AN INVERSE RELATIONSHIP BETWEEN BASELINE FIXED‐INTERVAL RESPONSE RATE AND THE EFFECTS OF A TANDEM RESPONSE REQUIREMENT

Previous experiments examining the effects of adding a tandem fixed‐ratio response requirement on fixed‐interval schedule performance have reported inconsistent results. One variable that may account for such inconsistencies is the baseline response rate in the fixed‐interval condition. This possibility was investigated in the present study. Rats were given histories with either interresponse times greater than 11 s or fixed‐ratio 40 schedules of reinforcement, which engendered either relatively low or high rates of responding, respectively, in the subsequent fixed‐interval condition. A tandem ratio response requirement (fixed‐ratio 9) was then introduced. The effects of adding this tandem response requirement were inversely related to the baseline fixed‐interval response rates; low rates of responding in the fixed‐interval condition were markedly increased, whereas high rates of responding were relatively unaffected. This inverse relationship appears to be similar to the rate‐dependent relations observed in behavioral pharmacology. These results may provide an explanation for the inconsistent findings reported in previous studies on tandem fixed‐interval fixed‐ratio schedules and suggest that principles of behavioral pharmacology research may be applicable to the study of the effects of nonpharmacological variables on schedule‐controlled behavior. 1988 Society for the Experimental Analysis of Behavior