RATIO RESPONDING AS A FUNCTION OF CONCURRENT AVOIDANCE SCHEDULES, YOKED SHOCKS, AND RATIO VALUE

Fixed‐ratio food‐reinforced responding in rats was studied alone and with concurrent shock avoidance or with concurrent response‐independent shocks matched to those that occurred in the avoidance condition. Under each condition, fixed‐ratio size was increased over successive daily sessions. Fixed‐ratio response rate generally passed through a maximum as a function of fixed‐ratio size. Decreased fixed‐ratio responding at values beyond the maximum occurred when (1) the time to complete a fixed ratio approximated the response‐shock interval of the avoidance schedule, (2) the shock rate increased, and/or (3) the ratio requirements were so high that ratio strain occurred. Avoidance rates decreased slightly as fixed‐ratio size increased.