The reversed work-ethic effect: Monkeys avoid stimuli associated with high-effort1

Abstract

We investigated how different numbers of responses prior to the presentation of a stimulus influenced preferences for the stimulus in three Japanese monkeys (Macaca fuscata). Monkeys were trained for two kinds of simultaneous discriminations that followed a high-effort or a low-effort response. In probe test trials, the stimulus that followed the high-effort and the stimulus that followed the low-effort response during discriminations were presented simultaneously. All monkeys chose stimuli that in training followed a low-effort response. This result suggested that monkeys avoided stimuli that followed high-effort responses because of the association between those stimuli and the preceding greater effort. The present result is consistent with our previous study conducted with humans, but contradicts analogous studies carried out with pigeons that reported either opposite results (i.e. pigeons preferred the stimuli after high-effort) or non-biased preferences. The differences between mammals and birds are discussed in terms of the lack of a successive negative contrast effect in birds.