Accommodation and the Acquisition of Distant Targets by Observers with Superior Vision

Abstract

The visual accommodation ability of young observers with healthy eyeballs has typically been underestimated. A series of experiments and demonstrations was conducted to study how a pilot might use his eyes to optimize target acquisition performance in different visual environments. Observers with uncorrected far acuities of 20/20 or better were selected for participation. Target acquisition tasks were performed while accommodation was simultaneously monitored with an infrared optometer. The target was always small and located at optical infinity. The average dark focus was more distant than is typically reported and tended to shift outwards with experience on the optometer. When observers were provided with distance information, half were apparently able to “look through” near peripheral texture in order to optimize accommodation accuracy and target detection performance. Although most observers were capable of using imagery to shift their accommodation outwards in the dark, this did not predict the ability to “look through” near texture. In a subsequent demonstration, two observers were able to focus and defocus small targets on demand. Implications for military pilots, many of whom have superior vision, are discussed.