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It is physiologically known that the vestibular system and the autonomic nervous system interact with each other. The motion sickness can affect both these systems, and severity of the motion sickness is expected to be measured by dysfunction of the equilibrium system. We have proposed a new index, sparse density (SPD), of stationary stabilograms for detecting the metamorphism in the (temporally averaged) potential function of stochastic differential equations, which occurs when a human attempts to maintain an upright posture. It is known that a mathematical model of the body sway can be developed by a stochastic process. The authors have succeeded in finding the nonlinearity in the potential function. Subjects in a standing position were stimulated by a movie scrolling from left to right on a liquid crystal display (LCD) in measurement 1 and a stereoscopic video clip on an LCD in measurement 2. As a result, the dynamics of the body sway in the presence of the stimulus as well as in its absence were considered to be stochastic. The metamorphism in the potential function during exposure to blurred images and a stereoscopic video clip could be detected by using the SPD.

Visually induced motion sickness (VIMS) is known to be caused by sensory conflict, which is the disagreement between vergence and visual accommodation while observing stereoscopic images. The simulator sickness questionnaire (SSQ) is a well-known method that is used herein for verifying the occurrence of VIMS. We quantitatively measure the sway of the centre of gravity of the human body before and during exposure to several images. During the measurement, subjects are instructed to maintain the Romberg posture for the first 60 s and a wide stance (midlines of the heels 20 cm apart) for the next 60 s. The stereoscopic images decrease the gradient of the potential function involved in the stochastic differential equations as a mathematical model of the body sway. We have succeeded in estimating the decrease in the gradient by using an index called sparse density.

In the present study, we examined the visual accommodation of subjects who were gazing fixedly at 3D images from two different displays: a cathode ray tube (CRT) while wearing special glasses and a liquid crystal display (LCD) while not wearing special glasses. The subjects in this experiment were two healthy people aged 22 and 39 years, all with normal vision. The instrument objectively measured visual accommodative changes of the right eye in both binocular and natural viewing conditions. The results suggested that it was easy and comfortable to focus on both the LCD and CRT. When the subjects viewed the progressively receding target, their accommodation was about 0.8 D at the presumed furthest points, a level at which the ciliary muscle is relaxed. The accommodative power differed by about 1.5 D from the near to far point. Thus, the ciliary muscle is repeatedly strained and relaxed while the subject views the moving target.

The viewers of three-dimensional (3D) movies often complain of blurring and bleeding. They sometimes experience visually induced motion sickness (VIMS). In this study, the effect of VIMS on body sway was examined using stabilograms. We measured the sway in the center of gravity before and during the exposure to images projected on a head-mounted display (HMD). While viewing, the subjects were instructed to remain in the Romberg posture for the first 60 seconds and maintain a wide stance (midline of the heels, 20 cm apart) for the next 60 seconds. Employing Double-Wayland algorithm, we measured the degree of determinism in the dynamics of the sway in the center of gravity with respect to viewing 3D movies on HMD. As a result, the dynamics of the sway during and before the exposure was considered to be stochastic. Thus, exposure to 3D movies would not change the dynamics to a deterministic one.

The purpose of this study was to clarify the effect on visual function of gazing at stereoscopic images on a head mounted display (HMD). We measured visual accommodation during stereoscopic viewing while using a HMD by using our original instrument of measurement. The presented image was shown 3-dimensionally on an HMD set up at a visual distance of 3 cm. A spherical object moved back and forth toward and away from the observer in a 10 sec cycle. While the subjects were gazing at the 3D image with both eyes, the lens accommodation in the right eye was measured and recorded. Accommodation to the virtual objects was shown during the viewing of stereoscopic images of 3D computer graphics, but was not shown when the images were displayed without appropriate binocular parallax. It is suggested that stereoscopic moving images on HMD induced the visual accommodation by the expansion and contraction of the ciliary muscle, which is synchronizing with convergence.

Often, people travelling in ships, trains, aircraft, and cars tend to experience motion sickness. It has been reported that even users of virtual environments and entertainment systems experience motion sickness. This visually induced motion sickness (VIMS) is known to be caused by sensory conflict, which is the disagreement between vergence and visual accommodation while observing stereoscopic images. VIMS can be measured by psychological and physiological methods. The simulator sickness questionnaire (SSQ) is a well-known method that is used herein for verifying the occurrence of VIMS. We also quantitatively measure the sway of the centre of gravity of the human body before and during exposure to several types of movies. During the measurement, subjects are instructed to maintain the Romberg posture for the first 60 s and a wide stance (with midlines of the heels 20 cm apart) for the next 60 s. The centre of gravity is projected on a plane that is parallel to the ground. The body sway is recorded as a stabilogram on the plane. According to previous research, a stochastic process is regarded as a mathematical model that generates stabilograms. We propose a method to obtain stochastic differential equations (SDEs) as a mathematical model of the body sway on the basis of the stabilogram. While there are several minimal points of the temporally averaged potential function involved in the SDEs, the stereoscopic images decrease the gradient of the potential function. We have succeeded in estimating the decrease in the gradient of the potential function by using an index called sparse density.

A multilingual disaster information system (MLDI) has been developed to overcome the language barrier during times of natural disaster. MLDI is a webbased system that includes templates in nine languages so that translated texts can be made available immediately. Mobile phone e-mail with graphic text is a useful tool for delivering multilingual disaster information. We assessed the performance of the translation system and the multilingual graphical characters, and found that they are sufficiently useable. We discussed the usage of mobile phones for multilingual disaster information delivery system including Early Earthquake Warning system. Multilingual mobile information and measures is useful for a safe and barrier-free society.

Subject performance in reading characters on mobile phone liquid crystal displays was researched with the use of: (1) sentences without meaning, made from randomly ordered alphanumeric characters having 3 different sizes of characters and 4 different contrasts (n=78; age=39.9±17.6), (2) Japanese characters of 5 different sizes and 2 types of font (n=98; age=44.5±18.5), and (3) Japanese characters vertically enlarged 1-4 times (n=120; age=46.9±18.6). Readability was higher with higher contrast displays, and with Gothic than with Mincho font in Japanese. Readability of Japanese characters improved when they were vertically enlarged to approximately twice the width.

An experiment was conducted on the ease with which a car navigation system could be read by elderly, middle-aged and young people. 127 subjects (19-76 years of age) evaluated ease of reading of the displayed characters. The experiment evaluated characters displayed on a liquid crystal display (LCD) similar to those used in car navigation systems, and evaluated readability in 9 stages. Five character sizes for traffic terms and two languages (Japanese and English) were used in the experiment. The experiment was conducted with the LCD in 2 positions: directly in front of the subject and diagonal to the left (about 30 degrees). The results showed that the directly frontward position was significantly more readable than the position of diagonal to the left.

The purpose of this study was to examine the relationships between the visibility of mobile phone displays and aging effects on subjects' visual functions, based on measurements of vision, including near visual acuity and cataract cloudiness. In the relation between Character size, CC, and NVA, visibility was lower with smaller character size "S". In the relation between Contrast, CC, and NVA, the organoleptic evaluations showed significant differences in contrast. The subjects' attached a high value to the negative display mode, especially when the subject's CC was more than 200. Such considerations are particularly important for elderly users who have marked deterioration of visual function.