Concurrent performances: synthesizing rate constancies by manipulating contingencies for a single response.

An earlier experiment scheduled variable-interval reinforcement for pigeons' pecks on one key, and variable-interval reinforcement alternating with extinction, in a multiple schedule, for pecks on a second key. During the second key's extinction component, first-key pecking was relatively slow and continuous, rarely interrupted by second-key pecking; during the variable-interval component, first-key pecking was frequently interrupted by second-key pecking. When changeover delays operated, so that reinforced pecks on one key could not follow closely upon changeovers from the other key, rapid first-key pecking between interruptions compensated sufficiently for the time lost in second-key pecking that the overall rate of first-key pecking remained roughly constant across the alternating multiple-schedule components. The present experiments duplicated, on a single key, the temporal pattern of first-key pecking generated in the earlier experiments: components of continuous key availability were alternated with components of interrupted key availability. Approximately constant overall rates of responding were observed with a single-key equivalent of a changeover delay scheduled after interruptions and with manipulations of the on-off durations of the interruption cycle. Rate constancies in the original concurrent situation presumably depended on analogous contingencies that operated upon the concurrent responses, rather than on any constant "reserve" of responses.