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In order to intercept a moving target such as a baseball with high spatio-temporal accuracy, the perception of the target's movement speed is important for estimating when and where the target will arrive. However, it is unclear what sources of information are used by a batter to estimate ball speed and how those sources of information are integrated to facilitate successful interception. In this study, we examined the degree to which kinematic and ball-flight information are integrated when estimating ball speed in baseball batting. Thirteen university level baseball batters performed a ball-speed evaluation task in a virtual environment where they were required to determine which of two comparison baseball pitches (i.e., a reference and comparison stimuli) they perceived to be faster. The reference and comparison stimuli had the same physical ball speed, but with different pitching movement speeds in the comparison stimuli. The task was performed under slow (125 km/h) and fast (145 km/h) ball-speed conditions. Results revealed that the perceived ball-speed was influenced by the movement speed of the pitcher's motion, with the influence of the pitcher's motion more pronounced in the fast ball-speed condition when ball-flight information was presumably less reliable. Moreover, exploratory analyses suggested that the more skilled batters were increasingly likely to integrate the two sources of information according to their relative reliability when making judgements of ball speed. The results provide important insights into how skilled performers may make judgements of speed and time to contact, and further enhance our understanding of how the ability to make those judgements might improve when developing expertise in hitting. more...

There remains a question about whether and to what extent perception–action coupled response in virtual reality are equal/unequal to those in the real world or physical reality. The purpose of this study was to identify the differences in the environmental effect of virtual presentation on the motor responses of a one-handed ball catching. Thirteen healthy participants were instructed to catch an approaching ball projected at three speeds in a real laboratory room and in a room-sized virtual reality system (CAVE) that simulated those real situations with two- or three-dimensional display settings. The results showed that the arm movement time, which denotes the duration of arm-raising motion (shoulder flexion), was significantly longer in the virtual reality than that in the physical reality at the fast ball speed condition. The shoulder flexion velocities, calculated as the average angular velocity of shoulder flexion over the arm movement time, were significantly lower in the virtual reality than in the physical reality at the medium and fast ball speed conditions. The electromyography onsets, derived from anterior deltoid, biceps brachii, and flexor carpi radialis muscles of the catching arm, appeared before and significantly closer to the initiation of arm raising in the two-dimensional virtual reality than both in the physical reality and in the three-dimensional virtual reality. The findings suggest that simulation of virtual reality may induce a modulation in the motor responses of the catching arm, which is different from natural motion that appeared in the real world. On the contrary, the effect of ball speed generally found in real setting was maintained in the current CAVE experiment. more...

Virtual reality (VR) could be used to set up a training protocol to improve one's collision-avoidance behavior. In our previous study, we developed a VR system for training older individuals to walk through an aperture in a manner that is both safe (i.e., no collision) and efficient (i.e., no exaggerated behavior to ensure collision avoidance). In the present study, we made several modifications to the VR system in terms of enriched feedback (vibratory stimulation for virtual collisions and the addition of positive feedback for successful trials) and gradual increase in task difficulty during training to strengthen the skill transfer. Nineteen older adults (74.4 ± 5.3 years of age) and 21 younger adults (25.1 ± 5.0 years of age) participated. They were randomly assigned to one of two training groups: the intervention group (older: n = 10; younger: n = 10) or the control group (older: n = 11; younger: n = 9). The experiment consisted of pre- and post-training tests in a real environment and training in a VR environment. During training, participants held a horizontal bar while stepping in place as if a VR image on the screen were moving in response to their stepping. Participants in the intervention group tried to pass a narrow aperture without collision while attempting to minimize their body rotation to avoid collision as much as possible. The criterion upon which the collision-avoidance behavior was regarded as successful became incrementally more demanding as participants successfully met the previous criterion. Participants in the control group passed through a very wide aperture, so that collision-avoidance behavior was unnecessary. A comparison between pre- and post-training test performances showed that, for both older and younger adults in the intervention group, the spatial margins became significantly smaller, while the success rate remained unchanged. For those in the control group, neither the spatial margin nor the success rate was improved. These results suggest that the three modifications made for the VR system contributed to improvement of the system and helped participants transfer the behavior learned from the VR environment to real walking. more...