Masao Ohmi

Shape from shading in different frames of reference.

It has often been reported that, in the absence of information about the direction of illumination, people interpret surface convexities and concavities in accordance with the assumption that illumination comes from above. However, ‘above’ could mean with reference to gravity, the head or the retina. Yonas et al reported that four-year-old infants use the head more than gravity as the frame of reference in interpreting surface relief but that seven-year-olds make about equal use of the two frames of reference. The potency of these two frames of reference when acting separately and when pitted against each other was measured on adult subjects. For all subjects the ‘assumption’ about the direction of illumination was predominantly with respect to the head. The gravitational frame was used only when the headcentric frame was irrevelant, and then not consistently.

Effects on visual functions during tasks of object handling in virtual environment with a head mounted display

This study examined the effects on visual functions of a prolonged handling task within the helmet-mounted display environment. Both version eye movement and accommodative response became gradually slower during the 40-min task. Although delayed presentation of display after head movement noticeably worsened both visual responses, presentation delay after hand movement did not significantly change the sluggishness of responses. Therefore it is suggested that decreasing time delay after head movement is a more important factor in order to improve human performance of handling tasks within the HMD environment.

The effect of central and peripheral field stimulation on the rise time and gain of human optokinetic nystagmus

We wished to examine the spatial (gain) and temporal (rise time) properties of human optokinetic nystagmus (OKN) as a function of stimulus velocity and field location. Stimuli were either M-scaled random dots or vertical stripes that moved at velocities between 20–80 deg s−1. Three field conditions were examined: full field; a 20 deg central field; and a 12.5 deg central-field mask. OKN gain was found to be significantly affected by stimulus velocity and stimulus location, with the higher stimulus velocities and the 12.5 deg central-field mask giving lower gains. Steady-state gains for all three field conditions were not found to be affected by prior adaptation to stationary or moving stimuli. The 63% rise time was found to be significantly affected by the stimulus velocity, whereas this was not the case for the 90% rise time. Neither rise time was found to be significantly affected by the field location. These results indicate that, although the effectiveness (gain) of peripheral retina is lower than that of the central retina during optokinetic stimulation, the peripheral retina has access to common mechanisms responsible for the fast component of OKN.

Localization of monocular stimuli in different depth planes

We examined the phenomenon in which two physically aligned monocular stimuli appear to be non-collinear when each of them is located in binocular regions that are at different depth planes. Using monocular bars embedded in binocular random-dot areas that are at different depths, we manipulated properties of the binocular areas and examined their effect on the perceived direction and depth of the monocular stimuli. Results showed that (1) the relative visual direction and perceived depth of the monocular bars depended on the binocular disparity and the dot density of the binocular areas, and (2) the visual direction, but not the depth, depended on the width of the binocular regions. These results are consistent with the hypothesis that monocular stimuli are treated by the visual system as binocular stimuli that have acquired the properties of their binocular surrounds. Moreover, partial correlation analysis suggests that the visual system utilizes both the disparity information of the binocular areas and the perceived depth of the monocular bars in determining the relative visual direction of the bars.

Gaze orientation during full-field and peripheral field passive optokinesis

During full‐field optokinetic nystagmus the mean position of gaze shifts the eyes in the direction of the fast phase. The driving force for this, pre‐supposes that the preferred locus for the position control system, is shifting gaze into the direction where the motion is coming from. In this study, six subjects were examined to determine whether the absence of the central visual field would influence the mean position of gaze during passive optokinesis. Our findings indicate that a full field and a central field restricted to 20 deg, evoked gaze shifts of up to 7 deg into the direction of the fast phase. However, when the central field was masked by either 12.5 deg or 25 deg the mean gaze position was found to be significantly reduced (p<0.05). This effect was not influenced by the velocity of the stimulus (p>0.05). These results lead us to conclude that gaze orientation during optokinesis is strongly influenced by the area of retina stimulated. The role of the slow eye movement control system and possible cognitive strategies adopted during selective spatial attention are discussed in the light of this finding.

How to Find a Recipe for Success of Popular Smart Phone Applications

The number of smartphone appliances is increasing rapidly. However, it is divided into a popular application and an application not so popular. There must be some recipe for success in the application that is gaining popularity and continuously using by customers.