Scientific
publications

We investigated the conjoint effect of screen luminance and ambient illuminance on visual fatigue and arousal during prolonged digital reading (one hour) by means of a multidimensional approach based on eye, performance and subjective measures. Two levels of screen luminance (low, high) and two levels of ambient illuminance (low, high) were tested in a 2 × 2 between-subjects design in which participants were arbitrarily allocated to four groups, one for each combined level of luminance and illuminance. Results showed that reading under high levels of screen luminance increases visual fatigue, as reflected by a decrease of eye blinks. Concerning arousal, exposure to higher levels of either luminance or illuminance increased alertness and performance. Faster saccades, increased reading speed and less microsaccades were found under high screen luminance. Fewer regressive saccades and shorter reaction times were observed under high ambient illuminance. However, the reason why some of these measures are sensitive to screen luminance while other to ambient illuminance remains unknown. These findings might have practical implications for the implementation of adaptive brightness solutions and for the online detection of both visual fatigue and arousal levels during digital reading.

This article proposes a method based on wavelet transform and neural networks for relating pupillary behavior to psychological stress. The proposed method was tested by recording pupil diameter and electrodermal activity during a simulated driving task. Self-report measures were also collected. Participants performed a baseline run with the driving task only, followed by three stress runs where they were required to perform the driving task along with sound alerts, the presence of two human evaluators, and both. Self-reports and pupil diameter successfully indexed stress manipulation, and significant correlations were found between these measures. However, electrodermal activity did not vary accordingly. After training, the four-way parallel neural network classifier could guess whether a given unknown pupil diameter signal came from one of the four experimental trials with 79.2% precision. The present study shows that pupil diameter signal has good discriminating power for stress detection.

Two main factors seem to contribute to the development of a riding configuration, and consequently of a motorcycle simulator: the trajectory control modality and the leaning rendering. The goal of this study was to compare two riding simulator configurations through the assessment of the underlying mental workload adopting a multidimensional approach based on psychophysiological, performance, and subjective measures. In the first configuration (reduced motion), the trajectory control is obtained by means of positive steering, while the leaning is produced just by tilting the visual scene. Like a real motorbike, the second configuration (dynamic) allows a progressive transition between positive and counter steering as the speed increases, whereas the leaning is rendered by splitting the rolling angle between the tilting of the visual scene and the rolling of the platform. Each participant completed six lane-change tasks per configuration, of which the first three and the last one were single tasks, and the remaining two were dual tasks. The occurrence of three single-task runs at the beginning of the experiment allowed us to examine the process of adaptation to each configuration, which is a critical precondition for simulator validity. The dynamic configuration proved to have higher validity, as confirmed by psychophysiological and subjective measures. Findings might have implications for the development of future riding simulators.