Abstract # 85:

Scheduled for Thursday, June 20, 2013 07:00 PM-09:00 PM: Session 9 (SG Foyer ABC) Poster Presentation


E. L. Nelson1, A. Figueroa2, M. F. Gonzalez2, S. Albright1 and A. Gil1
1Florida International University, Department of Psychology, 11200 S.W. 8th St, Miami, FL 33199, USA, 2Department of Biological Sciences, Florida International University, 11200 S.W. 8th St, Miami, FL 33199

The spider monkey is a unique model for primate laterality because it lacks thumbs but has a prehensile tail capable of grasping, much like an additional hand. We first examined hand use with the coordinated bimanual TUBE task, a standard measure in the field not previously administered to spider monkeys. We identified 6 monkeys as left-handed, 2 as right-handed, and 1 as having no preference with the formula (Right-Left/Right+Left), and cutoff scores of ±0.20 to denote preferences. We then presented monkeys with the BOWL task, a novel challenge where the tail must be used to pull a bowl suspended on chain-link outside the enclosure. One hand then stabilized the bowl, while the other hand retrieved a grape. Monkeys were given 10 trials per day on 6 non-consecutive days. Four monkeys performed this tail-hand sequence. Hand use on the BOWL task varied from the TUBE task. Two monkeys switched from left (-0.20, -0.93) to right preference (0.83, 0.93); one switched from left (-0.40) to no preference (-0.07); and one was left on both hand tasks (-1.00, -0.93). All monkeys were exclusively left-side tail lateralized (tail to left of midline; all tail scores -1.00). Monkeys may have prioritized the tail action, shifting preferences for the secondary manual action. Sequence of action, in addition to task demands, may affect the degree and direction of behavioral asymmetries in primates.