Elemental versus configural perception in a people-present/people-absent discrimination task by pigeons

In the present experiment, we investigated whether pigeons rely exclusively on elemental information or whether they are also able to exploit configural information in a people-present/people-absent discrimination task. Six pigeons were trained in a go/no-go procedure to discriminate between 800 color photographs characterized by the presence or absence of people. The people-present stimuli were designated as positive, and the people-absent stimuli were designated as negative. After training and a subsequent generalization test, the pigeons were presented with both familiar and novel people-present stimuli containing human figures that were distorted in one of seven different ways. All the pigeons learned the initial discrimination and also showed generalization to novel stimuli. In the subsequent test, performance on all types of distorted stimuli was diminished in comparison with that on the intact original pictures from which they had been derived. At the same time, however, peck rates clearly exceeded the level of responding found for regular people-absent stimuli. This result strongly suggests that responding was controlled by both the constituting target components and their spatial relations and, therefore, points to the dual importance of elemental and configural information.