Lattal, K. A., & Abreu-Rodrigues, J. (1997).
Response-independent events in the behavior stream.
Journal of the Experimental Analysis of Behavior,
68, 375-398.
The metaphor of the behavior stream provides a framework for
studying the effects of response-independent food presentations
intruded into an environment in which operant responding of
pigeons was maintained by variable-interval schedules. In the
first two experiments, response rates were reduced when
response-independent food was intruded during the
variable-interval schedule according to a concomitantly present
fixed-time schedule. These reductions were not always an orderly
function of the percentage of response-dependent food. Negatively
accelerated patterns of key pecking across the fixed-time period
occurred in Experiment 1 under the concomitant fixed-time
variable-interval schedules. In Experiment 2, positively and
negatively accelerated and linear response patterns occurred even
though the schedules were similar to those used in Experiment 1.
The variable findings in the first two experiments led to three
subsequent experiments that were designed to further illuminate
the controlling variables of the effects of intruded
response-independent events. When the fixed and variable
schedules were correlated with distinct operanda by employing a
concurrent fixed-interval variable-interval schedule (Experiment
3) or with distinct discriminative stimuli (Experiments 4 and 5),
negatively accelerated response patterns were obtained. Even in
these latter cases, however, the response patterns were a joint
function of the physical separation of the two schedules and the
ratio of fixed-time or fixed-interval to variable-interval
schedule food presentations. The results of the five experiments
are discussed in terms of the contributions of both reinforcement
variables and discriminative stimuli in determining the effects
of intruding response-independent food into a stream of operant
behavior.
Key words: concurrent schedule, conjoint schedule, concomitant
schedule, temporal control, response patterns, key peck, pigeons