摘要：To investigate whether 2 chimpanzees had expectationsregarding the outcome of their responses on a computerized task,food reward that typically was given for correct responses waswithheld on some correctly completed trials. There were two typesof these probe trials: those which the chimpanzees performedcorrectly on their own, and those during which the chimpanzeesneeded the experimenter's assistance to complete the trialcorrectly. For both chimpanzees, reward procurement behaviorsdirected toward the experimenter occurred significantly more oftenon correctly completed probe trials than on incorrectly completedtrials. This indicated increased expectation of food reward oncorrect trials as compared to incorrect trials. For 1 of the 2chimpanzees, reward procurement behaviors were significantlymore likely to occur on probe trials on which the chimpanzeereceived no assistance from the experimenter than on trials inwhich the experimenter assisted the chimpanzee. This behavioraldifference was not predicated on reinforcement history, as allcorrectly completed nonprobe trials were rewarded whether or notassistance was provided by the experimenter. These data indicatethat this chimpanzee may have a rudimentary sense of "equity"regarding what outcome should accompany the successfulcompletion of trials that is dependent on the level of assistanceprovided by an experimenter during the trial.
