USER EVALUATIONS OF CONTRAST-DOMINANT DISCOMFORT GLARE IN DIM DAYLIT SCENARIOS: PRELIMINARY FINDINGS

Discomfort glare metrics typically consider at least one of the two effects of discomfort glare - saturation and contrast - in their equation. The former occurs when there is an excessively bright glare source in the field of view, while the latter occurs when there is a high luminance ratio between the glare source and the adaptation level of the eye. We hypothesize that the contrast effect may dominate in low-light scenarios such as those commonly found in open-plan offices. Thus, we designed and carried out a user study in controlled laboratory conditions with 63 participants with a total of 252 scenes to investigate discomfort glare evaluations in dim daylight office environments with low adaptation levels. Our preliminary findings support our hypothesis that contrast-driven metrics predict glare responses in a more reliable way than hybrid metrics at low adaptation levels where the contrast effect dominates, which underlines the need for refining glare metrics in low brightness conditions.

EVALUATION STRUCTURE ON PREFERENCE OF PAINTING’S APPEARANCE WITH LOW REFLECTANCE IN THE MUSEUM LIGHTING ENVIRONMENT

The purpose of this paper is to clarify the evaluation structure of the preference for the visibility of paintings, taking into account the characteristics of paintings with low reflectance. Although illuminance is used in the standards for museum lighting (CIE 157:2004), it is desirable to design lighting that also considers luminance from the viewpoint of perceived brightness. Therefore, we conducted the subjective experiment of oil paintings in which luminance ratio was set as an experimental variable and examined the evaluation structure of paintings with low reflectance. As a result, it was found that the evaluation of black details affects the preference for the visibility of paintings with low reflectance. However, the path diagram of the evaluation structure applied to each painting was different, indicating that it is difficult to represent the characteristics of a painting only by the mean reflectance.

Characterizing approach behavior of Drosophila melanogaster in Buridan’s paradigm

The Buridan’s paradigm is a behavioral task designed for testing visuomotor responses or phototaxis in fruit fly Drosophila melanogaster. In the task, a wing-shortened fruit fly freely moves on a round platform surrounded by a 360° white screen with two vertical black stripes placed at 0° and 180°. A normal fly will tend to approach the stripes one at a time and move back and forth between them. A variety of tasks developed based on the Buridan’s paradigm were designed to test other cognitive functions such as visual spatial memory. Although the movement patterns and the behavioral preferences of the flies in the Buridan’s or similar tasks have been extensively studies a few decades ago, the protocol and experimental settings are markedly different from what are used today. We revisited the Buridan’s paradigm and systematically investigated the approach behavior of fruit flies under different stimulus settings. While early studies revealed an edge-fixation behavior for a wide stripe in the initial visuomotor responses, we did not discover such tendency in the Buridan’s paradigm when observing a longer-term behavior up to minutes, a memory-task relevant time scale. Instead, we observed robust negative photoaxis in which the flies approached the central part of the dark stripes of all sizes. In addition, we found that stripes of 20°-30° width yielded the best performance of approach. We further varied the luminance of the stripes and the background screen, and discovered that the performance depended on the luminance ratio between the stripes and the screen. Our study provided useful information for designing and optimizing the Buridan’s paradigm and other behavioral tasks that utilize the approach behavior.

Changes of mind and absolute evidence

To navigate the world safely, we often need to rapidly ‘change our mind’ about decisions. Current models assume that initial decisions and change-of-mind decisions draw upon common sources of sensory evidence. In two-choice scenarios, this evidence may be ‘relative’ or ‘absolute’. For example, when judging which of two objects is the brightest, the luminance difference and luminance ratio between the two objects are sources of ‘relative’ evidence, which are invariant across additive and multiplicative luminance changes. Conversely, the overall luminance of the two objects combined is a source of ‘absolute’ evidence, which necessarily varies across symmetric luminance manipulations. Previous studies have shown that initial decisions are sensitive to both relative and absolute evidence; however, it is unknown whether change-of-mind decisions are sensitive to absolute evidence. Here, we investigated this question across two experiments. In each experiment participants indicated which of two flickering greyscale squares was brightest. Following an initial decision, the stimuli remained on screen for a brief period and participants could change their response. To investigate the effect of absolute evidence, the overall luminance of the two squares was varied whilst either the luminance difference (Experiment 1) or luminance ratio (Experiment 2) was held constant. In both experiments we found that increases in absolute evidence led to faster, less accurate initial responses and slower changes of mind. Change-of-mind accuracy decreased when the luminance difference was held constant, but remained unchanged when the luminance ratio was fixed. The initial response effects could be explained by the presence of input-dependent noise within the decision process, varying either within or across trials. However, the change-of-mind effects could not be captured by existing models, nor by two modified models which included input-dependent noise sources. This suggests that that the continued integration of sensory evidence following an initial decision operates differently to that described in existing theoretical accounts.