Location as a feature in pigeons' recognition of visual objects.

A number of different phenomena in pigeon visual cognition suggest that pigeons do not immediately recognize two identical objects in different locations as being "the same." To examine this question directly, pigeons were trained in an absolute go/no-go discrimination between arbitrary selections from sets of 16 images of paintings by Claude Monet. Of the eight positive stimuli, four always appeared in the same location, whereas the other four appeared equally often in each of two locations; the same was true of the negative stimuli.

Feature- versus rule-based generalization in rats, pigeons and humans.

Humans can spontaneously create rules that allow them to efficiently generalize what they have learned to novel situations. An enduring question is whether rule-based generalization is uniquely human or whether other animals can also abstract rules and apply them to novel situations. In recent years, there have been a number of high-profile claims that animals such as rats can learn rules.

Pigeons use low rather than high spatial frequency information to make visual category discriminations.

Pigeons were trained to discriminate photographs of cat faces from dog faces. They were then presented with test stimuli involving high- and low-pass spatial frequency filtering. Discrimination was maintained with both types of filtered stimuli, though it was increasingly impaired the more information was filtered out, and high-pass filtering impaired discrimination more than low-pass filtering.