Why do people so often have trouble telling those of a different race apart?

Now psychologists have identified the brain mechanism responsible for this other-race effect. Previous studies have identified the brain region responsible for the phenomenon, but the mechanisms underlying it have been unclear. So researchers showed 24 Caucasian and East Asian volunteers pairs of photos, one after the other. The pictures were either of two different people of the same racial group – either Caucasian or East Asian – or the same person with different facial expressions. At the same time they recorded the volunteers' brain activity using electroencephalography (EEG), which measures electrical activity produced by the firing of neurons in the brain. Normally, showing someone the same face twice generates a similar EEG pattern each time, although the activity levels is lower the second time. Different faces spark different activity patterns. When the volunteers were shown faces of people of a different race to their own, their neurons responded as if they were the same person, whether they were or not. The results were the same whether Caucasian volunteers were looking at East Asian faces or vice versa.