A visual exploration apparatus for infant monkeys.

Abstract

An apparatus was constructed to study visual exploration in infant rhesus macaques. It consisted of an enclosed two-chamber box with a peephole at each end. The floor was made of stainless steel bars, and the walls and top were made of Plexiglas covered with Masonite. The peepholes were recessed in alcoves. An infrared photobeam crossed the alcoves in front of each peephole so that whenever the monkey looked out its head broke the photobeam. Slides of complex scenes were projected on back-lit frosted plexiglas screens. The monkey's position in the box was monitored by its resistance across the floor bars. Whenever the monkey went from one side of the box to the other, a new slide was projected on the side just entered. The session progressed until either 40 slides had been displayed on each side or 30 minutes had elapsed. The primary behavioral measures taken were session length, number of slides displayed, time spent looking, number of looks, and time spent looking at the first slide on each side. Serveral other performance measures were derived from these basic measures: time looked/slide, number of looks/slide, and average length of look (time looked/number of looks). The monkeys readily performed in this apparatus, looking out through the peepholes for an average of about 14% of each session with attentional episodes of just under 3 seconds. This apparatus has proven useful for automatically measuring visual exploration behavior in infant monkeys and can be readily adapted for use in many types of studies.