Visual Estimation of Spatial Requirements for Locomotion in Novice Wheelchair Users.

Abstract

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.

Visual estimation of apertures for wheelchair locomotion in novices: Perceptual judgment and motor practice.

“…Skilled wheelchair users showed an RPB of 1.02 from Flascher et al (1995) and 1.03 from Savelsbergh et al (1998). This confirms that walkers and skilled wheelchair users similarly judge and reduce risks, although skilled wheelchair users adopt a smaller safety margin (Higuchi et al, 2004).…”

“…The protocol was divided into five parts as suggested by Higuchi et al (2004). The practice group was subjected to (i) visual estimation of different apertures in the "walking" situation, (ii) familiarization with the wheelchair for 5 min, (iii) pre-practice visual estimation of different apertures in the "wheelchair" situation, (iv) motor practice with the wheelchair, passing through different apertures, and (v) postpractice visual estimation of different apertures in the "wheelchair" situation.…”

“…In addition to the role of experience on the accuracy of judgments, a relevant methodological issue is the definition of the RPB to allow comparisons across studies. Higuchi et al (2004) noted that distinct notions of "maximum aperture width as impassable" and "minimum aperture width as passable" could result in a difference of approximately 5 cm among studies. These authors suggested applying a typical psychophysical method based on the proportion of passable judgments as a function of aperture widths and defining the perceptual boundary as the value of the aperture width at which the function passes through the 50% level.…”

“…Higuchi et al (2004) used a task of judging the minimum width of a passable aperture in novices. One group of participants was given 10-14 trials of motor practice (experiment 1) using the wheelchair to pass through apertures of varying widths.…”

Nesting in perception of affordances for stepping and leaping

“…While this is possible in at least some cases, it does not explain cases in which participants overestimate their action capabilties. For example, research has shown that novice wheelchair users generally overestimated their ability to roll through an aperture (Higuchi, Takada, Matsuura, & Imanaka, 2004), and toddlers overestimated their ability to walk down slopes (Adolph, 2008). It is also does not explain cases in which perceivers underestimate their ability to perform a behavior that poses little or no accident or injury risk (e.g., overhead reaching while standing on the floor; Wagman & Morgan, 2010).…”