Mazur, James E. (2007).
Discriminated timeout-avoidance in pigeoChoice in a successive-encounters procedure and hyperbolic decay of reinforcementns.
Journal of the Experimental Analysis of Behavior, 88, 73-85.
Pigeons responded in a successive-encounters procedure that consisted of a search state, a choice state,
and a handling state. The search state was either a fixed-interval or mixed-interval schedule presented
on the center key of a three-key chamber. Upon completion of the search state, the choice state was
presented, in which the center key was off and the two side keys were lit. A pigeon could either accept
a delay followed by food (by pecking the right key) or reject this option and return to the search state
(by pecking the left key). During the choice state, a red right key represented the long alternative (a
long handling delay followed by food), and a green right key represented the short alternative (a short
handling delay followed by food). In some conditions, both the short and long alternatives were fixedtime
schedules, and in other conditions both were mixed-time schedules. Contrary to the predictions of
both optimal foraging theory and delay-reduction theory, the percentage of trials on which pigeons
accepted the long alternative depended on whether the search and handling schedules were fixed or
mixed. They were more likely to accept the long alternative when the search states were fixed-interval
rather than mixed-interval schedules, and more likely to reject the long alternative when the handling
states were fixed-time rather than mixed-time schedules. This pattern of results was in qualitative
agreement with the predictions of the hyperbolic-decay model, which states that the value of a reinforcer
is inversely related to the delay between a choice response and reinforcer delivery.
Key words: Choice, successive-encounters procedure, hyperbolic-decay model, optimal foraging
theory, delay-reduction theory, key peck, pigeons