CONTROL OF PIGEONS SPATIAL SEARCH BY GRAPHIC LANDMARKS IN A TOUCH-SCREEN TASK

Pigeons learned to peck an unmarked 2-cm2 target area, defined by 4 visually distinct graphic landmarks, on a color monitor with an attached touch frame. The configuration of landmarks and target area was constant during training, but their location on the screen varied across trials. The presence, relative location, and features of the landmarks were manipulated on probe trials. Most birds showed control by only 1 or 2 of the landmarks, and some birds displayed surprisingly accurate search with a single landmark. For individual birds, landmark-removal tests were very consistent with landmark-shift tests in indicating which landmark or landmarks controlled search. However, the dominant landmark varied across birds. Manipulation of landmark color and shape revealed that control was based exclusively on color.