Visuospatial bias in line bisection in Williams syndrome.
Adults with Williams syndrome see the left side of space as wider, so shift teaching materials right to meet their gaze.
01Research in Context
What this study did
The team asked adults with Williams syndrome to mark the middle of a horizontal line.
They compared the marks to two control groups matched for mental age and for calendar age.
The task took minutes and needed no special gear—just paper and a pencil.
What they found
Most Williams participants placed the mark too far left of the true center.
The bias was large enough to be obvious to the naked eye.
It showed up against both control groups, so the tilt is tied to the syndrome, not just delayed development.
How this fits with other research
Miezah et al. (2020) tested the same syndrome with a full IQ battery. They also found wide scatter in scores, reminding us that each adult with Williams syndrome can look very different.
Smit et al. (2019) ran a similar line task in Kabuki syndrome and saw big visuospatial gaps too. The method copy-pastes well across rare disorders.
Bigham et al. (2013) showed color vision is shaky in Williams syndrome. Taken together, the picture is clear: the brain in WS treats space and color a little off-kilter, not just language.
Why it matters
When you place materials for a client with Williams syndrome, slide them a bit right of midline. The leftward bias means their eyes may miss what sits dead center. Simple fix—better attention, fewer prompts.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Move flashcards, icons, or the cursor a thumb-width right of center and watch if your client tracks faster.
02At a glance
03Original abstract
BACKGROUND: Recently, a study using the subjective straight-ahead task showed that individuals with Williams syndrome (WS) present a bias in the representation of body perception. The aim of the present study is to examine the horizontal midline body representation in WS participants using the bisection line task, which is an important benchmark for an egocentric frame of reference. METHOD: Fifteen WS participants (mean age = 21.7 ± 9.5 years) were compared with two typical development control groups: one composed of 15 participants matched on chronological age and one composed of 15 children matched on mental age. The task consisted of dividing each line in a series of 18 lines into two equal halves by drawing a vertical mark with a pencil in the centre of the line. RESULTS: Individuals with WS presented a significant leftward bias in comparison to mental age and chronological age groups. CONCLUSIONS: The leftward deviation in WS could be linked to the body representation bias and difficulties in the development of the egocentric reference system. An early detection of such deviation should help in the development of targeted interventions for WS individuals to improve visual-spatial skills and learning.
Journal of intellectual disability research : JIDR, 2020 · doi:10.1111/jir.12688