Hirokazu Iwase

Usability of touch-panel interfaces for older adults.

The usability of a touch-panel interface was compared among young, middle-aged, and older adults. In addition, a performance model of a touch panel was developed so that pointing time could be predicted with higher accuracy. Moreover, the target location to which a participant could point most quickly was determined. The pointing time with a PC mouse was longer for the older adults than for the other age groups, whereas there were no significant differences in pointing time among the three age groups when a touch-panel interface was used. Pointing to the center of a square target led to the fastest pointing time among nine target locations. Based on these results, we offer some guidelines for the design of touch-panel interfaces and show implications for users of different age groups. Actual or potential applications of this research include designing touch-panel interfaces to make them accessible for older adults and predicting movement times when users operate such devices.

Evaluation of mental workload by fluctuation analysis of pupil area

It is generally known that the pupil is regulated by the autonomic nervous system. In this study, an attempt was made to assess mental workload on the basis of fluctuation rhythm of pupil area. Controlling the respiration interval, the pupil area during mental tasking was measured for 1 min. The respiration curve was measured simultaneously to monitor the respiration interval. Two mental tasks were used. One was a division task, the work level of which was set to two, three, four and five number of digits of the dividend. The other was a Sternberg memory search task, which had four work levels defined by the number of memory set. In the Sternberg memory search, the number of memory sets changed from five to eight. In such a way, the mental workload induced by mental loading was changed. As a result of calculating an AR power spectrum, we could observe two peaks which corresponded to the blood pressure variation and respiratory sinus arrhythmia under a low workload condition. With increasing workload, the spectral peak related to the respiratory sinus arrhythmia disappeared. The ratio of the power at the low frequency band (from 0.05-0.15 Hz) to the power at the respiration frequency band (from 0.35-0.4 Hz) increased with work level. In conclusion, the fluctuation of the pupil area can be used as a promising means to evaluate mental workload or autonomic function to supplement well-used heart rate variability measures.

Empirical study on improvement of usability -for touch-panel for elderly - comparison of usability between touch-panel and mouse

In this study. we clarified the differences in the pointing time required when using a touch panel and a PC mouse for three age group: young, middleaged. and elderly. Furthermore, we constructed a performance model for a touch-panel operation (Experiment 1). The model is based on an equation that estimates the time required for the pointing task. Moreover. we investigated the visual interference caused by a multi-target presentation (Experiment 2 ) . I n Experiment 1. the experimental factors were target area, target distance, and approach angle to a target. In Experiment 2, the experimental factors were target area, approach angle to a target, and target position. A fully within-subject design was used. The pointing time and the error rate were measured for both a touch panel and a PC mouse. In Experiment 1, the pointing time with the PC mouse for the elderly group was significantly longer than that for the other age groups (young and middle-aged). O n the other hand, there was no significant difference in the pointing time by age group for the use of the touch panel. With respect to differences in the error rate by age group. there were none with either t h e touch panel or the PC mouse. These results indicate that a direct-input device, such 86 a touch panel, would be superior to an indirect-input device. such b4 a PC mouse, for older adults whenever i t is desired to prevent the influence of age. In Experiment 2. the difference in the pointing time between multi-target and singletarget conditions was calculated by using the proposed model. The delay caused by visual interference for the right-hand target was longer than that for the left-hand target, and that for the upper target was longer than that for the lower target. Keyword-elderly person, aging. touch panel. performance model. Fitts’ law

Chaotic analysis of body sway

In this study, the chaotic features of postural steadiness were investigated using a reconstructed phase portrait, fractal dimension and first Lyapunov exponent, as well as the basic measures of postural steadiness. The experimental variables were presence of visual information (eyes-open and eyes-closed) and postures (standing straight on both feet: SBF, standing straight on left foot only: SLF, standing straight on right foot only: SRF). The first Lyapunov exponent tended to be larger for SRF and SLF conditions as compared with SBF condition, which showed that the postural control system under SLF and SRF conditions was more chaotic. As for SLF and SRF conditions, the first Lyapunov exponent tended to be smaller for the eyes-closed condition than for the eyes-open condition. On the other hand, the first Lyapunov exponent for the SBF condition was smaller irrespective of the presence of visual information. The fractal dimensions of SLF and SRF conditions were less than 2.0 for both the eyes-open and eyes-closed conditions. Moreover, the fractal dimension of the eyes-closed condition tended to be lower than that of the eyes-open condition. We can conclude that the postural control system under SLF and SRF conditions behaves more chaotically than the SBF condition, and leads to the instability of COP.

Effectiveness of cognitively engineered human interface design

In general, it is hypothesized that a cognitively engineered interface design is superior to an interface design that is not cognitively engineered. However, this hypothesis has not been empirically verified. Two decision-making tasks were used to verify the effectiveness of cognitively engineered interface design. Six cognitive engineering design principles were extracted from the literature on human computer interaction, and explicitly applied to the interface design in each decision-making task. Reaction time and accuracy were experimentally investigated. The cognitively engineered interface was compared with an interface that was not cognitively engineered. As a result, the cognitively engineered interface was found to be superior to an interface which was not cognitively engineered across reaction time in both of decision-making tasks.

Analysis of chaotic dynamics in EEG and its application to assessment of mental workload

An attempt was made to evaluate mental workload using chaotic analysis of EEG, EEG signals registered from Fz and Cz during a mental task (mental addition task) were recorded and analyzed using chaotic measures such as attractor plot, fractal dimension and Lyapunov exponent, which are used to clarify chaotic dynamics, to investigate whether mental workload could be assessed using these measures. The largest Lyapunov exponent for all experimental conditions took positive values, which indicated chaotic dynamics In the EEG signals. However, the authors could not evaluate mental workload using the largest Lyapunov exponent or attractor plot. The fractal dimension, on the other hand, tended to increase with the work level. The authors concluded that the fractal dimension can be used to evaluate the mental state, especially a mental workload induced by mental task loading.

Discussion on skillful baseball pitch using three-dimensional cinematographic analysis. Comparison of baseball pitch between skilled and unskilled pitchers

The purpose of this study was to compare baseball pitches between skilled and unskilled pitchers using a three-dimensional cinematographic analysis. Nine baseball pitchers were used as subjects. These subjects were rated by the coach as skilled and unskilled pitchers. The pitching motions were filmed by two high-speed cameras. The time series of three-dimensional landmark coordinates of the subject and the ball during the baseball pitch were calculated using the DLT method. First, the index called SFD which expresses quantitatively the dispersion of the shoulder joint on the opposite side of the throwing arm was proposed to compare the SFD between skilled and unskilled pitchers. Next, the kinematic parameters such as abduction/adduction angle at the shoulder joint of the throwing arm were calculated to investigate whether the pitching motion for the skilled pitchers were less different between types of pitches (fastball and curveball pitches) as compared with that for the unskilled pitchers. The results indicated that the SFD of skilled pitchers was smaller than that of the unskilled pitchers. It was also found that the kinematic variables for the skilled pitchers did not vary between types of pitches.

Chaotic analysis of focal accommodation system and pupil area during VDT work

Evaluation of stress during a VDT task is important when designing proper human-computer interactions. The purpose of this research is to show that stress during VDT tasks can be evaluated using chaotic features such as the fractal dimension and the first Lyapunov exponent for the focal accommodation system and the pupil area. As for step control measurement and fixed target measurement, the fractal dimension tends to decrease over time. This shows that the fractal dimension for the focal accommodation system and the pupil area can be used to evaluate stress during VDT tasks. The first Lyapunov exponent took positive values. Not only the fractal dimension but also the first Lyapunov exponent in the fixed target measurement was larger than those in the linear control and step control measurements. The chaotic property in the fixed target measurement was higher than that in the linear control and step control measurements. However, the first Lyapunov exponent hardly changed over time for all three accommodation measurements.

Visual attention models-object-based theory of visual attention

According to the object-based theory, visual attention can be divided within a single object more efficiently than between separate objects. In this paper, the object-based theory of visual attention was validated through a comparison with the spatially based view, suggesting that visual attention is directed to unparsed regions of space. In testing this theory, various perceptual judgements of location were given by subjects in response to objects. Among the variables in presentation were: the direction of the objects, the distance between two locations, the number of objects involved and the display condition (joined, congruent, incongruent, etc.). In other words, the single- and two-object displays were compared by investigating the effects of these experimental factors. As a result, the object-based theory of visual attention was found to be applicable to hexagons of equal convexity, but not applicable to the other forms within the range of this experiment.

Rate of information processing during simultaneous presentation of auditory and visual information

If the display time of TV pictures, etc. is not sufficient, it is impossible to understand the displayed information. This paper investigated the relationship between the given amount of simultaneously presented visual and auditory information and the display time required to process that information in order to determine optimal display time in TV pictures, etc. The relationship was defined as a function of the co-relevance of the visual and auditory information presented. As a result, the co-relevance of the two types of information did not affect the relationship. The increment of display time required to process both types of information during simultaneous presentation was nearly constant for each amount of information. Therefore, the rate of information processing did not differ between single- and simultaneous-presentation conditions.