ABSTRACT: Stimuli associated with less effort or with shorter delays to reinforcement are generally preferred over those associated
with greater effort or longer delays to reinforcement. However, the opposite appears to be true of stimuli thatfollow greater effort or longer delays. In training, a simple simultaneous discrimination followed a single peck to an initial stimulus
(S+FR1 S−FR1) and a different simple simultaneous discrimination followed 20 pecks to the initial stimulus (S+FR20 S−FR20). On test trials, pigeons preferred S+FR20 over S+FR1 and S−FR20 over S−FR1. These data support the view that the state of the animal immediately prior to presentation of the discrimination affects
the value of the reinforcement that follows it. This contrast effect is analogous to effects that when they occur in humans
have been attributed to more complex cognitive and social factors.
Psychonomic Bulletin & Review 04/2012; 7(1):100-106. · 2.61 Impact Factor