Shull, R. L. (2004).
Bouts of responding on variable-interval schedules: Effects of
deprivation level.
Journal of Experimental Analysis of Behavior,
81, 155-167.
Rats obtained food pellets on a variable-interval schedule of reinforcement by
nose poking a lighted key. After training to establish baseline performance
(with the mean variable interval set at either 60, 120, or 240 s), the rats were
given free access to food during the hour just before their daily session. This
satiation operation reduced the rate of key poking. Analysis of the
interresponse time distributions (log survivor plots) indicated that key poking
occurred in bouts. Prefeeding lengthened the pauses between bouts, shortened the
length of bouts (less reliably), and had a relatively small decremental effect
on the response rate within bouts. That deprivation level affects mainly
between-bout pauses has been reported previously with fixed-ratio schedules.
Thus, when the focus is on bouts, the performances maintained by variable-
interval schedules and fixed-ratio schedules are similarly affected by
deprivation.
Key words: bouts, deprivation, satiation, log survivor plot, variable-
interval schedule, key poke, rats