Visual Fatigue and Spatial Frequency Adaptation to Video Displays of Text

Abstract

This article proposes that adaptation to the fundamental spatial frequency of lines of text on a video display terminal (VDT) provides a single explanation for a wide variety of reports of visual fatigue by VDT users. Reliable contrast threshold elevations at spatial frequencies of 2, 3, and 5 cycles/deg were found after subjects read single-spaced text on a VDT. This adaptation also reduces sensitivity to spatial frequencies in the range (2 to 6 cycles/deg) largely responsible for the reflexive accommodative response (Bour, 1981. Charman and Heron, 1979), and therefore could account for objective optometric measures of disturbed accommodation as well as some subjective effects of VDT viewing. Implications for video display design and for further research are discussed.

Near Work–Induced Contrast Adaptation in Emmetropic and Myopic Children

“…Based on the spatial frequency content of the adapting targets and literature, 13,18,27,29 we expected to see contrast adaptation around 6 cpd for the sine-wave grating 18,30 and around either the row (1.2 cpd) 31,32 or stroke frequency (6.0 cpd) for the text. The possibility that contrast adaptation was involved in myopia development led to the hypothesis that myopic children would show greater contrast adaptation than emmetropic children.…”

A spatial frequency account of the detriment that local processing of Navon letters has on face recognition.

“…In practice, this means the visual cortex can become adapted to, for example, high resolution images, causing an aftereffect in which it is easier to identify objects in low resolution images. An adaptation of three minutes will only affect a very narrow band of spatial frequencies (Menees, 1998, Webster & Mollon, 1999 such as causing visual fatigue for text on a computer screen (Lunn & Banks, 1986).…”

Measurement and Research issues in Teacher Assessment

“…Our development efforts in this respect focus on (a) familiarization materials; (b) the design of extremely simple user interfaces, screens, and sequences; and (c) understanding the cognitive demands presented by interacting with the computer. Research on computer screen reading speed (Lunn & Banks, 1986;Mills & Weldon, 1987), the graphic design of text on the computer screen (Kang & Muter, 1989), and user control of the computer's sequencing and other orientation functions (Wright & Lickorish, 1988) (Fischer, 1989;Heckel, 1983;Liddle, 1989;McDonald & Schvaneveldt, 1988) stressing the importance of the match between the user's mental models and the design of the computer-delivered materials guides development and future research.…”