Local analysis of behaviour in the adjusting-delay task for assessing choice of delayed reinforcement.
The adjusting-delay task introduced by Mazur (Quantitative analyses of behavior: V. The effect of delay and of intervening events on reinforcement value, 1987, pp. 55-73) has been widely used to study choice of delayed reinforcers. This paradigm involves repeated choice between one reinforcer delivered after a fixed delay and another, typically larger, reinforcer delivered after a variable delay; the variable delay is adjusted depending on the subject's choice until an equilibrium point is reached at which the subject is indifferent between the two alternatives. Rats were trained on a version of this task and their behaviour was examined to determine the nature of their sensitivity to the adjusting delay; these analyses included the use of a cross-correlational technique. No clear evidence of sensitivity to the adjusting delay was found. A number of decision rules, some sensitive to the adjusting delay and some not, were simulated and it was observed that some effects usually supposed to be a consequence of delay sensitivity could be generated by delay-independent processes, such as a consistent, unchanging relative preference between the alternatives. Consequently, the use of explicit analysis of delay sensitivity is advocated in future research on delayed reinforcement.
Cardinal
Rudolf N
RN
Department of Experimental Psychology. University of Cambridge, UK. rudolf.cardinal@pobox.com
Daw
Nathaniel
N
Robbins
Trevor W
TW
Everitt
Barry J
BJ
D000818:Animals; D002755:Choice Behavior / Q000502:physiology*; D003198:Computer Simulation; D008297:Male; D008960:Models, Psychological; D051381:Rats; D012055:Reinforcement Schedule