Scene gist categorization in pigeons

Abstract

Scene gist categorization in humans is rapid and accurate and appears to be tuned to fundamental statistical regularities in the visual world. Although pigeons have been reported to form many types of categorical judgments, little research has examined scene categorization by pigeons or the underlying mechanisms of it. The present study trained eight pigeons on a scene gist categorization task using a go/no-go procedure. Four birds were trained to discriminate between two natural categories (beach vs. mountain) and four were trained to discriminate between a natural (beach) and a man-made (street) category. The birds successfully learned both categorization tasks at a similar rate and to a high degree of accuracy (>80%). During a subsequent generalization test with novel images, strong transfer of discrimination was observed with only a modest generalization decrement. Finally, the birds were trained with progressively shorter stimulus durations (beginning with the original 5-sec duration and decreasing to less than 1 sec) to determine if they could still form a discrimination with limited visual information as with humans. Decreasing durations initially negatively affected performance, but over time the pigeons recovered and formed discriminations with stimulus presentations in the 200-500 ms range. The results indicate that, like humans, pigeons can form rapid scene gist categorization judgments. However, the visual information critical for these judgments remains to be determined