Shull, R. L., Grimes, J. A., & Bennett, J. A. (2004).
Bouts of responding: The relation between bout rate and the rate of
variable-interval reinforcement.
Journal of Experimental Analysis of Behavior,
81, 65-83.
By nose poking a lighted key, rats obtained food pellets on either a variable-
interval schedule of reinforcement or a schedule that required an average of
four additional responses after the end of the variable-interval component (a
tandem variable-interval variable-ratio 4 schedule). With both schedule types,
the mean variable interval was varied between blocks of sessions from 16 min to
0.25 min. Total rate of key poking increased similarly as a function of the
reinforcer rate for the two schedule types, but response rate was higher with
than without the four-response requirement. Analysis of log survivor plots of
interresponse times showed that key poking occurred in bouts. The rate of
initiating bouts increased as a function of reinforcer rate but was either
unaffected or was decreased by adding the four-response requirement. Within-bout
response rate was insensitive to reinforcer rate and only inconsistently
affected by the four-response requirement. For both kinds of schedule, the ratio
of bout time to between-bout pause time was approximately a power function of
reinforcer rate, with exponents above and below 1.0.
Key words: bouts, log survivor plot, variable-interval schedule,
tandem ratio, time allocation, key poke, rats