Peng Daniel, Iqbal Zohaib, Zentall Thomas R
Department of Psychology, University of Kentucky.
J Exp Psychol Anim Learn Cogn. 2025 Jun 30. doi: 10.1037/xan0000397.
In the Ephemeral Reward Task, a subject is presented with a choice between two stimuli, A and B. If it chooses A, it gets a reward and the trial is over. If it chooses B, it gets a reward and it can then respond to A, to obtain a second reward. Wrasse (cleaner fish) and parrots learn to choose B optimally within 100 trials, primates may also learn, whereas pigeons and rats do not. We attempted to determine why pigeons have difficulty learning their task. First, we tested the hypothesis that pigeons fail because the outcome after choice of A is similar to the outcome after a response to A given choice of B. For group AC, after the choice of B, stimulus A changed to stimulus C. For group BC, after the choice of stimulus B, stimulus B changed to stimulus C. For group BB, after the choice of stimulus B, stimulus B remained for a second reward. None of the three groups learned to choose optimally. In Experiment 2, the probability of reward for choice of stimulus A or B was reduced to 50%. Pigeons learned to choose optimally. We suggest that the difference in value between one and two rewards may not be as great as the difference in value between 0.5 and one reward. (PsycInfo Database Record (c) 2025 APA, all rights reserved).
在短暂奖励任务中，向受试者呈现两种刺激A和B供其选择。如果它选择A，就会得到奖励，试验结束。如果它选择B，也会得到奖励，然后它可以对A做出反应，以获得第二个奖励。隆头鱼（清洁鱼）和鹦鹉在100次试验内就能学会最佳地选择B，灵长类动物也可能学会，而鸽子和大鼠则学不会。我们试图确定鸽子难以学会其任务的原因。首先，我们检验了这样一个假设，即鸽子失败是因为选择A后的结果与在选择B后对A做出反应后的结果相似。对于AC组，在选择B后，刺激A变为刺激C。对于BC组，在选择刺激B后，刺激B变为刺激C。对于BB组，在选择刺激B后，刺激B保持不变以供获得第二个奖励。这三组中没有一组学会最佳选择。在实验2中，选择刺激A或B的奖励概率降低到了50%。鸽子学会了最佳选择。我们认为，一个奖励和两个奖励之间的价值差异可能不如0.5个奖励和一个奖励之间的价值差异那么大。（PsycInfo数据库记录（c）2025美国心理学会，保留所有权利）
