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Flip Phillips, Martin Voshell; Distortions of posterior visual space. Journal of Vision 2002;2(7):717. doi: 10.1167/2.7.717.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. The study of spatial vision is a long and well traveled road (which, of course, converges to a point at the horizon). Its various distortions have been widely investigated empirically, and most concentrate, pragmatically, on the space anterior to the observer. The visual world behind the observer has received less attention; it is the structure of this space that these experiments address.
Methods. An initial ‘field’ experiment using surveyed locations and physical poles arranged in a large pasture was followed by several experiments using a computer graphics simulation of the ecological setup. A series of egocentric pointing tasks were performed in which the subject was instructed to make a controlled observation of their posterior visual space, after which they adjusted a mechanical pointer to indicate the perceived location of an object in that environment.
Results. Subjects' responses reflect systematic and consistent distortions in their perception of the visual world behind them. For the various presentation and observation conditions the subjects consistently ‘spread’ their perceptual representation of their posterior space in a hyperbolic fashion. Directions to distant, peripheral locations were consistently overestimated by 5 to 10 degrees, and variability increased as the target was moved toward the center of the observer's back.
Conclusions. The perceptual representation of posterior visual space is of primary importance in certain sports, such as rowing, and in vehicular navigation (c.f. Voshell and Phillips in these proceedings). Our results show systematic perceptual distortions in the posterior visual world when viewed statically. Investigations currently underway examine these distortions when moving through and navigating this space.
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