Andrzejewski, M. E., Cardinal, C. D., Field, D. P., Flannery, B. A., Johnson, M., Bailey, K., & Hineline, P. N. (2005).
Pigeons’ choices between fixed-interval and random-interval schedules: Utility of variability?
Journal of the Experimental Analysis of Behavior, 83, 129-145.
Pigeons’ choosing between fixed-interval and random-interval schedules of
reinforcement was investigated in three experiments using a discrete-trial
procedure. In all three experiments, the random-interval schedule was
generated by sampling a probability distribution at an interval (and in
multiples of the interval) equal to that of the fixed-interval schedule.
Thus the programmed delays to reinforcement on the random alternative were
never shorter and were often longer than the fixed interval. Despite this
feature, the fixed schedule was not strongly preferred. Increases in the
probability used to generate the random interval resulted in decreased
preferences for the fixed schedule. In addition, the number of consecutive
choices on the preferred alternative varied directly with preference, whereas
the consecutive number of choices on the nonpreferred alternative was fairly
constant. The probability of choosing the random alternative was unaffected
by the immediately prior interval encountered on that schedule, even when it
was very long relative to the average value. The results loosely support
conceptions of a "preference for variability" from foraging theory and the
“utility of behavioral variability” from human decision-making literatures.
Key words: choice, variability, foraging, fixed interval, random
interval, key peck, pigeon