Perceiving slipperiness and grip: A meaningful relationship of the shoe-ground interface.

The present study investigated the relationship between objective measurements of the available (CoF), the utilized (CoF) coefficient of friction and subjective perception of grip or slipperiness. It was hypothesized that significant correlations exist between the perception of grip or slip and the CoF during sports movement and that a minimum CoF was needed to ensure an optimal grip/slipperiness perception. Eighteen healthy active females performed forward and backward cutting tasks onto a forceplate.

Perception of Affordance during Short-Term Exposure to Weightlessness in Parabolic Flight.

We investigated the role of the visual eye-height (VEH) in the perception of affordance during short-term exposure to weightlessness. Sixteen participants were tested during parabolic flight (0g) and on the ground (1g). Participants looked at a laptop showing a room in which a doorway-like aperture was presented.

Perception of affordances during long-term exposure to weightlessness in the International Space station.

On Earth, visual eye height (VEH)--the distance from the observer's line of gaze to the ground in the visual scene--constitutes an effective cue in perceiving affordance such as the passability through apertures, based on the assumption that one's feet are on the ground. In the present study, we questioned whether an observer continues to use VEH to estimate the width of apertures during long-term exposure to weightlessness, where contact with the floor is not required. Ten astronauts were tested in preflight, inflight in the International Space Station, and postflight sessions.

Influence of gaze elevation on estimating the possibility of passing under high obstacles during body tilt.

We investigated the influence of gaze elevation on judging the possibility of passing under high obstacles during pitch body tilts, while stationary, in absence of allocentric cues. Specifically, we aimed at studying the influence of egocentric references upon geocentric judgements. Seated subjects, orientated at various body orientations, were asked to perceptually estimate the possibility of passing under a projected horizontal line while keeping their gaze on a fixation target and imagining a horizontal body displacement.