Influence of a visual landmark shift on memory-guided reaching in the monkey

Reach and gaze data were collected from one female Macaca mulatta monkey (ML) trained to perform a memory-guided reaching task to determine the influence of allocentric cue shifts on reaching responses in the non-human primate. A landmark (4 ‘dots’ spaced 10° apart forming the corners of a virtual square) was presented at 1 of 15 locations on a touch screen. The landmark either reappeared at the same location (stable landmark condition) or shifted by 8° in one of 8 directions (landmark shift condition). ‘No-landmark’ controls were the same, but without the landmark. The presence of a stable landmark increased the accuracy of both gaze and touch responses and the precision of gaze. In the landmark shift condition, reaches shifted partially (mean = 29 %) with the landmark. Overall, these data suggest that the monkey is influenced by visual landmarks when reaching to remembered targets in a similar way as humans.