Search

The global virtual reality (VR) market is significantly expanding and being challenged with an increased demand owing to COVID-19. Unfortunately, VR is not useful for everyone due to large interindividual variability existing in VR suitability. To understand the neurobiological basis of this variability, we obtained neural structural and functional data from the participants using 3T magnetic resonance imaging. The participants completed one of two tasks (sports training or cognitive task) using VR, which differed in the time scale (months/minutes) and domain (motor learning/attention task). Behavioral results showed that some participants improved their motor skills in the real world after 1-month training in the virtual space or obtained high scores in the 3D attention task (high suitability for VR), whereas others did not (low suitability for VR). Brain structure analysis revealed that the structural properties of the superior and inferior parietal lobes contain information that can predict an individual’s suitability for VR.

Temporal characteristics of depth perception from motion parallax were examined by modulating parallax intermittently while observers moved their head side to side. In Experiment 1, parallax of a fixed value was introduced only for the central 1/6 to 5/6 portion of each component head movement. It was found that the perceived depth was proportional to the temporal average of parallax-specified depth. In addition, observers did not notice any abrupt temporal change of depth. In Experiment 2, parallax was increased or decreased once per trial either at the center or the end of one of the component head movements, and observers judged the direction of depth change. Again, observers did not notice any abrupt change of depth. The percentage of correct responses was almost constant for large change amplitudes. Reaction times to the change were over 1 s even for the largest changes, and it increased for smaller change amplitudes. These results indicate that the mechanism for depth from parallax has a configuration similar to that proposed for structure from motion, and that it involves a temporal integration process with a relatively long time-constant.

A person depicted in portrait paintings does not appear slanted even when observers move around. The gaze is also fixed to the observer. This constancy in angle of face/body orientation or gaze direction is called the Mona Lisa effect. Do observers realize the portrait was physically slanted when the effect occurs? What is the relationship between the effect for face/body and gaze? To answer these questions, we separately measured the perceived angle of face, gaze, and background while varying the physical slant of portrait itself. The stimulus was a computer generated face (19 × 12 deg) presented on a 3D LCD display. It was surrounded by a 24 × 24 deg black-contour frame filled with a noise texture. There were also no-frame and/or no-texture conditions. The slant was varied between ±30 deg. The observer was asked to judge the direction of gaze and the orientation of face or background in separate sessions. It was found that the perceived gaze almost always directed toward the observer regardless of slant angle or existence of frame or background. In contrast, the face orientation was judged facing the observer only in 40–50% of trials, and it was facing at the correct angle in 50–60% of trials. The background was perceived correctly in most trials. These results demonstrate special characteristics of eyes. The gaze is always directed to you even when the portrait is slanted and the background is perceived slanted. The face has intermediate characteristics: it is sometimes directed to you, but sometimes it appears slanted.