Averaging temporal duration and spatial position.

Pigeons and humans performed on a task in which spatial position and elapsed time redundantly signaled the availability of reward. On each training trial, a landmark moved steadily across a monitor screen. After a fixed amount of time and movement, reward was available for a response. On occasional unrewarded tests, the landmark moved at 0.50, 0.75, 1.00, 1.50, or 2.00 times the training speed. In both pigeons and humans, the central tendency in the response distribution on tests differed across speeds, when measured in terms of both elapsed time and landmark position. Pigeons and humans seem to average a duration of time and a spatial position to find a single criterion time-place corresponding to the expected time-place of reward.