Abstract
People with normal visual systems use both stereo and monocular cues for 3D perception. However, about 10% of the population are stereoblind and have to rely on other cues. Does stereoblindness change how monocular cues are processed? We investigated this question for the case of stereo and texture cues to 3D slant. For normal people, slant estimates from monocular texture are a highly nonlinear function of slant, with large bias toward frontal at low slants, while slant estimates from binocular texture are close to linear. Slant discrimination from monocular texture is also highly dependent on slant, with poor sensitivity at low slants, while discrimination from binocular texture is more uniform. If biases and poor sensitivity of slant from texture is due to fundamental limitations ability to extract information from texture, then stereoblind people would show the same effects. Alternatively, long-term experience with stereoblindness might cause some adaptive changes, such as increased sensitivity to texture cues or rescaling of the relation between texture cues and perceived slant. We tested this by comparing slant estimation and discrimination performance of stereoblind and normal observers (N=48) for textured surfaces presented both monocularly and binocularly. In the monocular conditions, we found no difference between groups for either task; both groups showed the same biases in slant estimation and equivalent discrimination thresholds. Experience with stereoblindness does not appear to have changed interpretation of slant from texture nor improved sensitivity. As expected, binocular viewing improved slant discrimination for normal observers but not for stereoblind observers. However, the stereoblind observers showed a small but significant reduction in frontal biases in the binocular conditions, which is likely due to some phenomenal difference between monocular and binocular viewing. In conclusion, we found no evidence that stereoblindness produces of adaptive changes in use of texture information for 3D perception.
Acknowledgement: China Postdoctoral Science Foundation (NO. 2018M630410)