Tadahiko Fukuda

Visual search strategies of baseball batters: Eye movements during the preparatory phase of batting

The aim of this study was to analyze visual search strategies of baseball batters during the viewing period of the pitchers motion. The 18 subjects were 9 experts and 9 novices. While subjects viewed a videotape which, from a right-handed batters perspective, showed a pitcher throwing a series of 10 types of pitches, their eye movements were measured and analyzed. Novices moved their eyes faster than experts, and the distribution area of viewing points was also wider than that of the experts. The viewing duration of experts of the pitching arm was longer than those of novices during the last two pitching phases. These results indicate that experts set their visual pivot on the pitchers elbow and used peripheral vision properties to evaluate the pitchers motion and the ball trajectory.

Visual search strategies of soccer players in one-on-one defensive situations on the field.

This study analyzed visual search strategies of soccer players in one-on-one defensive situations on the field. The 8 subjects were 4 experts and 4 novices. While subjects tackled an offensive player for possession of the ball, their eye movements were measured and analyzed. Statistically significant differences between the visual search strategies of experts and novices showed experts fixated more often on both the knee and the hip regions of opponents than novices did. This suggests that information gained from the movements of these areas was important in anticipating an opponents next move. Findings suggest the importance in soccer for players not to focus too closely on the ball, but on an opponents knee and hip.

Glare from monitors measured with subjective scales and eye movements

Participants were confronted with four types of reflections on a computer screen, and the visual effects they experienced were recorded. The effects of non-glare, specular, diffuse and combined specular/diffuse reflexes were measured through eye movements, category scales and magnitude estimation. Two presentations, a picture and a text page were shown to the eight participants. The reflexes had no easily detectable effect on the eye movement variables, but had a significant effect on all the category scales. The specular reflex condition was always judged as the most disturbing. One eye movement variable, average velocity, had a significantly higher velocity for the picture. The eye movement variables and the category scales formed different factors in a factor analysis. Irritation appeared to be an important determing variable for the other scales.

Definition of gazing point for picture analysis and its applications

The authors have been analyzing images by eye movement. For this purpose, it is necessary to decompose the eye movement into a component to accept information from a gazed object and a component to shift the gazing point. The point considered in the foregoing is called the gazing point, which is defined in this paper based on the property of the pursuit eye movement. Eye movement velocity of 5 deg/s is used as the threshold to separate the two components. As a result, it is made possible to separate clearly the eye movement into the gazing point component and the shift between the gazing point. A vision analyzer based on this definition of the gazing point was developed, which can analyze comprehensively the eye movement in real-time. As an example of the application of the vision analyzer, the difference of the eye movement in watching the VDT image and the usual dynamic picture is analyzed. Furthermore, as an application to the analysis of art, an experiment was made as a reference material for the analysis of Sharakus ukiyo-e painting. The results of experiments are described, indicating that the definition of the gazing point is adequate.

Visual Behaviors of Soccer Players While Kicking with the inside of the Foot

This study analyzed the visual behaviors of soccer players while they kicked with the inside of the foot, which involved near and far aiming skills. Participants (N = 8) were required to step forward and kick a ball to hit a target. The top three scorers were defined as the High-score group, and the three low scorers were defined as the Low-score group. Analysis indicated that the High-score group was characterized by longer quiet eye durations, which were defined as the final fixation durations on the target prior to the initiation of a kicking movement, than the Low-score group in the preparation phase. The High-score group also set their visual pivot on the frontal space between the target and the ball in the kicking phase. These two visual behaviors of the High-score group are important for soccer players to kick a ball successfully with the inside of the foot.

An ergonomic evaluation of lens accommodation related to visual circumstances

This study is intended to make clear the relationships between a number of external conditions (target luminance, size, etc.), dynamic responsiveness of the lens accommodation, and microfluctuation. Further, the effects of ageing and the difference between monocular and binocular observations are examined. These studies established that age factors have a large bearing on the ability of the lens to focus on an object, as well as affecting such abilities as the responsiveness of the lens accommodation, amplitude of lens accommodation response, microfluctuation, and contraction and relaxation time. Of these accommodation functions, such factors as contraction and relaxation time clearly reflect the ease of seeing an object. Clear relationships between the amount of diopter and the ease of seeing an object were also observed. Further, it was established that a binocular observation is more responsive (velocity of contraction) than a monocular one. As to the microfluctuation, on the other hand, clear effects of age on its spectrum distribution were recognized but no definite correlations concerning the ease of seeing an object were observed.

Visual capability to receive character information. Part I: How many characters can we recognize at a glance?

A study was made on the capability to receive character information and the factors restricting it. The study showed that the capability indicated by the memory span was limited by the average number of characters for words that are made up of individual characters, and calculated in terms of information quantity, there was no difference among the individual characters. The differences in memory span, depending on the size of the pattern presented, was negligible. The difference in the way characters were arranged produced the difference in memory span saturation. This phenomenon is explained by the nature of the lateral interference effect working among the adjacent characters.

Relation between flicker fusion threshold and retinal positions.

The critical flicker frequencies (CFF) were determined for various locations on the retina. Under the conditions in which pupil size varies little with target luminance and size for a retinal location, two findings were obtained. First, the relation between the CFF value and the retinal location depends basically upon the density distribution of the receptor cells (cones and rods) on the retina. Second, when a large test field is employed, the peripheral area shows a maximal CFF value. These characteristics are explicable in terms of the retinal structure and by assuming some functions for it.

Subjective Frequency in Flicker Perception

The discrepancy between the actual flicker frequency and the perceived rate was investigated. We tried to quantify the subjective rate of successive visual flicker by matching it with a second stimulus, the audio flutter. The wave form of each stimulus employed in the present study was sinusoidal. The auditory stimulus employed as a reference was a pure tone which was frequency-modulated by a sine wave. The perceived rate of flicker increases approximately in direct proportion to the frequency presented when target size is small and tends to be lower than the actual rate when target size is large. Perceived rate never exceeds approximately 10 Hz regardless of the presented flicker frequency or the luminance of the target. These tendencies are observed commonly in the fovea and in the periphery of the retina.

New electronic media and the human interface

Discussion is focused on the relationship between the new media and the human visual system. First, the process of information transmission in the human visual system is shown as a hierarchically structured model. Second, examples of the human interface in the development of a Japanese teletext system are shown, such as desired luminance and contrast, or favourable colour combination, or how to make superimposed sentences on screen easy to read. Third, examples of the human interface in the development of Hi-Vision, or High Definition Television (HDTV), are discussed, namely the conditions required for Hi-Vision from the standpoint of visual characteristics, the visual effects of Hi-Vision, and an objective evaluation of psychological effects of Hi-Vision.