A hypothesis-based approach to clinical psychophysics and to the design of visual tests: the Proctor Lecture.

TL;DR: A hypothesis of visual processing is outlined that offers a guide to the design of tests for revealing forms of visual loss that are hidden from detection by the classic tests of visual function and examples of the application of the hypothesis are given.

Abstract: Over the past 30 years or so, it has become increasingly clear that even gross defects of visual function can be hidden from detection by classic clinical tests. In this lecture, I have outlined a hypothesis of visual processing that offers a guide to the design of tests for revealing forms of visual loss that are hidden from detection by the classic tests of visual function and have given examples of the application of the hypothesis. A further point bears on the growing involvement of ophthalmologists and vision scientists in developing screening tests for individuals who must perform tasks that require high skills in visually guided motor action, such as driving a car or truck, flying a passenger aircraft, flying a medical emergency helicopter, and providing visual surveillance in air–sea rescue operations. The hypothesis can guide the design of screening tests that are specific for the task to be performed. At one time, basic research on the detection of objects and discriminations of their shapes and configurations was restricted to luminance-defined form. However, recent findings indicate that rather than containing only one subsystem for the early processing of the spatial attributes of objects, the visual system contains five parallel subsystems, the performances of three of which compare well with that for luminance-defined form, except only for fine detail and sharp edges (reviewed in Ref. 4). In the second half of this article is discussed the implications of these findings for clinical psychophysics.