Pigeons’ Performances of a Radial-Arm-Maze Analog Task: Effect of Spatial Distinctiveness

Abstract

Pigeons were presented with a radial-arm-maze analog task involving five response keys in one of four spatial arrangements. Two of the arrangements involved two-dimensional key displays that differed in degree of spatial separation (large display, Group L, vs. small display, Group S). The other two arrangements involved one-dimensional key displays in either a vertical (Group V) or a horizontal (Group H) array. Acquisition was faster for Groups L and S than for Groups V and H, however, the spatial separation for Group L did not further facilitate performance relative to Group S. Groups H and V performed poorly on this task. When delays were interpolated at different points in the trial, Group L made fewer errors when interrupted early and late in the trial, than when interrupted in the middle of the trial. This result suggests that pigeons in Group L used retrospective coding for choices made early in the trial and prospective coding for choices yet to be made late in the trial. Groups H and V showed flat, point-of-delay-interpolation error functions, a finding consistent with their poor overall performance. Half the birds in Group S performed similarly to Group L birds; the other half performed similarly to birds in Groups H and V.