Effects of color-tinted lenses on visual behavior

Abstract

The ability to perceive light as different colors strongly impacts our daily behavior and is associated with visual performance and emotions. Color perception can be modified with light filters, also called color-tinted lenses, that form spectral patterns. The purpose of this thesis is to describe the effects of color-tinted lenses on visual behavior by assessing visual, optophysiological, and emotional performance. Visual performance can be exemplarily determined psychophysically by contrast sensitivity tests. When focusing on near distances, optophysiological performance is reflected in the lag of accommodation, which can be modulated by progressive addition lenses. Emotional performance, as reflected in the arousal level under affective conditions, can be described by a late positive potential in the brain measured by electroencephalography. This thesis considers three approaches to investigate the effect of custom-designed and existing color-tinted lenses on different measurements of performance in human participants: contrast sensitivity, lag of accommodation, and visceral neurophysiology. First, to accurately evaluate the influence of color-tinted lenses on visual performance, a contrast sensitivity test was developed with higher precision, repeatability, and reliability than existing tests, called the Tuebingen Contrast Sensitivity Test. With this test, it was found that neither existing colortinted lenses nor high- and band-pass-filter color-tinted lenses significantly improved contrast sensitivity. Second, red-tinted lenses were able to reduce the lag of accommodation. Third, with red-tinted lenses, physiological measurements revealed a higher amplitude of the late positive potential and skin conductance after showing affective pictures, such as a smiling baby, an erotic couple, or a mutilated body. The color-tinted lenses investigated appear to affect opto-physiological and emotional performance, but not visual performance when compared to clear lenses. In future experiments, a potential common mechanism behind the two effects observed in optophysiological and emotional performance, namely, better lag of accommodation with red-tinted lenses and higher arousal level under emotional conditions, could be explored. In summary, this thesis shows that color-tinted lenses can change visual behavior.