Trait-based individual differences on discomfort glare rating responses and related visual contrast sensitivity

Abstract

and Related Visual Contrast Sensitivity Haruetai Mekaroonreung (ABSTRACT) This research was designed to investigate the relationship between Trait-based Individual differences (neuroticism and extraversion) and glare subjective responses as well as the actual contrast sensitivity when exposed to the same manipulated glare condition. In addition, the relationship between the glare subjective responses and actual contrast sensitivity was investigated. To examine the trait-based individual differences, the International Personality Item Pool (IPIP) was used while the subjective glare experience was examined utilizing modified glare discomfort rating scale. The visual performance was measured through the contrast sensitivity level using adjustable contrast level of the Landolt's C target. This investigation compared 36 individuals (9 high neuroticism scorers, 9 low neuroticism scorers, 9 high extraversion scorers, and 9 low extraversion scorers) on subjective discomfort glare rating responses and visual contrast sensitivity. The study is directed toward improving our understanding of influencing factors on the experience of discomfort glare, which may eventually be applied to the design of glare measurement methods, and toward training and selection of drivers and workers who may work under conditions of glare. Results indicated significant effect of extraversion trait on rating response while insignificant effect on visual related performance was found. The relationships between rating response and visual performance were also found to be quite low in this study. In conclusion, the expected model was supported but only on the extraversion trait. RationaleFeelings of discomfort glare have been widely assessed with rating scales for various purposes, especially in the design of lighting configurations such as street lighting and visual display terminal (VDT) systems. However, consensus is lacking among researchers in terms of discomfort glare assessment methods (Gellatly and Weintraub, 1990;Lennie & Van Hemel, 2002;Olson & Sivak, 1984;Sivak & Flannagan, 1994). Although the between-subject variations in rating scores are repeatedly reported to be quite high, the subjective glare rating has been the method used for many years.Several subjective rating scales have been proposed since the 1960s (De Boer, 1967a).Among these rating scales, the 9 point De Boer scale is most often used in the field of automotive and public lighting systems (Theeuwes, 2002) while some other scales such as Visual Analog Scale (VAS) are used less frequently.As suggested by few researchers (Berman et al., 1994;Theeuwes, 2002), one underlying reason for the large variability of this subjective response could be the result of differences in the observers' trait rather than visual impairment. For example, people with dispositions related to worry or anxiety may have a perceived criterion for discomfort that is much lower than those who have dispositions that are less anxiety or worry prone. As a result, the worried people could exhibit more...