The objective of this study is to describe the adaptability of the central nervous system to safely cross a narrow aperture when the space required for passage is transiently extended with external objects under different locomotor constraints. In one of four locomotion forms (normal walking, walking while holding a 63-cm horizontal bar with or without rotating the shoulders to cross a door opening, and wheelchair use), nine participants were asked to pass through an aperture created by two doors (the relative aperture widths were 1.02, 1.10, and 1.20 times their maximum horizontal dimension under each form of locomotion) without a collision. The kinematic analyses showed that, when the participants rotated their shoulders while walking and holding a bar, virtually the same locomotor patterns as those during normal walking were observed: shoulder rotation was regulated well in response to the width of an aperture, and no collisions occurred. When shoulder rotations were restricted while walking and holding a bar or using a wheelchair, a large reduction in the speed of movement was observed as the participants approached the door, and, furthermore, the modulation in speed was dependent on the width of the aperture. In addition, the participants crossed at the center of aperture more accurately; nevertheless, collision sometimes occurred (more frequently, during wheelchair use). These findings reveal that movement constraints on shoulder rotation are likely to be a critical factor in determining whether quick and successful adaptation takes place.

Locomotion using a wheelchair requires a wider space than does walking. Two experiments were conducted to test the ability of nonhandicapped adults to estimate the spatial requirements for wheelchair use. Participants judged from a distance whether doorlike apertures of various widths were passable or not passable. Experiment 1 showed that participants underestimated the spatial requirements for wheelchair use but overestimated the spatial requirements for walking. Experiment 2 showed that their underestimation improved but was not completely eliminated after 8 days of practice passing through apertures. Analyses of wheelchair performance in the practice condition showed that the underestimation may have arisen from misperception of the positions of the hands when the participants were grasping the wheelchair hand-rims. The theoretical and practical implications of these findings are discussed.

Palmprint images taken from a camera are distorted due to movement of a hand and fingers. To achieve reliable palmprint recognition, it is necessary to employ a recognition algorithm dealing with nonlinear distortion, while the conventional algorithms only consider the rigid body transformation between palmprint images. This paper proposes a palmprint recognition algorithm using phasebased correspondence matching. In order to handle nonlinear distortion, the proposed algorithm (i) finds corresponding points between two images using phase-based correspondence matching and (ii) evaluates a similarity between local image blocks around the corresponding points. Experimental evaluation using a palmprint image database demonstrates efficient recognition performance of the proposed algorithm compared with conventional algorithms.

BackgroundOlder adults could not safely step over an obstacle unless they correctly estimated their physical ability to be capable of a successful step over action. Thus, incorrect estimation (overestimation) of ability to step over an obstacle could result in severe accident such as falls in older adults. We investigated whether older adults tended to overestimate step-over ability compared with young adults and whether such overestimation in stepping over obstacles was associated with falls.MethodsThree groups of adults, young-old (age, 60–74 years; n, 343), old-old (age, >74 years; n, 151), and young (age, 18–35 years; n, 71), performed our original step-over test (SOT). In the SOT, participants observed a horizontal bar at a 7-m distance and estimated the maximum height (EH) that they could step over. After estimation, they performed real SOT trials to measure the actual maximum height (AH). We also identified participants who had experienced falls in the 1 year period before the study.ResultsThirty-nine young-old adults (11.4%) and 49 old-old adults (32.5%) failed to step over the bar at EH (overestimation), whereas all young adults succeeded (underestimation). There was a significant negative correlation between actual performance (AH) and self-estimation error (difference between EH and AH) in the older adults, indicating that older adults with lower AH (SOT ability) tended to overestimate actual ability (EH > AH) and vice versa. Furthermore, the percentage of participants who overestimated SOT ability in the fallers (28%) was almost double larger than that in the non-fallers (16%), with the fallers showing significantly lower SOT ability than the non-fallers.ConclusionsOlder adults appear unaware of age-related physical decline and tended to overestimate step-over ability. Both age-related decline in step-over ability, and more importantly, overestimation or decreased underestimation of this ability may raise potential risk of falls.