Typicality effects in face and object perception: further evidence for the attractor field model

In a previous study, it was shown that a 50/50 morph of a typical and an atypical parent face was perceived to be more similar to the atypical parent face than to the typical parent face (Tanaka, Giles, Kremen, & Simon, 1998). Experiments 1 and 2 examine face typicality effects in a same/different discrimination task in which typical or atypical faces and their 80%, 70%, 60%, and 50% morphs were presented sequentially (Experiment 1) or simultaneously (Experiment 2). The main finding was that in both modes of presentation, atypical morphs were more poorly discriminated than their corresponding typical morphs. In Experiment 3, typicality effects were extended to the perception of nonface objects; in this instance, it was found that 50/50 morphs of birds and cars were judged to be more similar to their atypical parents than to their typical parents. These results are consistent with an attractor field model, in which it is proposed that the perception of a face or object stimulus depends not only on its fit to an underlying representation, but also on the representation's location in the similarity space.