CHOICE AND RATE OF REINFORCEMENT^1,²

TLDR

Pigeons presented with two concurrent initial stimuli chose between two terminal stimuli, one of which delivered reinforcement at a rate three times higher than the other, and choice behavior is theorized to depend on the relative reduction in expected time to reinforcement offered by each terminal link. Three different pairs of identical but independent variable‑interval schedules controlled entry into the terminal links. When intermediate schedules were used, pigeons matched reinforcement rates, consistent with prior studies, but with larger, smaller, or unequal variable‑interval schedules, choice proportions failed to match reinforcement proportions.

Abstract

Pigeons' responses in the presence of two concurrently available (initial‐link) stimuli produced one of two different (terminal‐link) stimuli. The rate of reinforcement in the presence of one terminal‐link stimulus was three times that of the other. Three different pairs of identical but independent variable‐interval schedules controlled entry into the terminal links. When the intermediate pair was in effect, the pigeons distributed their (choice) responses in the presence of the concurrently available stimuli of the initial links in the same proportion as reinforcements were distributed in the mutually exclusive terminal links. This finding was consistent with those of earlier studies. When either the pair of larger or smaller variable‐interval schedules was in effect, however, proportions of choice responses did not match proportions of reinforcements. In addition, matching was not obtained when entry into the terminal links was controlled by unequal variable‐interval schedules. A formulation consistent with extant data states that choice behavior is dependent upon the amount of reduction in the expected time to primary reinforcement, as signified by entry into one terminal link, relative to the amount of reduction in expected time to reinforcement signified by entry into the other terminal link.