Discomfort due to glare from a large source: Evaluating stimulus range effects when using the luminance adjustment procedure

Using the luminance adjustment procedure, we evaluated four discomfort sensation on a Hopkinson-like glare scale: (a), (b), (c) and (d), respectively. Two methodological factors that were beleived to influence the luminance adjustment procedure were investigated. One was the stimulus range bias effect. This describes how the influence of the available range of a variable stimulus (i.e., glare source luminances) influence the setting made to a subjective sensation (i.e., \"just uncomfortable\" glare). 42 test participants were recruited to the experiment and made glare settings to four the discomfort sensations under three stimulus ranges with difference maximum luminances: low, middle, and high. Adjustments were performed to the luminance of a large articial window backlit by an array of warm and cool LEDs. This was repeated for two methods of control. Direct: with the obsever making adjustments directly to the glare source to the four discomfort sensations; and Indirect: with the experim...