The Thatcher illusion and face processing in infancy.

Adults readily detect changes in face patterns brought about by the inversion of eyes and mouth when the faces are viewed upright but not when they are viewed upside down. Research suggests that this illusion (the Thatcher illusion) is caused by the interfering effects of face inversion on the processing of second-order relational information (fine spatial information such as the distance between the eyes). In the current study, 6-month-olds discriminated 'thatcherized' faces when they were viewed upright but not when they were viewed upside down. These results are consistent with the notion that 6-month-olds are sensitive to second-order relational information while processing faces.