Sealey, Diane M.Sumpter, Catherine E.Temple, WilliamFoster, T. Mary2010-02-012010-02-012005Sealey, D. M., Sumpter, C. E., Temple, W. & Foster, M. (2005). Concurrent second-order schedules: some effects of variations in response number and duration. Journal of the Experimental Analysis of Behavior, 84(1), 19-35.https://hdl.handle.net/10289/3540To examine the effects on concurrent performance of independent manipulations of response-unit duration and number, 6 hens were exposed to concurrent second-order schedules of reinforcement. Each first-order operant unit required completion of a fixed-ratio schedule within the time specified by a fixed-interval schedule, with one further response completing the fixed-interval schedule. The fixedratio and fixed-interval requirements comprising the first-order operant units were systematically and independently varied under three pairs of concurrent variable-interval schedules to produce differences in the first-order response and duration requirements (response and duration differentials). These manipulations produced consistent changes in response, time, and operant-unit biases. A 1:4 response differential biased the time and operant-unit measures towards the smaller fixed ratio, but to a degree less than the imposed response differential. The response-based biases favored the larger fixed ratio. Duration differentials of 4:1 and 8:1 biased the response and operant-unit measures towards the shorter fixed interval, again less than the imposed duration differential, but the time biases remained close to zero. Both sorts of differentials acted to bias operant-unit completions more systematically than the other measures, but undermatching to the differentials occurred. The undermatching appears to have arisen from a pattern of fix and sample (in which visits to the less preferred alternative involved only a single completed operant unit) under combinations of unequal operant-unit requirements and reinforcer rates. The response and time bias measures appeared to arise as by-products of the changes in operant-unit completions.application/pdfenThis article has been published in the journal: Journal of the Experimental Analysis of Behavior. Used with permission.concurrent schedulessecond-order schedulesbiasresponse requirementfix and samplekey peckhenJournal Article10.1901/jeab.2005.104-04