THE ROLE OF SURFACE INFORMATION IN OBJECT RECOGNITION - STUDIES OF A VISUAL FORM AGNOSIC AND NORMAL SUBJECTS

Three experiments were conducted to explore the role of colour and oth er surface properties in object recognition. The effects of manipulati ng the availability of surface-based information on object naming in a patient with visual form agnosia and in two age-matched control subje cts were examined in experiment 1. The objects were presented under se ven different viewing conditions ranging from a full view of the actua l objects to line drawings of those same objects. The presence of colo ur and other surface properties aided the recognition of natural objec ts such as fruits and vegetables in both the patient and the control s ubjects. Experiment 2 was focused on four of the critical viewing cond itions used in experiment 1 but with a large sample of normal subjects . As in experiment 1, it was found that surface properties, particular ly colour, aided the naming of natural objects. The presence of colour did not facilitate the naming of manufactured objects. Experiment 3 w as focused on possible ways by which colour could assist in the recogn ition of natural objects and it was found that object naming was facil itated only if the objects were presented in their usual colour. The r esults of the experiments show that colour does improve recognition fo r some types of objects and that the improvement occurs at a high leve l of visual analysis.