The lateral surface of the parietal lobe is cleft by a well-marked furrow, the intraparietal sulcus (IPS) of Turner, which consists of an oblique and a horizontal portion.
The IPS is involved in processing symbolic numerical information. A 2006 study by Jessica Cantlon et. al. concluded The IPS provides the neurobiological platform for nonsymbolic numerical processing in young children, then supports the expanding capacity for higher-math operations in adulthood.
The IPS is also involved in processing the Interprets the intent of others. A 2006 study by Scott Grafton and Antonia Hamilton has found that the IPS was strongly activated when the subject saw another person reach for an object that they want, like a cookie. "We were able to find the part of the brain involved in
interpreting the goal of another person, even if no words are
spoken," says Hamilton. 
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