Investigation of laterality in terms of hand preference and hand dominance in Sapajus apella primates

Abstract

ABSTRACT

OBJECTIVE:

To quantify individual variability in the laterality of Sapajus apella primates to determine the occurrence of hand preference and hand dominance, or both, through two motor tests.

MATERIALS AND METHODS

:Seven adult male monkeys were subjected to sessions of habituation to the experimenters and experimental apparatus, followed by 20 sessions of the staircase and Brinkman board motor tests, which allow the measurement of reach and grip skills, and the precision in the pincer grasp. Parameters such as withdrawal latency for the first reward, usage of switched hand, time to withdraw all rewards, and loss of the reward were collected for each hand individually. Sequence analysis of reward withdrawal on the Brinkman board was performed to observe the establishment of motor patterns.

RESULTS:

Significant differences were observed between the data obtained for the right and left hands for all animals, with important variations in manual preference and manual dominance, as well as changes in the motor pattern while performing the test with indications of learning induced by it.

CONCLUSION:

Monkeys showed a hand preference in performing motor tasks, with a higher prevalence of preference on the right side, with no correspondence between hand preference and hand dominance for each animal.