Academic journal article Attention, Perception and Psychophysics

Confinement Has No Effect on Visual Space Perception: The Results of the Mars-500 Experiment

Academic journal article Attention, Perception and Psychophysics

Confinement Has No Effect on Visual Space Perception: The Results of the Mars-500 Experiment

Article excerpt

Published online: 28 November 2013

© Psychonomic Society, Inc. 2013

Abstract People confined to a closed space live in a visual environment that differs from a natural open-space environment in several respects. The view is restricted to no more than a few meters, and nearby objects cannot be perceived relative to the position of a horizon. Thus, one might expect to find changes in visual space perception as a consequence of the prolonged experience of confinement. The subjects in our experimental study were participants of the Mars-500 project and spent nearly a year and a half isolated from the outside world during a simulated mission to Mars. The participants were presented with a battery of computer-based psychophysical tests examining their performance on various 3-D perception tasks, and we monitored changes in their perceptual performance throughout their confinement. Contrary to our expectations, no serious effect of the confinement on the crewmembers' 3-D perception was observed in any experiment. Several interpretations of these findings are discussed, including the possibilities that (1) the crewmembers' 3-D perception really did not change significantly, (2) changes in 3-D perception were manifested in the precision rather than the accuracy of perceptual judgments, and/or (3) the experimental conditions and the group sample were problematic.

Keywords Confinement · Visual space perception · Perspective · Mars-500 · Size judgments · Size constancy · Change blindness

Astronauts during spaceflight are exposed to a visual environ- ment that differs in many important aspects from the familiar environment on Earth. For instance, during exposure to weightlessness, the gravitational frame of reference is absent. The directions up and down are no longer unequivocally defined, and the perception of upright becomes relatively more body-defined (Clément, Arnesen, Olsen, & Sylvestre, 2007; Glasauer & Mittelstaedt, 1998). In such perceptual ambiguity, the task of spatial navigation, or even a simple search for objects on board, becomes challenging (Clément & Reschke, 2008;Oman,2007). Moreover, in the confined environment of a spacecraft or space station, all visible objects stay within a few meters from the observer'sviewpoint,and the visibility of farther objects is precluded. This visual field restriction does not allow a crewmember to perceive objects relative to the position of the horizon, thus making size and distance estimation rather difficult (Rand, Tarampi, Creem- Regehr, & Thompson, 2012). In addition to microgravity and confinement, astronauts are also exposed to a variety of other stressors during spaceflight, such as altered light:dark cycles, sleep deprivation, and high mental and physical workloads (Clément & Reschke, 2008), which altogether may adversely affect their 3-D perception.

A few psychophysical experiments have attempted to de- termine how crewmembers' three-dimensional (3-D) percep- tion is changed by the short-term microgravity generated during parabolic flights. In an experiment by Clément, Lathan, and Lockerd (2008), subjects were asked to adjust the length of a particular dimension (height, width, or depth) of a 3-D cube presented in a virtual-reality environment until all three dimensions had the same apparent length. The data demonstrated that subjects judged the cube to have a smaller height, slightly larger width, and longer depth. The authors attributed those errors in perceived dimensions to a general tendency to perceive the straight-ahead direction as being lower in microgravity than in normal gravity, which is in accordance with frequent astronaut reports indicating that spacecraft interiors look longer and higher than they really are (Lathan, Wang, & Clément, 2000). Furthermore, Villard, Garcia-Moreno, Peter, and Clément (2005)demonstrateda decrease in the strength of geometric illusions based on per- spective, such as the Ponzo, Müller-Lyer, and horizontal- vertical illusions, in a microgravity environment. …

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