A yoked-chamber comparison of concurrent and multiple schedules: the relationship between component duration and responding.

Two experimental chambers were electrically connected so that the component selected by a pigeon confronting concurrent variable-interval schedules in one chamber could be successively presented as a multiple schedule to a second pigeon in the other chamber. Component duration was regulated by the use of a changeover delay, the value of which was systematically varied between 0 and 30 sec. It was found that the relative local response rates on the preferred key (absolute response rate to that component divided by the sum of the absolute response rates during both components) tended to increase with increasing component durations for the birds in the concurrent chamber, but decreased for the birds in the multiple chamber. These data support the interpretation that there are fundamental differences in the mode of responding to multiple and concurrent schedules. Based on these findings, it was concluded that previous demonstrations of matching on multiple schedules do not establish that response allocation is controlled by a process equivalent to that found on choice paradigms. It now appears that matching on multiple (but not concurrent) schedules is a consequence of selecting short component durations. The implications of these data for Herrnstein's (1970) and Rachlin's (1973) formulations of the relationship between multiple and concurrent schedules are examined.