Pigtail macaque performance on a challenging joystick task has important implications for enrichment and anxiety...

The purpose of this study was to extend previous findings on joystick task engagement by a group of pigtail macaques. The goals were to determine the influence of task difficulty on daily levels of task activity and to test the hypothesis that previously identified preferences among identical devices at different locations derived largely from the level of anxiety induced at each location. It was found that the number of daily trials decreased when the task was made more difficult, with more time required to complete each trial with the difficult task. Preferences among locations became more pronounced with the more difficult task. Analysis of errors made on devices at different locations supported the view that preferences did derive, at least in part, from levels of induced anxiety. Locations of enrichment devices may influence not only amount of use but also levels of anxiety in captive monkeys.