Control of pigeons' spatial search by graphic landmarks in a touch-screen task.

Abstract

Pigeons learned to peck an unmarked 2-cm 2 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.

Integration of spatial maps in pigeons

“…Pigeons have been shown to acquire separate landmark-goal vectors independently even in situations involving multiple landmarks (Spetch and Mondloch 1993;Spetch et al 1996Spetch et al ,1997. For example, after learning to find a hidden food goal in the presence of an array of landmarks, search locations on probe tests involving transformations of the landmark array (e.g., expansions of landmark locations or removal of individual landmarks) indicate that pigeons had encoded the vector between one or more individual landmarks and the goal.…”

Bayesian integration of spatial information.

“…Measurements of a digital copy of the graph show that over four tests, the peak location shifted on average 68% of the distance of the landmark shift, indicative of an average Figure 3. Data from 1 pigeon in a study by Spetch and Mondloch (1993, Figure 4). The bird was presented with an array of graphic landmarks, indicated by the variously shaped symbols (top panel).…”

“…The actual weight assigned to the preferred landmark can be estimated from landmark-shift tests, in which the preferred landmark was shifted with respect to the other three (Figure 8 of Spetch & Mondloch, 1993). Measurements of a digital copy of the graph show that over four tests, the peak location shifted on average 68% of the distance of the landmark shift, indicative of an average Figure 3.…”

“…In one study using the touch screen, results of single-cue tests and landmark-displacement tests were both published (Spetch & Mondloch, 1993). Pigeons had to search in the middle of four distinct graphic landmarks, placed irregularly around the goal at a short distance (Figure 3).…”

“…Performance was excellent with the preferred landmark and poor with other landmarks. The weight that should be assigned to the preferred landmark by Bayesian principles can be estimated from Table 1 of Spetch and Mondloch (1993), which lists the proportion of all pecks that fell within a small area around the goal on unrewarded tests with each single landmark. We divided the proportion of search at the target with the preferred landmark alone by the total of proportion search at the target with each of the four landmarks alone (summing across performance on four tests).…”