Down, N., Skoumbourdis, E., Walsh, M. et al. 2005. Pole-and-collar training: A discussion by the Laboratory Animal Refinement and Enrichment Forum. Animal Technology and Welfare 4, 157-161.

Experiences with the pole-and-collar training training are shared. Yes, most monkeys can be trained but some cannot, or let's say they should not be trained because their personality -- which is presumably conditioned through negative experiences with people -- is very difficult to deal with.