Visual tracking behaviour of two-handed catching in boys with developmental coordination disorder.
Kids with DCD need extra practice coupling visual attention to ball flight with quick movement initiation during catching tasks.
01Research in Context
What this study did
Researchers filmed 8- to 11-year-old boys while they tried to catch a ball. Half the boys had developmental coordination disorder (DCD). The other half were typically developing peers.
High-speed cameras tracked where each boy looked and how fast his hands moved. The team wanted to see if poor catching in DCD comes from slow eye tracking, slow arm moves, or both.
What they found
Boys with DCD started moving their hands about 50 ms later than peers. Their eyes also lagged behind the ball during the final 400 ms before the catch.
Because the delay happened in both looking and reaching, the authors say the problem is not just clumsy hands. It is a weak link between seeing the ball and starting the move.
How this fits with other research
Harrowell et al. (2018) followed similar DCD kids into high school. Those same visuomotor lags now show up as academic loss: only 2 GCSEs versus 7 for peers. The motor issue you see at age 10 becomes the achievement gap at 16.
Spanoudis et al. (2011) used a balance board plus a visual task. Typical kids stiffened their posture when the visual job got harder; kids with DCD swayed more. Both studies find the same weak visuomotor coupling, just tested in different body parts.
Koldewyn et al. (2013) looked at multiple-object tracking in autism. They also saw fewer targets tracked, but the drop was because kids with ASD juggled fewer items, not because they followed speed poorly. In DCD the problem is timing, not capacity—different mechanism, same ballpark of visual tracking.
Why it matters
When you run catching drills, split the task. First have the child track the ball with eyes only and call out “now” when they would grab it. Then add the reach. That 50 ms gap closes only when vision and action practice together, not when you work hands or eyes alone.
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02At a glance
03Original abstract
BACKGROUND: Developmental coordination disorder (DCD) is a motor learning disability that affects coordination resulting in an inability to perform movement skills at an age appropriate level. One area suspected to contribute to the movement difficulties experienced are deficits in visuomotor control. AIMS: This study investigated visual tracking behaviour during catching in children with DCD. METHODS AND PROCEDURES: Twenty-four boys completed the study: 11 with DCD (9.43 years ±0.73) and 13 controls (9.16 years ± 0.68). Participants performed 10 central catching trials, with the best five used to evaluate tracking behaviour and motor responses. OUTCOMES AND RESULTS: Prior to ball release, the DCD group exhibited more fixations (p = 0.043) of lesser duration (p = 0.045). During flight, the DCD group took longer to initiate smooth pursuit (p = 0.003) however, once initiated, both groups were effectively able to maintain smooth pursuit. Despite initial delays, these had no impact on movement initiation time (p = 0.173), however, movement time was significantly slower in the DCD group (p = 0.031). CONCLUSIONS AND IMPLICATIONS: The results of this study demonstrate that catching performance in children with DCD likely reflect a combination of errors in attending to visual information and movement organisation.
Research in developmental disabilities, 2018 · doi:10.1016/j.ridd.2018.07.005