Abstract
Four pigeons discriminated whether a target spot appeared on a colored figural shape or on a differently colored background by first pecking the target and then reporting its location: on the figure or the background. We recorded three dependent variables: target detection time, choice response time, and choice accuracy. In a previous study, we found that pigeons were faster to detect the target, to report its location, and to learn the correct response on figure trials than on background trials; we also found that the pigeons were not using local display properties to perform the figure-background discrimination (Lazareva et al., in press). Here, we investigated the effects of changes in size and in display pre-exposure. Pigeons' accuracy on both figure and background trials increased as the size of the figure decreased. Both target detection time and choice reaction time were faster on figure trials than on background trials: this figural advantage increased as the size of the figure decreased. When the display containing the figure and background was shown 1, 2, or 4 s before onset of the target, target detection times were faster on both figure and background trials compared to the simultaneous presentation of the display and the target; as well, the disparity between figure and background trials increased with longer pre-exposure. A similar, but less pronounced, trend was found for choice reaction time. These results suggest that figure-ground segregation in people and pigeons is similarly affected by both geometrical and temporal variables.
This research was supported by National Institute of Mental Health Grant MH47313.