Morrin, Y. 2020. No bullies allowed! Co-operative feeding as a means to enhance the welfare of 'sub-ordinates'. RATEL (Journal of the Association of British and Irish Wild Animal Keepers) 47(1), 18-19.
This article describes a protocol for training capuchins for co-operative feeding. Three months after beginning the training, the two dominant individuals consistently stay stationed, calmly focused, and the keeper is able to hand the subordinate a treat at her station as they watch, then reward them for staying calm.