Perceptual learning in pigeons: Decreased ability to discriminate samples mapped onto the same comparison in many-to-one matching

Abstract

Humans often treat two stimuli that are associated with a common response as similar in other contexts. They do so presumably because those stimuli become conceptually or perceptually more similar to each other (perceptual learning). An analogous phenomenon may occur in pigeons when they are trained with a matching-to-sample procedure in which more than one sample is mapped onto the same comparison. In the present research, pigeons were trained to select one comparison following either of two samples (S1 or S2) and to select the other comparison following either of two different samples (S3 or S4). When the samples were then presented as positive and negative stimuli in a simple successive discrimination, samples that had been associated with the same comparison during original training (e.g., S1 vs. S2) were more difficult to discriminate than were samples that had been associated with different comparisons (e.g., S1 vs. S3). Thus, it appears that perceptual learning occurs in pigeons as well.