THE USE OF PIGMENTATION AND SHADING INFORMATION IN RECOGNIZING THE SEX AND IDENTITIES OF FACES

An investigation of what can be learned about representational process es in face recognition from the independent and combined effects of in verting and negating facial images is reported. In experiment 1, indep endent effects of inversion and negation were observed in a task of id entifying famous faces. In experiments 2 through 4 the question of whe ther effects of negation were still obtained when effects due to the r eversal of pigmentation in negative images were eliminated was examine d. By the use of images of the 3-D surfaces of faces measured by laser , and displays as smooth surfaces devoid of pigmentation, only effects of inversion were obtained reliably, suggesting that the effects obse rved in experiment 1 arose largely through the inversion of pigmentati on values in normal images of faces. The results of experiment 5 sugge sted that the difference was not due to the different task demands of experiments 2-4 compared with those of experiment 1. When normally pig mented face images were used in a task making similar demands to that of experiment 4, independent effects of inversion and negation were ag ain observed. When a task of sex classification was used in experiment s 6 and 7, clear effects of negation as well as inversion were observe d on latencies, though not accuracies, of responding. The results are interpreted in terms of the information content of pigmentation relati ve to shape from shading in different face-classification tasks. The r esults also reinforce other recent evidence demonstrating the importan ce of image intensity as well as spatial layout of face 'features'.