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Concurrent second-order schedules: Some effects of variations in response number and duration.
Sealey, D. M., Sumpter, C. E., Temple, W., & Foster, T. M. (2005).
Concurrent second-order schedules: Some effects of variations in response number
and duration.
Journal of the Experimental Analysis of Behavior, 84, 19-35.
To 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 fixed-ratio 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.
Key words: concurrent schedules, second-order schedules, bias, response
requirement, fix and sample, key peck, hen