A self-adjustment procedure for measuring the visual acuity of rhesus monkeys

A visual acuity testing procedure is described which uses a self-adjustment procedure combined with shock avoidance and punishment. The S adjusts the size of the gap opening in Landolt rings by pressing levers. Correct trials decrease the size of the gap opening and are followed by a tone; incorrect trials increase the size of the gap opening and are followed by shock. The number of correct and incorrect trials needed to change the gap-opening size can be varied.