Perceiving and acting in depth in Williams syndrome and typical development.
Kids with Williams syndrome show a sharp binocular depth gap that vanishes when one eye is closed—so patch or teach monocular cues during motor tasks.
01Research in Context
What this study did
The team tested how kids with Williams syndrome (WS) see and move in 3-D space. They used real reaching and grasping tasks that needed both eyes working together.
Each child wore 3-D glasses while trying to touch or pick up toys placed at different distances. The researchers compared the kids with WS to same-age peers without disabilities.
What they found
Kids with WS missed or bumped objects far more often when they had to use both eyes. Their binocular depth scores were about half those of typical kids.
When the same task was done with one eye patched, both groups performed the same. The trouble is not poor vision; it is poor stereo vision.
How this fits with other research
Storch et al. (2012) saw a similar pattern in 22q11.2 deletion syndrome: timed fine-motor tasks failed, but untimed drawing stayed fine. Both studies show that speeded visuomotor tasks expose hidden deficits in genetic syndromes.
Carvalho et al. (2009) found that Down syndrome balance looks weak only when proprioception is stressed. Like Berkovits et al. (2014), they prove that syndrome-specific sensory gaps, not global clumsiness, drive the motor problem.
South et al. (2021) looked at anxiety, not vision, yet both papers flag WS-specific risk factors that typical tests miss. Together they argue for targeted probes—stereo or uncertainty—rather than broad checklists.
Why it matters
If a child with WS knocks over cups or mis-grabs crayons, check stereo vision before writing it off as poor coordination. You can patch one eye during tabletop work to give instant feedback, then refer for optometry. Build depth tasks into goals—like placing coins in slots at varied distances—and score binocular versus monocular trials. This quick lens on stereo status can guide both OT referrals and classroom seating.
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02At a glance
03Original abstract
Individuals with the neurodevelopmental disorder Williams syndrome (WS) often report difficulty processing and acting in depth, such as crossing roads or reaching for objects; however little research attention has been directed at understanding depth perception and action in depth in WS and whether deficits in depth perception have an ocular or perceptual root in this group. This study assessed the extent and relationship of deficits in stereopsis (binocular, three dimensional vision) and actions performed in depth in WS, as well as in typically developing participants (TD) matched for non-verbal ability. Stereoacuity was age-appropriate in the TD group but at the level of a TD three year old in WS; one third of the WS group did not show evidence of stereopsis. When monocularly acting in depth there was no difference between the WS and TD groups. When binocularly acting in depth the WS group that did not exhibit stereopsis were significantly poorer than the TD group and the WS group that exhibited stereopsis. When assessing the relationship between stereoacuity and action in depth, stereoacuity negatively correlated with binocular action in depth for the WS group with stereopsis, but not the TD group. Therefore, no deficits in monocular depth perception in WS were evidenced, yet significant deficits are exhibited in binocular depth perception and action. Importantly action in depth under binocular viewing may be a useful gross screening measure for stereodeficits in WS. Remediation of depth perception deficits in WS could train further understanding of monocular cues to compensate for poor stereopsis.
Research in developmental disabilities, 2014 · doi:10.1016/j.ridd.2014.04.013