There are many comments and jokes on how people of one race look the same. Though the statement is over generalized it has an element of truth as it is a fact that individuals have a difficult time in telling people apart of a different race as compared to doing the same within their personal race. This observable fact is termed the other race effect and was first described about a hundred years ago. Since then there has been many studies in this phenomenon but researchers still haven’t fully understood why exactly does this occur; why is it so hard to differentiate between two people of a race. Recently, two pscychologists from Europe have published a document in PNAS that sheds some light on this, providing a neurophysiological basis for other race effect.
They did a study on 24 subjects, half of which were Western Caucasian, and the other being of East Asian heritage. Each participant was shown a succession of two faces displayed on a screen. Every pair had either faces of the one person or two unlike people, or one individuals face repeated in the series. Also, the expression would vary between the faces to make it a little harder to identify the same faces. The testers had to determine if the two faces are of the same individual or not.
In order to understand how the experiments worked, you should know that when a certain stimulus, as in this case the face, is shown two times to a person, his or hers neural activity related to the response decreases in the second instance, this mechanism is called the repetition suppression. In the brain, an electrophysiological signal, N170, is triggered when a human face comes into sight.
The repetition suppression works like this; when a second face is identified as being the same as the first by the brain, an N170 signal is decreased, but if the face is recognized as being different, the N170 should stay the same. What the researchers did was subtract the speed at which the signal was triggered by face number two from that which was triggered from the first so that they can ascertain the difference between the two stimuli. This measurement is the single-trial repetition suppression (stRS) value.
The common stRS value for these trials were the same for both and highest when subjected were shown a face of their race again. However, there was no distinct change in the values when an Asian saw a Caucasian face and vice versa; in fact they were almost the same as when a face of the same race was looked at. Hence, these results are first to suggest a neurophysiological basis for the other race effect.