Manual laterality and task complexity in De Brazza's monkey (Cercopithecus neglectus).

We investigated manual specialisation of six Brazza monkeys, both under structured experimental conditions and while they engaged in unconstrained natural behaviour. Five tasks that varied in complexity, degree of visual guidance, and bimanual coordination were used in the experimental condition. Individual preferences were revealed for each task, and in the case of simple tasks the position of a monkey relative to the task device was shown to impact on manual preference. Strength of laterality and performance were not found to be related. Task complexity influenced strength, but not direction, of manual preference. The small number of animals precluded generalisation to population preferences but the large number of observations and choice of tasks can serve as model for the study of manual preferences in primates.