Masumi Takada

Effect of Accommodation Training on Visual Function of Visual Inspection Workers and Middle-Aged People

By relaxing the contracted focus-adjustment muscles around the eyeball, such as the ciliary and extraocular muscles, improvement of the pseudo-myopia is expected. This understanding has led to the accommodation training in which the visual target is given by stereoscopic video clips. In this study, we verify short-term effects of the apparatus on eyesight of visual inspection workers (22 females) suffering from eye fatigue and 12 middle-aged persons. In the Measurement 1, the workers were trained in 3 days. Moreover, the middle-aged were investigated on several trials of the eyesight recovering apparatus in the Measurement 2. As a result, the visual acuity was statistically improved by continuous accommodation training which will promote a ciliary muscle-stretching effect.

Comparison in degree of the motion sickness induced by a 3-D movie on an LCD and an HMD

Three-dimensional (3D) television sets are already on the market and are becoming increasingly popular among consumers. Watching stereoscopic 3D movies, though, can produce certain adverse affects such as asthenopia and motion sickness. Visually induced motion sickness (VIMS) is considered to be caused by an increase in visual-vestibular sensory conflict while viewing stereoscopic images. VIMS can be analyzed both psychologically and physiologically. According to our findings reported at the last HCI International conference, VIMS could be detected with the total locus length and sparse density, which were used as analytical indices of stabilograms. In the present study, we aim to analyze the severity of motion sickness induced by viewing conventional 3D movies on a liquid crystal display (LCD) compared to that induced by viewing these movies on a head-mounted display (HMD). We quantitatively measured the body sway in a resting state and during exposure to a conventional 3D movie on an LCD and HMD. Subjects maintained the Romberg posture during the recording of stabilograms at a sampling frequency of 20 Hz. The simulator sickness questionnaire (SSQ) was completed before and immediately after exposure. Statistical analyses were applied to the SSQ subscores and to the abovementioned indices (total locus length and sparse density) for the stabilograms. Friedman tests showed the main effects in the indices for the stabilograms. Multiple comparisons revealed that viewing the 3D movie on the HMD significantly affected the body sway, despite a large visual distance.

Changes in Brain Blood Flow by the Use of 2D/3D Games

Recently, with the rapid progress in image processing and three-dimensional (3D) technology, stereoscopic images are not only seen on television but also in theaters, on game machines, etc. However, symptoms such as eye fatigue and 3D sickness may be experienced when viewing 3D films on displays and visual environments. The influence of stereoscopic vision on the human body has been insufficiently understood; therefore, it is important to consider the safety of viewing virtual 3D content. In this study, we examine whether exposure to 3D video clips affects the human body such as brain blood flow. Subjects viewed 3D video clips on the display of portable game machines, and time series data of their brain blood flow was measured by near-infrared spectroscopy (NIRS) with use of FOIRE-3000 (Shimazu Co. Ltd., Kyoto). Our results showed oxyhemoglobin tended to increase throughout the cerebral cortex while operating the game machines on the 3D display in comparison with the 2D display.

Subjective evaluation of peripheral viewing during exposure to a 2D/3D video clip

Symptoms of three-dimensional (3D) sickness, such as intoxication and eye fatigue, have been observed in subjects viewing 3D films and vary according to the image quality and visual environment. In addition, the influence of stereoscopic vision on the incidence of 3D sickness has not been explored sufficiently. Therefore, it is important to examine the safety of viewing virtual 3D content. The present study examines the effects of peripheral vision on reported motion sickness during exposure to 2D/3D video clips for 1 minute and for 1 minute afterwards in human subjects. The Simulator Sickness Questionnaire was administered after exposure to the video clips with or without visual pursuit of a 3D object and compared. The questionnaire findings significantly changed after the subjects viewed the video clips peripherally. This influence may result when subjects view a poorly depicted background element peripherally, which generates depth perception that contradicts daily experience.

Consideration of Indices to Evaluate Age-Related Muscle Performance by Using Surface Electromyography

Recently, there has been an increasing focus on the rapid reduction of muscles that are required for the bending of the hip joint during walking (flexor muscles around the hip joint) with age. The flexor muscles around the hip joint include femoral rectus and abdominal muscles. These muscles have been implicated in falling in the elderly people. In this study, we examined the smoothed surface electromyography (sEMG) of femoral rectus muscles during biofeedback training (BFT) of the dominant leg. To this end, we developed parameters for the measurement of shapes in the smoothed sEMG, and evaluated the changes in these parameters in the muscles with age. Reduction of the muscular regulation capacity due to aging can be detected by performing sEMG during BFT by using a parameter in the muscles.

Evaluating indices of age-related muscle performance by using surface electromyography

Recently, there has been an increasing focus on the rapid reduction of muscles that are required for the bending of the hip joint during walking (flexor muscles around the hip joint) with age. The flexor muscles around the hip joint include femoral rectus and abdominal muscles. These muscles have been implicated in falling in the elderly. In this study, we examined the smoothed surface electromyography (sEMG) of femoral rectus muscles during biofeedback training (BFT) of the dominant leg. To this end, we developed parameters for the measurement of shapes in the smoothed sEMG, and evaluated the changes in these parameters in the muscles with age. Statistical analysis indicated that it was necessary to include the time constant of the exponential decay curve fit to maximal points during prolonged muscular contraction, to evaluate the changes with age by using the smoothed sEMG during BFT. Reduction of the muscular regulation capacity due to aging can be detected by performing sEMG during BFT by using the time constant.

Measurement of Lens Focus Adjustment While Wearing a See-Through Head-Mounted Display

In recent years, many visual devices have been produced for consumers. The development of see-through smart glasses has attracted much attention. These glasses overlap virtually images by using Augmented Reality (AR) technology. Epson released the BT-2000 see-through smart glasses, which change distance of display by changing convergence. It is not confirmed that changing distance of display allow to change distance of lends accommodation. In this experiment, we measured lens accommodation of subjects viewing images displayed on see-through smart glasses. The results found that lens accommodation moved with the image position for over one hundred people. Therefore, our study verified that correct reaction occurred visual physiologically.

Analysis of the Body Sway While/After Viewing Visual Target Movement Synchronized with Background Motion

Stereoscopic imaging techniques have also become used for not only amusement but also in the industrial, medical care, and educational fields, however, symptoms due to the stereopsis have been reported. In this study, we especially focus on the effect of background motions on the equilibrium function. The body sway was recorded while/after viewing a sphere as a visual target synchronized/unsynchronized with periodic motion of the view point. Statistical analysis was conducted for the stabilograms.

Analysis of Electrogastrograms During Exercise Loads

A percutaneous electrogastrogram (EGG) is a simple and low-restraint way to measure the electrical activity of the gastrointestinal tract. An electrogastrogram examination is a noninvasive method of evaluating gastrointestinal motility and autonomic nervous system activity. However, EGGs are not as widely used in clinical settings as electrocardiograms (ECGs) or electroencephalographs (EEGs) because an EGG can be impacted by electrical activity from the myocardium and diaphragm (due to respiration), and there is no method to relate the functions of the stomach to the data obtained. This paper examines the effect of exercise on gastric electrical activity using two exercise intensities to confirm the basic biological response of an EGG. It was found that after high-intensity exercising the spectrum density at the normal frequency band of the stomach (2.4–3.7 cpm) decreased, which may indicate a decline in gastric activity during exercise. Exercise intensity is thought to affect the electrical activity of not only the gastrointestinal tract but also other organs.

Hygiene in Sleep: Problems of Sleeping Habits in Shift Workers: ―交替勤務者の睡眠習慣の課題―

Since World War II, Japan has achieved remarkable economic development and has become an advanced country. Particularly in the industrial field, a production system has been developed to reduce the loss of machining time by adopting a shiftwork in factories operating 24 hours a day, which contributes to the improvement of productivity. Nowadays, this shiftwork practice has spread from the industrial field to other businesses such as 24-hour entertainment facilities and convenience stores, which lead to sleep deprivation in Japanese society. Even at home, certain conditions adversely affect sleeping habits. We are concerned about the risks of physical and mental health, impairments posed by the use of tablets, PCs, smartphones, and other devices so popular in todays Japan, as they delay sleep. It is urgent to improve poor sleeping habits because their outcomes such as sleep disorders and deprivation may also lead to traffic and industrial accidents.