival required monitoring animals, both human and non-human, to become part of the evolutionary adaptiveness of the human species. They found that when participants were shown an image with a rapidly altering scene where the scene change included an animate or inanimate object that the participants were significantly better at identifying humans and animals. New et al. argue that better performance in detecting animals and humans is not a factor of acquired expertise, rather it is an evolved survival mechanism in human perception.<ref name="pnas.org"/>
  +
  +
==Broader Implications==
  +
Although the bulk of inattentional blindness research has been conducted in laboratory studies, the phenomenon occurs in a variety of everyday contexts. Depending upon the context, the occurrence of inattentional blindness could range from embarrassing and/or humorous to potentially devastating.
  +
  +
===Inattentional Blindness and Safety===
  +
Several recent studies of explicit attention capture have found that when observers are focused on some other object or event, they often experience inattentional blindness.<ref>Simons, D. J. (2000). Attentional Capture and Inattentional Blindness. Trends in Cognitive Sciences, 4(4), 147-155. Retrieved from ftp://lsr-ftp.nei.nih.gov/lsr/ArchiveDB/p0000128.pdf</ref> This finding has potentially tragic implications for [[distracted driving]]. If a person’s attention is focused elsewhere while driving, carrying on a conversation or text messaging, for example, they could fail to notice salient and distinctive objects, such as a stop sign, which could lead to serious injury and possibly even death. There have also been heinous incidents attributed to inattentional blindness behind the wheel. For example, a Pennsylvania highway crew accidentally paved over a dead dear that was on the road. When questioned regarding their actions, the workers claimed to have never seen the dead deer.<ref>Simons, D. J., Clifford, E. R., Most, S. B., and Scholl B. J. What You See Is What You Set: Sustained Inattentional Blindness and the Capture of Awareness. American Psychological Association: Psychological Review, 112(1), 217-242. Retrieved from http://perception.research.yale.edu/papers/05-Most-EtAl-PsychRev.pdf</ref>
  +
  +
Many policies are being implemented around the world to decrease the competition for explicit attention capture while operating a vehicle. For example, there are legislative efforts in many countries aimed at banning or restricting the use of cell phones while driving. Research has shown that the use of both hands-free and hand-held cellular devices while driving results in the failure of attention to explicitly capture other salient and distinctive objects, leading to significantly delayed reaction times, as well as inattentional blindness.<ref>Horrey, W. J., & Wickens, C. D. (2006). Examining the Impact of Cell Phone Conversations on Driving Using Meta-Analytic Techniques. Human Factors: The Journal of the Human Factors and Ergonomics Society, 48(196), 196-205. Retrieved from http://dept.wofford.edu/neuroscience/NeuroSeminar/pdfFall2011/HorreyWickens2006_wk1_driving.pdf</ref> Alarmingly, a study published in 1997, based on accident data in [[Toronto]], found the risk involved in driving while using a cell phone to be similar to that of driving drunk. In both cases, the risk of a collision was three to six times higher compared to a sober driver not using a cell phone.<ref>Incantalupo, T. (2003, July 22). Driving Under Influence of a Phone. Newsday. Retrieved from http://www.newsday.com/news/driving-under-influence-of-a-phone-1.474713</ref> Moreover, Strayer et al. (2003) found that when controlling for driving difficulty and time on task, cell-phone drivers exhibited greater impairment than intoxicated drivers, using a high-fidelity [[driving simulator]].<ref>Strayer, D. L., Drews, F. A., & Crouch, D. J. (2003). Fatal Distraction? A Comparison of the Cell-Phone Driver and the Drunk Driver. University of Utah. Retrieved from http://www.psych.utah.edu/AppliedCognitionLab/DrivingAssessment2003.pdf</ref>
  +
  +
Inattentional blindness is also prevalent in aviation. The development of [[Heads-up display]] (HUD) for pilots, which project information onto the windshield or onto a helmet-mounted display, has enabled pilots to keep their eyes on the windshield, but simulator studies have found that HUD may cause runway incursion accidents, where one plane collides with another on the runway.<ref name="camc.ca"/> This finding is particularly concerning because HUDs are becoming more common in automobiles, which could lead to potential roadway incursions.<ref name="camc.ca"/> When a particular object or event captures attention to the extent to which the beholders’ attentional capacity is completely absorbed, the resulting inattentional blindness has been known to cause dramatic accidents. For example, an airliner crew, engrossed with a blinking console light, failed to notice the approaching ground and register hearing the danger alarm sounding before the airliner crashed.<ref name="camc.ca"/>
  +
  +
===Inattentional Blindness and Magic===
  +
Collaborative efforts to establish links between science and magic have examined the relationship of the processes underlying inattentional blindness and the concept of [[Misdirection (magic)|misdirection]]—a magician’s ability to manipulate attention in order to prevent his/her audience from seeing how a trick was performed. In several misdirection studies, including Kuhn and Tatler (2005),<ref>Kuhn, G., & Tatler B.W. (2005). Magic and fixation: Now you don't see it, now you do. Perception, 35(9), 1155-1161.</ref> participants watch a “vanishing item” magic trick. After the initial trial, participants are shown the trick until they detect the item dropping from the magician’s hand. Most participants see the item drop on the second trial. The critical analyses involved differences in eye movements between the detected and undetected trials. These repetition trials are similar to the full-attention trial in the inattentional blindness paradigm, as both involve the detection of the unexpected event and, by detecting the unexpected event on the second trial, demonstrate that the event is readily perceivable.<ref>Kuhn, G., & Tatler, B. W. (2010). Misdirected by the gap: The relationship between inattentional blindness and attentional misdirection. Consciousness and Cognition, doi:10.1016/j.concog.2010.09.013</ref>
  +
  +
The main difference between inattentional blindness and misdirection involves how attention is manipulated. While inattentional blindness tasks require an explicit distractor, the attentional distraction in misdirection occurs through the implicit yet systematic orchestration of attention.<ref name="Kuhn, G. 2010">Kuhn, G., & Tatler, B. W. Misdirected by the gap: The relationship between inattentional blindness and attentional misdirection. Consciousness and Cognition (2010), doi:10.1016/j.concog.2010.09.013</ref> Moreover, there are several varieties of misdirection and different types are likely to induce different cognitive and perceptual processes, which vary the misdirection paradigm’s resemblance to inattentional blindness.<ref name="Kuhn, G. 2010"/>
  +
  +
Although the aims of magic differ from those of neuroscience; magicians wish to exploit cognitive weaknesses, whereas neuroscientists seek to understand the brain and the neuronal significance of cognitive functions. Several researchers have argued that neuroscientists and psychologists can learn a lot from incorporating the real world experience and knowledge of magicians into their fields of research. The techniques developed over centuries of stage magic by magicians may also be utilized by neuroscience as powerful probes of human cognition.<ref>Martinez-Conde, S., & Macknik, S. L. (2008). Magic and the Brain. Scientific American, December 2008, 72-79. Retrieved from http://macknik.neuralcorrelate.com/pdf/articles/sciam08.pdf</ref>
  +
 
==See also==
 
* [[Attention]]
  +
* [[Attention disorders]]
  +
* [[Attentional Blink]]
  +
* [[Memory]]
  +
* [[Perception]]
  +
* [[Three-Card Monte]]
   
 
==References==
[[Category:Cognition]]
 
  +
<references />
[[Category:Attention]]
 
   
   
   
  +
[[Category:Attention disorders]]
{{Psych-stub}}
 
   
 
{{enWP|Inattentional blindness}}
 
{{enWP|Inattentional blindness}}

Latest revision as of 03:45, 21 January 2021

Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Individual differences | Personality | Philosophy | Social |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |

Cognitive Psychology: Attention · Decision making · Learning · Judgement · Memory · Motivation · Perception · Reasoning · Thinking  - Cognitive processes Cognition - Outline Index


Inattentional Blindness is the event in which an individual fails to recognize an unexpected stimulus that is in plain sight. The term inattentional blindness was coined by Arien Mack and Irvin Rock in 1992 and was used as the title of Mack and Rock's book published by MIT press in 1998. Here, they describe the discovery of Inattentional Blindness and include a collection of procedures used in exemplifying the phenomenon.[1] Research on inattentional blindness, also sometimes referred to as perceptual blindness, suggests that this phenomenon can occur in all individuals, independent of cognitive deficits. It is simply impossible for one to attend to all the visual stimuli in a visual field, and as a result, a temporary "blindness" effect can take place. That is, individuals fail to see objects or stimuli that are unexpected and quite often salient.

The following criteria are required to classify an event as an inattentional blindness episode: 1) the observer must fail to notice a visual object or event, 2) the object or event must be fully visible, 3) observers must be able to readily identify the object if they are consciously perceiving it,[1] and 4) the event must be unexpected and the failure to see the object or event must be due to the engagement of attention on other aspects of the visual scene and not due to aspects the visual stimulus itself.[1] Individuals who experience inattentional blindness are usually unaware of this effect, which can play a subsequent role on behavior.

Inattentional blindness is related to but distinct from other failures of visual awareness such as change blindness, repetition blindness, visual masking, and attentional blink. The key aspect of inattentional blindess which makes it distinct from other failures in awareness rests on the fact that the undetected stimulus is unexpected.[2] It is the unexpected nature of said stimulus that differentiates inattentional blindness from failures of awareness such as attentional failures like the aforementioned attentional blink. It is critical to acknowledge that occurrences of inattentional blindness are attributed to the failure to consciously attend to an item in the visual field as opposed the absence of cognitive processing.

Findings such as inattentional blindness - the failure to notice a fully visible but unexpected object because attention was engaged on another task, event, or object - has changed views on how the brain stores and integrates visual information, and has led to further questioning and investigation of the brain and importantly of cognitive processes.

The Cognition Debate - Early vs. Late Selection of Attention

One of the most foremost conflicts among researchers of inattentional blindness surrounds the processing of unattended stimuli. More specifically, there is disagreement in the literature about exactly how much processing of a visual scene is completed before selection dictates which stimuli will be consciously perceived, and which will not (i.e. Inattentional Blindness). There exists two basic schools of thought on the issue - those who believe selection is done early in the perceptual process, and those who believe it is done only after significant processing.[3] Early selection theorists propose that perception of stimuli is a limited process requiring selection to proceed. This suggests that the decision to attend to specific stimuli occurs early in processing, soon after the rudimentary study of physical features; only those selected stimuli are then fully processed. On the other hand, proponents of late selection theories argue that perception is an unlimited operation, and all stimuli in a visual scene are processed simultaneously. In this case, selection of relevant information is done after full processing of all stimuli.[4]

While early research on the topic was heavily focused on early selection, research since the late 1970s has shifted mainly to the late selection theories. This change resulted primarily from a shift in paradigms used to study inattentional blindness which revealed new aspects of the phenomenon.[5] Today, late selection theories are generally accepted, and continue to be the focus of the majority of research concerning inattentional blindness.

Evidence for Late Selection

A significant body of research has been gathered in support of late selection in the perception of visual stimuli.

One of the popular ways of investigating late selection is to assess the priming properties (i.e. influencing subsequent acts[6]) of unattended stimuli. Often used to demonstrate such effects is the stem completion task. While there exist a few variations, these studies generally consist of showing participants the first few letters of words, and asking them to complete the string of letters to form an English word.[6] It has been demonstrated that observers are significantly more likely to complete word fragments with the unattended stimuli presented in a trial than with another similar word.[7] This effect holds when stimuli are not words, but instead objects. When photos of objects are shown too quickly for participants to identify, subsequent presentation of those items lead to significantly faster identification in comparison to novel objects.[6]

An interesting study by Mack and Rock has also revealed that showing a word stimulus differing from the participant's name by one letter did not generally call conscious attention. By simply changing a character, transforming the presented word into the observer's first name, the now highly meaningful stimulus is significantly more likely to be attended to. This suggests that the stimuli are being extensively processed, at least enough to analyze their meaning. These results point to the fact that attentional selection may be determined late in processing.[7]

The evidence outlined above suggests that even when stimuli are not processed to the level of conscious attention, they are nonetheless perceptually and cognitively processed, and can indeed exert effects on subsequent behavior.[8]

Evidence for Early Selection

While the evidence supporting late selection hypotheses is significant and has been consistently reproduced, there also exists a body of research suggesting that unattended stimuli in fact may not receive significant processing.

For example, in an fMRI study by Rees and colleagues, brain activity was recorded while participants completed a perceptual task. Here they examined the neural processing of meaningful (words) and meaningless (consonant string) stimuli both when attended to, and when these same items were unattended. While no difference in activation patterns were found between the groups when the stimuli were unattended, differences in neural processing were observed for meaningful versus meaningless stimuli to which participants overtly attended. This pattern of results suggests that ignored stimuli are not processed to the level of meaning, i.e. less extensively than attended stimuli.[9] Participants do not seem to be detecting meaning in stimuli to which they are not consciously attending.

Theories of Inattentional Blindness

Perceptual Load

This particular hypothesis bridges the gap between the early and late selection theories. Authors integrate the viewpoint of early selection stating that perception is a limited process (i.e. cognitive resources are limited), and that of the late selection theories assuming perception as an automatic process.[4] This view proposes that the level of processing which occurs for any one stimulus is dependent on the current perceptual load. That is, if the current task is attentionally demanding and its processing exhausts all the available resources, little remains available to process other non-target stimuli in the visual field. Alternatively, if processing requires a small amount of attentional resources, perceptual load is low and attention is inescapably directed to the non-target stimuli.[3]

The effects of perceptual load on the occurrence of inattentional blindness is elegantly demonstrated in a study by Fougnie and Marois. Here, participants were asked to complete a memory task involving either the simple maintenance of verbal stimuli, or the rearrangement of this material, a more cognitively demanding exercise. While subjects were completing the assigned task, an unexpected visual stimulus was presented. Results revealed that unexpected stimuli were more likely to be missed during manipulation of information than in the more simple rehearsal task.[10]

In a similar type of study, fMRI recordings were done while subjects took part in either low-demand or high-demand subtraction tasks. While performing these exercises, novel visual distractors were presented. When task demands were low and used a smaller portion of the finite resources, distractors captured attention and sparked visual analysis as shown by brain activation in the primary visual cortex. These results, however, did not hold when perceptual load was high; in this condition, distractors were significantly less often attended to and processed.[3]

Thus, higher perceptual load, and therefore more significant use of attentional resources, appears to increase the likelihood of inattentional blindness episodes.

Inattentional Amnesia

The theory of inattentional amnesia provides an interesting alternative in the explanation of inattentional blindness. It suggests that this phenomenon does not stem from failures in capture of attention or in actual perception of stimuli, but instead from a failure in memory. The unnoticed stimuli in a visual scene are attended to and consciously perceived, but are rapidly forgotten rendering them impossible to report.[11] In essence, inattentional amnesia refers to the failure in creating a lasting explicit memory; by the time a subject is asked to recall seeing an item, their memory for the stimulus has vanished.[12]

While it is difficult to tease apart a failure in perception from one in memory, some research has attempted to shed light on the issue. In a classic study of inattentional blindness, a woman carrying an umbrella through a scene goes unnoticed. Despite stopping the video while she is walking through and immediately asking participants to identify which of two people they have seen - leaving as little delay as possible between presentation and report - observers very often fail to correctly identify the woman with the umbrella. No differences in performance were identified whether the video was stopped immediately after the unexpected event or moments later. These findings would seem to oppose the idea of inattentional amnesia, however advocates of the theory could always contend that the memory test simply came too late and that the memory had already been lost.[13]

Expectation

The very phenomenon of Inattentional blindness is defined by a lack of expectation for the unattended stimulus. Some researchers believe that it is not inattention that produces blindness, but in fact the aforementioned lack of expectation for the stimuli.[8] Proponents of this ideology often state that classic methods for testing inattentional blindness are not manipulating attention per se, but instead the expectation for the presentation of a visual item.[14]

Studies investigating the effect of expectation on episodes of inattentional blindness have shown that once observers are made aware of the importance of the to be presented stimuli, for example stating that one will later be tested on it, the phenomenon essentially disappears.[7] While admitting to possible ambiguities in methodology, Mack, one of the foremost researchers in the field, holds strongly that inattentional blindness stems predominantly from a failure of attentional capture. He points out that if expectation does not mediate instances of very closely linked phenomena such as attentional blink and change blindness (whereby participants have difficulty identifying the changing object even when they are explicitly told to look for it), it is unlikely that inattentional blindness can be explained solely by a lack of expectation for stimulus presentation.[8]

Classic Experiments Demonstrating Inattentional Blindness

Invisible Gorilla Test

The Invisible Gorilla Test is one of the most widely known experiments pertaining to inattentional blindness. It was done by Daniel Simmons from the University of Illinois at Urbana–Champaign and Christopher Chabris from Harvard University. Their study was a revised version of earlier studies conducted by Ulric Neisser and Becklen in 1975. It consists of asking participants to look at a video of two teams, one black and one white, with three people on each. The participants are asked to count how many times a basketball is passed between members of the white team. While this is happening, a person dressed in a gorilla costume walks and stands in front of the camera, thumps its chest, then walks off camera. It is on screen for about 9 seconds. After watching the video, the participants are asked if they noticed anything out of the ordinary, and about half of them were so focused on counting, also known as selective attention, that they did not notice other stimulus in their eyesight, the gorilla. There are also other versions of this experiment, in which a woman walks through the scene carrying an umbrella, or in which the participants are asked to only count either aerial passes or only bounce passes.[15] In a subsequent and similar study by Daniel Memmert, the gorilla video was used but in addition, the eye movements and fixations of the participants were recorded and analyzed. It was found that the participants who failed to perceive the gorilla still spent about 25 frames or a total of one second fixated on it.[16]

This classic study is a clear example of how people can fail to perceive a stimulus that is fully visible when their attention is focused on a different task, and as shown in the following example, inattentional blindness is applicable to real-life situations as well.

Perception and Inattentional Blindness-A Real-world Experiment

In 1995, Officer Kenny Conley was chasing a shooting suspect. An undercover officer was in the same vicinity and was mistakenly taken down by other officers while Conely ran by and failed to notice. A jury later convicted Officer Conley believing he had seen the fight, yet he stood by his word that he had, in fact, not seen it.

Christopher Chabirs, Adam Weinberger, Matthew Fontain and Daniel J. Simons took it upon themselves to see if this scenario was possible. They designed an experiment in which participants were asked to run about 30 feet behind Officer Conley himself, and count how times he touched his head. A fight was staged to appear about 8 meters off the path, and was visible for approximately 15 seconds. The procedure in its entirety lasted about 2 minutes and 45 seconds, and participants were then asked to report the number of times they had seen Officer Conley touch his head with either hand (medium load), both hands (high load), or were not instructed to count at all (low load). After the run, participants were asked 3 questions: 1) If they had noticed the fight; 2) if they had noticed a juggler, and 3) if they had noticed someone dribbling a basketball. Questions 2) and 3) were control questions, and no one falsely reported these as true.

Participants were significantly more likely to notice the fight when the experiment was done during the day as opposed to in the dark. Additionally, sightings of the fight were most likely to be reported in the low load condition (72%) than in either the medium load (56%), or high load conditions (42%).[17] These results exemplify a real world occurrence of inattentional blindness, and provide evidence that officer Conley could indeed have missed the fight because his attention was focused elsewhere. Moreover, these results add to the body of knowledge suggesting that as perceptual load increases, less resources remain to process items not explicitly focused on, and in turn episodes of inattentional blindness become more frequent.

Limitations of Perception or Memory?

Arien Mack and Irvin Rock’s findings on inattentional blindness is summarized in their 1988 book which comes to the generalized conclusion that no conscious perception can occur without attention.[7] Evidence through research on inattentional blindness contemplates that it may be possible that inattentional blindness reflects a problem with memory rather than with perception.[7] It is argued that at least some instances of inattentional blindness are better characterized as memory failures then perceptual failures. The extent to which unattended stimuli fail to engage perceptual processing is an empirical question that the combination of inattentional blindness and other various measures of processing can be used to address.[1]

The theory behind inattentional blindness research suggests that we consciously experience only those objects and events to which we directly attend.[7] That means that the vast majority of information in our field of vision goes unnoticed. Thus if we miss the target stimulus in an experiment, but are later told about the existence of the stimulus, this sufficient awareness allows participants to report and recall the stimulus now that attention has been allocated to it.[1] Mack and Rock, and their colleagues discovered a striking array of visual events to which people are inattentionally blind.[7] However the debate arises whether this inattentional blindness was due to memory or perceptual processing limitations.

Mack and Rock note that explanations for inattentional blindness can reflect a basic failure of perceptual processes to be engaged by unattended stimuli. Or that it may reflect a failure of memorial processes to encode information about unattended stimuli. It is important to note that the memory failure does not have to do with forgetting something that has been encoded by losing access to the memory of the stimulus from time of presentation to time of retrieval, rather that the failure is attributed to information not being encoded when the stimulus was present.[7] It seems that inattentional blindness can be explained by both memory and perceptual failures because in experimental research participants may fail to report what was on display due to failures in encoded information (memory) or a failure in perceptually processed information (perception).[7]

Neuropsychological analogies of Inattentional Blindness

There are similarities in the types of unconscious processing apparent in inattentional blindness and in neuropsychological syndromes such as visual neglect and extinction. The analogy between these phenomenon’s seems to generate more questions as well as answers. These answers are fundamental for our understanding of the relationship between attention, stimulus coding and behavior.

Visual neglect

Research has shown that some aspects of the syndrome of unilateral visual neglect appear to be similar to normal subjects in a state of inattentional blindness. In neglect, patients with lesions to the parietal cortex fail to respond to and report stimuli presented on the side of space contralateral to damage.

File:Parietal lobe animation small.gif

Animation. Parietal lobe (red) of left cerebral hemisphere.

[8][18] That is, they appear to be functionally blind to a range of stimuli. Since such lesions do not result in any sensory deficits, shortcomings have been explained in terms of a lack of attentional processing, for which the parietal cortex plays a large role.[19] These phenomena draw strong parallels to one another, as in both cases stimuli are perceptible but unreported when unattended.

Extinction

In the phenomenon of extinction, patients can report the presence of a single stimulus presented on the affected side, but then fail to detect it when a second stimulus is presented simultaneously on the 'good' (ipsilateral) side.[20] Here the stimulus on the affected side seems to lose under conditions of attentional competition from stimuli in the ipsilesional field.[20] The consequence of this competition is that the extinguished items may not be detected.

Similar to studies of inattentional blindness, there is evidence of processing taking place in the neglected field. For example, there can be semantic priming from a stimulus presented in the neglected field, which affects responses to stimuli subsequently presented on the unimpaired side.[21] Apparently in both neglect and inattentional blindness, there is some level processing of stimuli even when they are unattended.[21] However one major difference between neuropsychological symptoms such as neglect and extinction, and inattentional blindness concerns the role of expectation.[21] In inattentional blindness, subjects do not expect the unreported stimulus. In contrast, in neglect and extinction, patients may expect a stimulus to be presented on the affected side but still fail to report it when another it may be that expectation affects reportability but not the implicit processing of stimuli.[21]

Further explanations of the phenomenon of inattentional blindness include inattentional amnesia, inattentional agnosia and change blindness.

Inattentional Agnosia

An explanation for this phenomenon is that observers see the critical object in their visual field but fail to process it extensively enough to retain it . Individuals experience Inattentional Agnosia after having seen the target stimuli but not consciously being able to identify what the stimuli is. It is possible that observers are not even able to identify that the stimuli they are seeing are coherent objects.[22] Thus observers perceive some representation of the stimuli but are actually unaware of what that stimulus is. It is because the stimulus is not encoded as a specific thing, that it later is not remembered. Individuals fail to report what the stimuli is after it has been removed. However, despite a lack in ability to fully process the stimuli, experiments have shown a priming effect of the critical stimuli. This priming effect indicates that the stimuli must have been processed to some degree, this occurs even if observers are unable to report what the stimuli is.[23]

Change Blindness

Inattentional blindness is the failure to see a stimulus, such as an object that is present in a visual field. However, Change Blindness is the failure to notice something different about a visual display. Change blindness is directly related to memory, individuals who experience the effects of change blindness fail to notice something different about a visual display from one moment to the next.[2] In experiments that test for this phenomenon participants are shown an image that is then followed by another duplicate image that has had a single change made to it. Participants are asked to compare and contrast the two images and identify what the change is. In inattentional blindness experiments, participants fail to identify some stimulus in a single display, a phenomenon that doesn’t rely on memory the way change blindness does.[2] Inattentional blindness refers to an inability to identify an object all together where as change blindness is a failure to compare a new image or display to one that was previously stored in memory.[2]

Additional Factors Exhibiting Effects on Inattentional Blindness

Age and Expertise

In 2006, Daniel Memmert conducted a series of studies in which he tested the how age and expertise of participants affect inattentional blindness. Using the gorilla video, he tested 6 different groups of participants. There were 2 groups of children (average age=7) half with no experience in basketball, and the other half with 2 years experience; 2 groups of juniors (average age=13) half with no experience in basketball, and the other half with 5 years of experience; and 2 groups of adults (average age = 24) half with no experience in basketball, the other half with over 12 years of experience. He then instructed all the groups to keep track of how many passes the people on the black team made.

Overall, the children with or without any basketball experience failed to perceive the gorilla more than the juniors or the adults. There were no significant difference between the inexperienced junior and adult groups, or between the experienced junior and adult groups.[16] This pattern of results suggests that until the approximate age of 13, presumably because certain aspects of cognition are still under development, inattentional blindness occurrences are more frequent, but become consistent throughout the remainder of the life span.

Additionally, the juniors with basketball experience noticed the gorilla significantly more than the juniors with no basketball experience; and the group of experienced adults noticed the gorilla significantly more than the non-experienced adults. This suggests that if one has had much experience with the stimuli in a visual field, they are more likely to consciously perceive the unexpected object.

Similarity Between Stimuli

A series of studies conducted to test how similarity can influence the perception of a present stimulus. In the study, they asked participants to fixate on a central point on a computer screen and count how many times either white or black letters bounced off the edges of the screen. The first 2 trials did not contain an unexpected event, but the third trial was the critical trial in which a cross that had the same dimensions as the letters and varied in colour (white/light gray/dark gray/black) moved from the right side of the screen to the left side and passed through the central point. The results revealed the following: during the critical event, the more similar the colour of the cross was to the colour of the attended letters, the more likely the participants were to perceive it, and the less similar the colour of the cross was to the attended colour decreased the likelihood of the cross being noticed. For the participants attending to the black letters, 94% perceived the black cross; 44% perceived the dark gray cross; 12% perceived the light gray cross, and only 6% perceived the white cross. Similarly, if the participant was attending to the white letters, they were more likely to notice the cross it was white (94%) than if it was light gray (75%), dark gray (56%), or black (0%).[24] This study demonstrates that the more similar an unexpected object is to the attended object, the more likely it is to be perceived, thus reducing the chance of inattentional blindness.

Benefits of Inattentional Blindness

William James addressed the benefits of attention by saying, “Only those items which I notice shape my mind – without selective interest, experience is utter chaos”.[25] Humans have a limited mental capacity that is incapable of attending to all the sights, sounds and other inputs that rush the senses every moment. Inattentional blindness is beneficial in the sense that it is a mechanism that has evolved with attention to help filter out irrelevant input, allowing only important information to reach consciousness.[25] Several researchers, notably James J. Gibson, have argued that, even before the retina, perception begins in the ecology, which has turned perceptual processes into informational relationships in the environment through evolution.[26] This allows humans to focus our limited mental resources more efficiently in our environment. For example, New et al. maintain that survival required monitoring animals, both human and non-human, to become part of the evolutionary adaptiveness of the human species. They found that when participants were shown an image with a rapidly altering scene where the scene change included an animate or inanimate object that the participants were significantly better at identifying humans and animals. New et al. argue that better performance in detecting animals and humans is not a factor of acquired expertise, rather it is an evolved survival mechanism in human perception.[26]

Broader Implications

Although the bulk of inattentional blindness research has been conducted in laboratory studies, the phenomenon occurs in a variety of everyday contexts. Depending upon the context, the occurrence of inattentional blindness could range from embarrassing and/or humorous to potentially devastating.

Inattentional Blindness and Safety

Several recent studies of explicit attention capture have found that when observers are focused on some other object or event, they often experience inattentional blindness.[27] This finding has potentially tragic implications for distracted driving. If a person’s attention is focused elsewhere while driving, carrying on a conversation or text messaging, for example, they could fail to notice salient and distinctive objects, such as a stop sign, which could lead to serious injury and possibly even death. There have also been heinous incidents attributed to inattentional blindness behind the wheel. For example, a Pennsylvania highway crew accidentally paved over a dead dear that was on the road. When questioned regarding their actions, the workers claimed to have never seen the dead deer.[28]

Many policies are being implemented around the world to decrease the competition for explicit attention capture while operating a vehicle. For example, there are legislative efforts in many countries aimed at banning or restricting the use of cell phones while driving. Research has shown that the use of both hands-free and hand-held cellular devices while driving results in the failure of attention to explicitly capture other salient and distinctive objects, leading to significantly delayed reaction times, as well as inattentional blindness.[29] Alarmingly, a study published in 1997, based on accident data in Toronto, found the risk involved in driving while using a cell phone to be similar to that of driving drunk. In both cases, the risk of a collision was three to six times higher compared to a sober driver not using a cell phone.[30] Moreover, Strayer et al. (2003) found that when controlling for driving difficulty and time on task, cell-phone drivers exhibited greater impairment than intoxicated drivers, using a high-fidelity driving simulator.[31]

Inattentional blindness is also prevalent in aviation. The development of Heads-up display (HUD) for pilots, which project information onto the windshield or onto a helmet-mounted display, has enabled pilots to keep their eyes on the windshield, but simulator studies have found that HUD may cause runway incursion accidents, where one plane collides with another on the runway.[25] This finding is particularly concerning because HUDs are becoming more common in automobiles, which could lead to potential roadway incursions.[25] When a particular object or event captures attention to the extent to which the beholders’ attentional capacity is completely absorbed, the resulting inattentional blindness has been known to cause dramatic accidents. For example, an airliner crew, engrossed with a blinking console light, failed to notice the approaching ground and register hearing the danger alarm sounding before the airliner crashed.[25]

Inattentional Blindness and Magic

Collaborative efforts to establish links between science and magic have examined the relationship of the processes underlying inattentional blindness and the concept of misdirection—a magician’s ability to manipulate attention in order to prevent his/her audience from seeing how a trick was performed. In several misdirection studies, including Kuhn and Tatler (2005),[32] participants watch a “vanishing item” magic trick. After the initial trial, participants are shown the trick until they detect the item dropping from the magician’s hand. Most participants see the item drop on the second trial. The critical analyses involved differences in eye movements between the detected and undetected trials. These repetition trials are similar to the full-attention trial in the inattentional blindness paradigm, as both involve the detection of the unexpected event and, by detecting the unexpected event on the second trial, demonstrate that the event is readily perceivable.[33]

The main difference between inattentional blindness and misdirection involves how attention is manipulated. While inattentional blindness tasks require an explicit distractor, the attentional distraction in misdirection occurs through the implicit yet systematic orchestration of attention.[34] Moreover, there are several varieties of misdirection and different types are likely to induce different cognitive and perceptual processes, which vary the misdirection paradigm’s resemblance to inattentional blindness.[34]

Although the aims of magic differ from those of neuroscience; magicians wish to exploit cognitive weaknesses, whereas neuroscientists seek to understand the brain and the neuronal significance of cognitive functions. Several researchers have argued that neuroscientists and psychologists can learn a lot from incorporating the real world experience and knowledge of magicians into their fields of research. The techniques developed over centuries of stage magic by magicians may also be utilized by neuroscience as powerful probes of human cognition.[35]

See also

References

  1. 1.0 1.1 1.2 1.3 1.4 Rock, I., Linnet, C. M., Grant P.I., & Mack, A. (1992). Perception without attention: Results of a new method. Cognitive Psychology, 24, 502-534.
  2. 2.0 2.1 2.2 2.3 Driver, J. (1998). The neuropsychology of spatial attention. In H. Pashler (Ed.), Attention. (pp. 297-340). London: Taylor Francis
  3. 3.0 3.1 3.2 Spinks. J.A., Zhang, J.X., Fox, P.T., Gao, J-H., & Tan, L.H. (2004). More workload on the central executive of working memory, less attention capture by novel visual distractors: evidence from an fMRI study. NeuroImage, 23, 517-524
  4. 4.0 4.1 Lavie, N., & Tsal, Y. (1994). Perceptual load as a major determinant of the locus of selection in visual attention. Perception & Psychophysics, 56(2), 183-197
  5. Kahneman, D., & Treisman, A. (1984). Changing views of attention and automacity. In R. Parasuraman & D.R Davies (Eds.), Varieties of Attention (pp. 29-61). New York: Academic Press
  6. 6.0 6.1 6.2 Mack, A. (2003). Inattentional blindness: Looking without seeing. Current Directions in Psychological Science, 12(5), 180-184.
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 Mack, A. and Rock, I. (1998). Inattentional Blindness, MIT Press
  8. 8.0 8.1 8.2 8.3 Mack, A. (2001). Inattentional blindness: Reply to commentaries. Psyche, 7(16), 1-7.
  9. Rees, G., Russell, C., Firth, C., & Driver, J. (1999). Inattentional blindness versus inattentional amnesia. Science, 286, 849-860.
  10. Fougnie, D., & Marois, R. (2007). Executive working memory load induces inattentional blindness. Psychonomic Bulletin & Review, 14(1), 142-147.
  11. Simons, D.J. (2000). Attentional capture and inattentional blindness. Trends in Cognitive Science, 4(4), 147-155.
  12. Wolfe, J.M. (1999). Inattentional amnesia. In V. Coltheart (Ed.), Fleeting Memories (pp.71-94). Cambridge, MA: MIT Press.
  13. Becklen, R., & Cervone, D. (1983). Selective looking and the noticing of unexpected events. Memory & Cognition, 11(6), 601-608.
  14. Braun, J. (2001). Its great but not necessarily about attention. Psyche, 7(6), 1-7.
  15. Chabris, C. Clifford, E. Jimenez, R. Most, S. Scholl, B. Simons, D. (2001) "How Not to be Seen: The Contribution of Similarity and Selective Ignoring to Sustained Inattentional Bindness." Psychological Science. Vol 12 No. 1.
  16. 16.0 16.1 Memmert, D. (2006). The effects of eye movement, age, and expertise on inattentional blindness. Consciousness and cognition, vol 15, 620-627.
  17. Chabris, C. Fontaine, M. Simmons, D. Weinberger, A. (2011) “You do Not Talk About Fight Club if You Do Not Notice Fight Club: Inattentional Blindness For A Stimulated Real-World Assult.” i-Perception. 2: 150-153
  18. Moore, C. M., & Egeth, H. (1997). Perception without attention: Evidence of grouping under conditions of inattention. Journal of Experimental Psychology: Human Perception and Performance, 23, 339-352.
  19. Rafal, R. (1998). Neglect. In R. Parasuraman (Ed.), The Attentive Brain (pp.489-526). Cambridge. MA: MIT Press.
  20. 20.0 20.1 Humphreys, G.W., Romani, C., Olson, A., Riddoch, M.J. & Duncan, J. (1994). Non- spatial extinction following lesions of the parietal lobe in humans. Nature, 372, 357-359.
  21. 21.0 21.1 21.2 21.3 Mack, A., Tang, B., Tuma, R., & Rock, I. (1992). Perceptual organization and attention. Cognitive Psychology, 24, 475-501.
  22. Neisser, U. (1967). Cognitive psychology. New York: Appleton-Century-Crofts.
  23. Yantis, S. (1999). Seeing is attending. Contemporary Psychology, 44, 314-316.
  24. Most et al. (2001). How not to be seen: the contribution of similarity and selective ignoring to sustained inattentional blindness. Psychological Science, vol 1: 9-17
  25. 25.0 25.1 25.2 25.3 25.4 Canadian Aviation Maintenance Council. (2002). Inattentional Blindness: Let’s Not Blame The Victim Just Yet. 18(1), 23-29. Retrieved from http://www.camc.ca/fr/SMS_40/Articles_270/8.html
  26. 26.0 26.1 Ohman, A. (2007). Has evolution primed humans to “beware the beast”? Proceedings of the National Sciences of the United States of America, 104(42). Retrieved from http://www.pnas.org/content/104/42/16396.full#xref-ref-2-1
  27. Simons, D. J. (2000). Attentional Capture and Inattentional Blindness. Trends in Cognitive Sciences, 4(4), 147-155. Retrieved from ftp://lsr-ftp.nei.nih.gov/lsr/ArchiveDB/p0000128.pdf
  28. Simons, D. J., Clifford, E. R., Most, S. B., and Scholl B. J. What You See Is What You Set: Sustained Inattentional Blindness and the Capture of Awareness. American Psychological Association: Psychological Review, 112(1), 217-242. Retrieved from http://perception.research.yale.edu/papers/05-Most-EtAl-PsychRev.pdf
  29. Horrey, W. J., & Wickens, C. D. (2006). Examining the Impact of Cell Phone Conversations on Driving Using Meta-Analytic Techniques. Human Factors: The Journal of the Human Factors and Ergonomics Society, 48(196), 196-205. Retrieved from http://dept.wofford.edu/neuroscience/NeuroSeminar/pdfFall2011/HorreyWickens2006_wk1_driving.pdf
  30. Incantalupo, T. (2003, July 22). Driving Under Influence of a Phone. Newsday. Retrieved from http://www.newsday.com/news/driving-under-influence-of-a-phone-1.474713
  31. Strayer, D. L., Drews, F. A., & Crouch, D. J. (2003). Fatal Distraction? A Comparison of the Cell-Phone Driver and the Drunk Driver. University of Utah. Retrieved from http://www.psych.utah.edu/AppliedCognitionLab/DrivingAssessment2003.pdf
  32. Kuhn, G., & Tatler B.W. (2005). Magic and fixation: Now you don't see it, now you do. Perception, 35(9), 1155-1161.
  33. Kuhn, G., & Tatler, B. W. (2010). Misdirected by the gap: The relationship between inattentional blindness and attentional misdirection. Consciousness and Cognition, doi:10.1016/j.concog.2010.09.013
  34. 34.0 34.1 Kuhn, G., & Tatler, B. W. Misdirected by the gap: The relationship between inattentional blindness and attentional misdirection. Consciousness and Cognition (2010), doi:10.1016/j.concog.2010.09.013
  35. Martinez-Conde, S., & Macknik, S. L. (2008). Magic and the Brain. Scientific American, December 2008, 72-79. Retrieved from http://macknik.neuralcorrelate.com/pdf/articles/sciam08.pdf
This page uses Creative Commons Licensed content from Wikipedia (view authors).