Studies of the Interaction of Rhesus Macaques with Touchscreen Monitors during Observation of Low-Frequency Test Images

Behavioral experiments were performed in which rhesus macaques were trained to interact with a computer using a touchscreen. Stimuli consisted of semitone images of Gabor elements with low spatial frequency with different contrast levels. The monkeys’ task was to touch the screen with the paw at the site at which the target stimulus appeared, which was followed by automatic delivery of a food or drink (juice) reward. Contrast was gradually decreased when correct responses were obtained. A two-way forced choice paradigm was used to measure the threshold contrast at which the monkeys could detect the appearance of low-frequency images. Decreases in the spatial frequency of stimuli were accompanied by decreases in contrast sensitivity, while reaction times increased. These data widen our understanding of primate activity in a virtual environment and make it possible to model and study a variety of human diseases.