Abstract # 46:

Scheduled for Thursday, June 19, 2008 05:00 PM-07:00 PM: Session 4 (Ball Rooms A and B) Poster Presentation

Juvenile pigtailed macaques' (Macaca nemestrina) performance errors on a spatial search task: differentiating between working memory and inhibitory control

S. E. Ward1 and D. J. Mandell2
1Yerkes National Primate Research Center, 954 Gatewood Rd NE, Atlanta, GA 30329, USA, 2Department of Psychology, University of Amsterdam
     ¬†Spatial search tasks have been used as putative measures of Executive Functioning with both humans and nonhumans. The subject is required to "search" an array of locations to find a target or reward, with the optimal performance being searching each location only once. The meaning of the errors on this type of task has been interpreted two ways; either as evidence of working memory failure or as evidence of poor inhibitory control. In order to explore whether working memory could be dissociated from inhibitory processes, 12 juvenile pigtailed macaques (M. nemestrina) were tested on a 4 location search task for 15 days. Data were summarized across 3 test days into the average number of searches to find the reward, the number of searches to a previously searched location, which indicated memory errors, and the number of consecutive searches to the same location, which indicated inhibition errors. Across the 15 days of testing, the animals did not show a significant change in the average number of searches it took to find the reward [F(4,40)=0.62, p=0.65]. However, animals did show a significant decrease in the number memory errors [F(4,40)=4.29, p=0.01] as well as substantial decreases in the proportion of inhibition errors [F(4,40)=10.33, p<0.001] over this time. These results suggest that working memory and inhibitory control can be dissociated and that decreases in repetitive behavior lead to improvement on the task.