Fig. 1.

Stimuli and conditions used in the experiment.A, Subset of target images. Monkeys were trained to pull one of two levers whenever they noticed any 1 of 70 target objects on the computer monitor set before them. Lever mappings (left or right) were arbitrarily assigned, but specific exemplars from the same basic-level category (e.g., playing cards or parrots) were mapped to the same lever. B, Two basic conditions were used. In the isolated condition (left), the target stimulus was presented alone in the center of the screen, against a gray background. In the embedded condition (right), the target was blended into 1 of 100 real world scenes.