After-effects of TFT-LCD display polarity and display colour on the detection of low-contrast objects

Abstract

Participants performed a word-non-word discrimination task within a car control display emulated on a thin film transistor liquid-crystal display (TFT-LCD). The task simulated an information read-out from a TFT-LCD-based instrument panel. Subsequently, participants performed a low-contrast object detection task that simulated the detection of objects during night-time driving. In experiment 1, words/non-words were presented black-on-white (positive polarity) or white-on-black (negative polarity). In experiments 2 and 3, display colour was additionally manipulated. A positive polarity advantage in the discrimination task was consistently observed. In contrast, positive displays interfered more than negative displays with subsequent detection. The detrimental after-effect of positive polarity displays was strong with white and blue, reduced with amber and absent with red displays. Subjective measures showed a preference for blue over red, but a slight advantage for amber over blue. Implications for TFT-LCD design are derived from the results. STATEMENT OF RELEVANCE: When using TFT-LCDs as car instrument panels, positive polarity red TFT-LCDs are very likely to lead to good instrument readability while at the same time minimising - relative to other colours - the negative effects of an illuminated display on low-contrast object detection during night-time driving.

Positive Display Polarity Is Particularly Advantageous for Small Character Sizes

“…The results of the present study show a typical positive polarity advantage in terms of better proofreading performance for text presented in dark characters on light background (positive polarity) than for text presented in light characters on dark background (negative polarity). This finding is in line with previous research (e.g., Bauer & Cavonius, 1980; Buchner & Baumgartner, 2007; Chan & Lee, 2005; Mayr & Buchner, 2010; Piepenbrock et al, 2013; Taptagaporn & Saito, 1990, 1993). The same is true for the finding that larger character sizes improved text legibility leading to better proofreading performance and higher reading speed (cf., Bernard et al, 2003; Fagan et al, 1986; Griffing & Franz, 1896; Luckiesh & Moss, 1939; Miyao et al, 1989; S.…”

“…When driving at night, light emitted by displays in a car reduces the dark adaptation of the driver's eyes, thereby reducing the driver's sensitivity to low-contrast objects on, or on their way to, the road. Positive polarity displays should therefore lead to a larger sensitivity reduction for such objects than negative polarity displays, and this is in fact the case (Mayr & Buchner, 2010). A possible solution may be to use red instead of white as the background color because the cones in the human retina are mostly insensitive to the red light emitted by typical thin film transistor-LCD displays.…”

“…Several authors reported better legibility of a positive display polarity as compared with a negative one. For instance, a positive polarity advantage was demonstrated in terms of lower error rates and response times in letter identification (Bauer & Cavonius, 1980), faster transcription of displayed letters (Radl, 1980), faster reading performance (Chan & Lee, 2005), better proofreading performance (Buchner & Baumgartner, 2007; Piepenbrock, Mayr, Mund, & Buchner, 2013), better word–nonword discrimination (Mayr & Buchner, 2010), increased visual acuity (Piepenbrock et al, 2013), and higher visual comfort (Taptagaporn & Saito, 1990, 1993). Findings of no positive polarity advantage have also been reported.…”

“…However, these findings may have been the result of low statistical power (e.g., Legge et al, 1985, with n = 6; Legge et al, 1987, with n = 2) and the use of flicker-prone cathode ray tube monitors (e.g., Creed et al, 1988; Cushman, 1986; Gould et al, 1987; Pastoor, 1990; A. H. Wang & Chen, 2000; for details, see Mayr & Buchner, 2010). A negative polarity advantage does not seem to have been reported to date for observers with normal vision such that the pattern of results suggests that the positive polarity advantage can be considered as real.…”

Effect of display polarity and luminance contrast on visual lobe shape characteristics

“…The other is negative polarity which refers to the condition where light characters are displayed on a dark background. Generally, positive display polarity reduces optical distortion and enhances contrast sensitivity, depth of field, speed of lens accommodation, visual discrimination, and visual identification of motion (Bauer and Cavonius 1980, Feng, et al 2008, Mayr and Buchner 2010. Positive polarity displays were rated higher than negative ones when visual acuity and luminance contrast were considered important for a task (Bergqvist 1984), and when pupil and lens accommodation were tested (Saito et al 1989).…”