Abstract
The question whether judgements of facial expression show the typical pattern of categorical perception was examined using three sets of 11 photographs, each constituting an 11-step continuum extending between two extreme protypical exemplars: angry-sad, happy-sad and angry-afraid, respectively. For each continuum, intermediate exemplars were created using a morphing procedure. Subjects first identified all faces in each continuum in terms of the extreme expressions, and then performed an ABX discrimination task on pairs of faces two steps (Experiments 1 and 2) or three steps (Experiment 3) apart. The classical categorical perception prediction that discrimination performance must peak around the point on the continuum at which identification reaches 50% was tested not on group means, as in earlier studies, but on a subject-by-subject basis. It was supported by the results for both adults (Experiment 1) and 9- to 10-year-children (Experiment 3). For adults, two noncategorical interpretations of the main finding were discarded by showing that it was not replicated with the same material presented upside down (Experiment 2).