The modality appropriateness hypothesis argues that the auditory modality is preferred over the visual modality in tasks demanding temporal operations; hence, we predicted that responses to visual stimuli would be more sensitive to the detrimental effect of Time-on-Task. We used a bimodal temporal discrimination task. The factors were durational congruency between the modalities and the direction of modality-transmission. Participants needed to decide the duration of the cued stimulus (visual or auditory). The first five blocks of the task lasted about 1.5 h without rest [Time-on-Task (ToT) period]. The participants then had a 12-min break followed by an additional block of trials. Subjective fatigue, reaction time, error rates, and electrocardiographic data were recorded. In the visual modality, we found an enhanced congruency effect as a function of ToT. The cost of attentional shifting was higher in the auditory modality, but remained constant, suggesting that processing of auditory stimuli is robust against the effects of fatigue. Performance did not improve after the break, indicating that the effects of fatigue could not be overcome by taking a brief break. The heart rate variability (HRV) data showed that vagal inhibition increased with ToT, but this increase was not associated with the changes in performance.

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During virtual reality usage, two egocentric mental representations are constructed simultaneously. The first representation is rooted in the physical reality in which VR is set up, and the second originates from the mental construction of a computer-generated virtual environment. In both cases, participants configure their posture based on multimodal stimuli while responding to environmental cues. In most cases, the postural cues provided by the digital and real environment may be conflicting. In this study, 50 right-handed volunteers were enrolled. In a pre-test session, attentional focus-related personality bias (perspective-taking) was assessed, and afterward, postural movements and presence experiences were measured while the participants performed a spatial orientation task in VR. Participants were placed in an upright position with their right hands positioned in front of a physically real point on the laboratory wall. Afterward, participants were exposed to a VR environment in which they performed a room-tilting task. Participants with higher hand-related presence scores showed decreased compensatory hand drift in the VR environment. The rate of contralateral hand drift showed a reversed association with the intensity of the perspective-taking trait. VR-induced postural instability can be attenuated by the compensative hand drift that alleviates the conflicts between the two rival inner VR and outer VR environments that compete for attention and provide different reference cues.

IntroductionTo understand the nature of hemispatial attention allocation in virtual reality (VR), a line bisection task (LBT) was administered both in a real environment and a virtual environment to assess the rate of pseudoneglect. The mental construction of real and virtual environments was assumed to increase visuospatial activity in right hemisphere-related cognitive processes; an alteration in the activity that manifests in the direction and rate of line bisection lateral error.MethodsIn the present study, fifty-one right-handed healthy college students were recruited. They performed a line bisection task in real and virtual environments.ResultsThe obtained data showed that LBT errors in real and VR environments were correlated and individually consistent. Furthermore, a leftward LBT error was found in the physically real environment, however, in a VR the line bisection bias drifted towards the right hemispace. Participants with a lower right-handedness score showed a lower rate of left LBT bias in a real environment, but in VR, their LBT error showed a stronger rightwards error.DiscussionParticipants showed an individually consistent pattern in both real and VR environments, but VR-induced visuospatial reality construction was associated with rightward LBT bias in a virtual environment.