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K. A. Turano, F. C. Fortenbaugh, J. C. Hicks, L. Hao; Peripheral Visual Field Loss Compresses Space in Visual Memory. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2345.
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© ARVO (1962-2015); The Authors (2016-present)
To determine how the peripheral visual field (VF) affects the representation of object locations in 3D space.
Normally sighted persons (n = 21) with simulated VF loss (gaze-contingent restriction: 10, 20, or 40 deg diam.) were tested on the locations of six objects in a virtual environment. Nine persons with retinitis pigmentosa (RP) were also tested (VFs of 5 to 30 deg). Participants first explored the object locations by walking to each of the six objects. The objects were then removed, and the task was to walk to where the objects had been located. Distance errors and the area enclosing the estimated object locations were calculated. Areas for near (<5m of the starting position) and far space were computed separately. Predictions for the RP data were derived from the 95% confidence intervals of the simulated VF-restriction data. A second experiment, in which participants made distance and height estimates, was run to test whether the VF effects occurred at a perceptual level.
Simulated VF loss. VF size had a significant effect on the distance errors; distance was increasingly compressed as VF decreased (p<0.01). The distribution of distance errors was significantly different from 0 in the 10 deg condition (p<0.01) revealing a compression of space, but not in the 20 or 40 deg conditions. VF size had a differential effect on spatial memory depending on whether the objects were in near or far space, with only far-space area affected (p<0.01) (see fig below). The results of the second experiment showed underestimations of distance but not height and no effect of VF size. RP data. Two-thirds of the RP participants had distance errors and far-space areas that fell within the predicted range. The RP data that fell outside the predicted range typically showed less compression. Two-thirds of the near-space areas were closer to the true areas than predicted from the simulated data.
Loss of the peripheral VF leads to a systematic compression of far space in visual memory. Some persons with real peripheral field loss compensate to a certain extent, perhaps from an increased use of self-motion cues.
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