Adaptation of Divers to Curvature Distortion under Water

Abstract

A diver's face-mask causes ‘ pin-cushion ’ distortion for objects seen under water. The apparent curvature in depth of a straight line was measured for seven divers in air and water before and after a half-hour dive in the sea. Approximately 25 per cent of full adaptation to the optical distortion occurred during the dive, with a corresponding negative after-effect in air. The apparent curvature of the line was also measured for 16 novices and 15 experienced divers both in air and immediately on entering the water. The experienced divers showed some initial adaptation, while the novices showed none. This result suggests that the experienced divers had acquired a ‘ situation-contingent ’ visual response.