PROCRASTINATION BY PIGEONS WITH FIXED-INTERVAL RESPONSE REQUIREMENTS

Two experiments studied the phenomenon of procrastination, in which pi geons chose a larger, more delayed response requirement over a smaller , more immediate response requirement. The response requirements were fixed-interval schedules that did not lead to an immediate food reinfo rcer, but that interrupted a 55-s period in which food was delivered a t random times. The experiments used an adjusting-delay procedure in w hich the delay to the start of one fixed-interval requirement was vari ed over trials to estimate an indifference point-a delay at which the two alternatives were chosen about equally often. Experiment 1 found t hat as the delay to a shorter fixed-interval requirement was increased , the adjusting delay to a longer fixed-interval requirement also incr eased, and the rate of increase depended on the duration of the longer fixed-interval requirement. Experiment 2 found a strong preference fo r a fixed delay of 10 s to the start of a fixed-interval requirement c ompared to a mixed delay of either 0 or 20 s. The results help to dist inguish among different equations that might describe the decreasing e ffectiveness of a response requirement with increasing delay, and they suggest that delayed reinforcers and delayed response requirements ha ve symmetrical but opposite effects on choice.