Responses to the underwater distortions of visual stimuli. SMRL Report No. 541.

Abstract : This report is an account of underwater experiments on size and distance perception and hand-eye coordination, conducted to find, first, what the diver perceives, and secondly, means of aiding him to respond adequately to his unusual environment. Results are reported on two aspects of underwater vision, apparent distance and hand-eye coordination. The accuracy of distance estimates underwater varies greatly from underestimation at near distances, to overestimation at far distances. Viewing through turbid water rather than clear water greatly increases the tendency toward overestimation. The ability of subjects to perform motor responses adequately, using the distorted stimulation underwater, has been measured and shown to vary with the time spent in underwater activities.