Dutch experimenters show that Capuchin monkeys are happy with cucumber as a reward for handing the experimenter rocks, but when they are allowed to observe another monkey receiving grapes for the same task, they refuse to continue. Also the one in the video appears hilariously pissed off at the experimenter and smacks the table, demanding grapes.
I’m interested in whether the grape-rewarded monkey would experience guilt, or sympathy for the other monkey; while he can see the cucumber-rewarded monkey just as well, he sure isn’t sharing his superior reward. Also curious whether the cucumber-rewarded monkey experiences anger toward his better-rewarded cohort. He is certainly angry at the experimenter. Perhaps the grape-rewarded monkey would garner resentment and lose standing with other monkeys for his good fortune.