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Philip A. Duke, Ian P. Howard; Are vertical disparites pooled over depth?. Journal of Vision 2004;4(8):596. doi: 10.1167/4.8.596.
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© ARVO (1962-2015); The Authors (2016-present)
To produce representations of stereoscopic 3-D surfaces, the visual system uses vertical disparities to disambiguate depth information provided by horizontal disparities. Duke & Howard (2003) showed that gradients of vertical disparity are pooled over a very narrow range of horizontal disparities (±5 arcmin) for judgements of surface curvature about a vertical axis. In the present study we examined whether vertical size and vertical shear disparities are also processed in a horizontal disparity-specific way. Both size and shear vertical disparities are independent of depth, so pooling would provide more accurate estimates of surface slant and inclination respectively. In Experiment 1 we tested the hypothesis that vertical size disparities are pooled over depth. Test stimuli were 2 superimposed frontal arrays of elements separated in depth by a range of horizontal disparity offsets. Each array was given a different vertical size disparity (+ and − 8% magnification). The arrays should appear oppositely slanted if their vertical size disparities are not pooled. Observers performed a sequential slant matching task for each array. We found horizontal disparity specific processing of vertical size disparity similar to that for curvature judgements. In Experiment 2 we examined whether vertical shear disparities are pooled over depth for judgements of inclination about a horizontal axis. Test stimuli were similar to those in Experiment 1 but each array had a different magnitude of vertical shear disparity (+ and − 5°). We found that vertical shear disparity is pooled over a large range of horizontal disparities, which seems to be determined by the limits of stereopsis.
Natural Sciences and Engineering Research Council of Canada
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