Cleaveland, J. M. (1999).
Interresponse-time sensitivity during discrete-trial and free-operant concurrent variable- interval schedules.
Journal of the Experimental Analysis of Behavior,
72, 317-339.
Two experiments investigated the sensitivity of pigeons' choice
to elapsed time since the last response (i.e., to interresponse
time [IRT]) during concurrent variable-interval variable-interval
schedules. Experiment 1 used a two-key discrete- trial procedure
with variable intertrial intervals. Experiment 2 employed a
three-key free-operant procedure. In both experiments choice was
found to be a function of the active-schedule IRT, defined as the
time since the most recent response. Monte Carlo simulations show
how this finding permits the joining of several seemingly
incompatible data sets held to both support and contradict a kind
of choice strategy, termed momentary maximizing, which
attempts to maximize momentary reinforcement probabilities. The
studies suggest that only two variables are needed to describe
the static molecular structure of concurrent variable-interval
choice: active-schedule IRTs and "response states"
consisting of the last one or two schedule choices.
Key words: interresponse time, momentary maximizing, Markov
chains, timing, variable-interval schedules, pigeons