Assessing the temporal uniformity of CIELAB hue angle.

In recent work [J. Opt. Soc.

Perceived speed of changing color in chroma and hue directions in CIELAB.

In dynamic LED lighting, the perceived speed of changing color is an important concept; however, there exists no suitable temporal color space. In a psychophysical experiment, we compared the perceived speed of periodic temporal transitions in CIELAB chroma and hue directions around five base colors [the five Munsell hues: 5R (red), 5Y (yellow), 5G (green), 5B (blue), and 5P (purple)]. The experiment was conducted in a light laboratory, with the main illumination stimulus subtending a visual angle of 101×77  deg.

Investigation of Dose-Response Relationships for Effects of White Light Exposure on Correlates of Alertness and Executive Control during Regular Daytime Working Hours.

To date, it is largely unknown which light settings define the optimum to steer alertness and cognitive control during regular daytime working hours. In the current article, we used a multimeasure approach combined with a relatively large sample size ( N = 60) and a large range of intensity levels (20-2000 lux at eye level) to investigate the dose-dependent relationship between light and correlates of alertness and executive control during regular working hours in the morning and afternoon. Each participant was exposed to a single-intensity light level for 1 h after a 30-min baseline phase (100 lux at the eye) in the morning and afternoon (on separate days) during their daily routine.

Spatio-chromatic sensitivity explained by post-receptoral contrast.

We measured and modeled visibility thresholds of spatial chromatic sine-wave gratings at isoluminance. In two experiments we manipulated the base color, direction of chromatic modulation, spatial frequency, the number of cycles in the grating, and grating orientation. In Experiment 1 (18 participants) we studied four chromatic modulation directions around three base colors, for spatial frequencies 0.

Stroboscopic effect: contrast threshold function and dependence on illumination level.

The stroboscopic visibility measure (SVM) is a method used to quantify the stroboscopic effect visibility in general illumination application. SVM has been defined previously based on a limited number of frequencies and participants. To validate and extend SVM, five perception experiments are presented, measuring the visibility threshold of light waveforms modulated at several frequencies, conducted in two different labs.

The effect of spatial luminance distribution on dark adaptation.

Recent studies show that dark adaptation in the visual system depends on local luminance levels surrounding the viewing direction. These studies, however, do not explain to what extent veiling luminance is responsible for the outcome. To address the latter, in this study dark adaptation was measured for three different spatial luminance distributions surrounding a target to be detected, while keeping the veiling luminance at the location of the target equivalent.

Detection of temporal delays in visual-haptic interfaces.

This paper addresses the question of how large the temporal delay between a visual and a haptic stimulus may be such that the stimuli are still perceived as being synchronous. Participants had to judge whether the moment at which a graphical object collided with a virtual wall occurred simultaneously with the moment at which a force was felt through a force feedback joystick. Participants either moved the joystick to drive the object (active touch) or held the joystick in a steady position while the object moved by itself (passive touch).