Delay of reinforcement switches attention between elements of a compound stimulus in humans, Reynolds (1961) revisited

One experiment in instrumental conditioning studied the effect of delayed reinforcement on attention, considered as the stimulus control produced by each element of a compound sample stimulus (CSS). A two-element (shape and color) CSS indicated the response to be reinforced between three comparison stimuli in an online matching-to-sample task with human participants. Forty-eight university students were assigned to three groups with different reinforcement delays: 0 s, 8 s, and 16 s (D0, D8, and D16). After learning the task, a separate test took place, with the elements of the CSS presented separately. Group D0 responded more to the shape. The D8 group responded to both elements, while the D16 group responded more to the color. Results showed that attention to each element of the CSS changes as reinforcement delay increases. These findings are similar to those of Urcelay and Miller (2009) on Pavlovian conditioning, pointing out similarities between Reynolds’ findings and Pavlovian overshadowing.