The maintenance of key pecking by stimulus-contingent and response-independent food presentation.

Gamzu, E., & Schwartz, B. (1973). The maintenance of key pecking by stimulus-contingent and response-independent food presentation. Journal of the Experimental Analysis of Behavior, 19, 65-72.

Three naive pigeons were exposed to a series of two-component multiple schedules of response-independent food presentation. The component schedules were sometimes identical (non-differential procedures) and sometimes different (differential procedures). High rates of key pecking were maintained in all the differential procedures, and pecking decreased substantially in non- differential procedures, even when the frequency of food presentation in non-differential procedures was higher than in differential procedures. It is suggested that the high rates of key pecking were maintained not by adventitious response- reinforcer contingencies, but by differential contingencies between the stimulus (keylight) and food. The role of such contingencies in the phenomenon of behavioral contrast is discussed.