Podlesnik, C. A., Jimenez-Gomez, C., Ward, R. D. & Shahan, T. A.(2006).
Resistance to change of responding maintained by unsignaled delays to
reinforcement: A response-bout analysis.
Journal of the Experimental Analysis of Behavior, 85, 329-347.
Previous experiments have shown that unsignaled delayed reinforcement
decreases response rates and resistance to change. However, the effects
of different delays to reinforcement on underlying response structure
have not been investigated in conjunction with tests of resistance to
change. In the present experiment, pigeons responded on a three-component
multiple variable-interval schedule for food presented immediately, following
brief (0.5 s), or following long (3 s) unsignaled delays of food reinforcement.
Baseline response rates were lowest in the component with the longest delay;
they were about equal with immediate and briefly delayed reinforcers. Resistance
to disruption by presession feeding, response-independent food during the
intercomponent interval, and extinction was slightly but consistently lower
as delays increased. Because log survivor functions of interresponse times
(IRTs) deviated from simple modes of bout initiations and within-bout responding,
an IRT-cutoff method was used to examine underlying response structure.
These analyses suggested that baseline rates of initiating bouts of responding
decreased as scheduled delays increased, and within-bout response rates tended
to be lower in the component with immediate reinforcers. The number of
responses per bout was not reliably affected by reinforcer delay, but
tended to be highest with brief delays when total response rates were higher
in that component. Consistent with previous findings, resistance to change of
overall response rate was highly correlated with resistance to change of
bout-initiation rates but not with within-bout responding. These results
suggest that unsignaled delays to reinforcement affect resistance to change
through changes in the probability of initiating a response bout rather than
through changes in the underlying response structure.
Key words: behavioral momentum theory, resistance to change, unsignaled delay of reinforcement, multiple schedules, bouts, key peck, pigeon