50 Years of Stereoblindness: Reconciliation of a Continuum of Disparity Detectors With Blindness for Disparity in Near or Far Depth

Abstract

Whitman Richards (1932–2016) discovered some 50 years ago that about 30% of observers from the normal population exhibit stereoblindness: the disability to process binocular disparities in either far or near depth. We review the literature on stereoblindness entailing two insights. First, contemporary scholars in stereopsis undervalue the comprehension that disparity processing studies require precise assessments of observers’ stereoblindness. We argue that this frequently leads to suboptimal interpretations. Second, there is still an open conundrum: How can the established finding that disparity is processed by a continuum of detectors be reconciled with the disability of many observers to process a whole class of far or near disparities? We propose, based upon integration of literature, that an asymmetry between far and near disparity detection at birth—being present for a variety of reasons—can suppress the typical formation of binocular correlation during the critical period for the development of stereopsis early in life, thereby disabling a whole class of far or near disparities.

Crowding in depth for binocular and monocular observation

“…Moreover, our sample was only screened for stereoability by using the TNO, which is based on red-green anaglyphs. Thus, the effect sizes in the current data might be diminished by inter-individual differences in stereoability (Dorman & van Ee, 2017;Kooi et al, 2010;van Ee & Richards, 2002) and could have benefited from a stricter criterion (Westheimer, 2013). For example, van Ee and Richards (2002) propose a more elaborate test of stereovision.…”

“…A blank screen afterward ensured that stimuli remained in the iconic memory for processing (Sperling, 1960). In addition, within a presentation duration of 20 ms accommodative (e.g., Kasthurirangan & Glasser, 2006) or vergence movements (e.g., Bucci, Kapoula, Yang, & Bremond-Gignac, 2006) were impossible (see also Dorman & van Ee, 2017). Participants were instructed to release the starting key and indicate the opening direction of the target Landolt ring as fast and as correctly as possible.…”

The prevalence and diagnosis of ‘stereoblindness’ in adults less than 60 years of age: a best evidence synthesis

“…According to the first view, each is processed in separate systems (see Mustillo). According to the opposite view, there is a continuum of disparity sensitivities . Whether one view or the other is correct, the important fact is the following: some observers can show normal stereoacuity for one type of disparity and be stereoblind to the other .…”

Factors limiting sensitivity to binocular disparity in human vision: Evidence from a noise-masking approach

“…Human stereoacuity thresholds smaller than 5 seconds of arc (arcsec) have been obtained (McKee, 1983;Stevenson, Cormack, & Schor, 1989). Previous studies, however, have shown considerable individual differences in stereoacuity across the population (Bosten et al, 2015;Dorman & van Ee, 2017;Hess et al, 2015;Hess et al, 2016;Zaroff, Knutelska, & Frumkes, 2003). In this study, we investigate the variability for a relative disparity detection task.…”

“…Alternatively, these results can also be explained by a model in which stereo processing occurs in a series of stages. If the direction of the disparity is determined at a relatively late stage, then it may be this step that is failing (Dorman & van Ee, 2017;Landers & Cormack, 1997).…”