Eye tracking reveals altered gaze characteristics in children with developmental coordination disorder

Research Digest

Neil M. Thomas & Kai Dierkes

February 16, 2021

The setup combines a motion capture system and a head-mounted Pupil Core eye tracker. Left: A child prior to descending the custom-built staircase. Right: Ego-centric point-of-view from the top of the staircase, where the white circle denotes a gaze point.

What is developmental coordination disorder?

Learning to autonomously move by crawling, walking, running and jumping is a developmental challenge for every child. Securely navigating the physical environment relies on the continuous integration of sensory information - such as visual cues - with careful planning and coordinated execution of body movements.

A number of children struggle with so-called developmental coordination disorder, a condition that negatively influences their coordination abilities. Affected children are often described as more clumsy than their typically developing peers. They experience an increased number of potentially harmful trips and, in particular, can be more prone to falling on stairs.

Assessing gaze during stair walking

In a recent study, researchers in the lab of Prof. Mark Hollands at Liverpool John Moores University compared the gaze strategies employed by children with and without developmental coordination disorder while walking down a staircase. The reported findings not only deepen our understanding of why children with developmental coordination disorder are more prone to falls. By informing tailored training programs for affected children, they are also likely to have direct implications for their quality of life.

For their study, the researchers utilised a custom-built staircase, combining a motion capture system and a head-mounted Pupil Core eye tracker (Figure 1). This dual setup enabled them to quantitatively relate gaze information with the current location of a child relative to the upper and lower end of the staircase. In particular, they could assess how many steps ahead children were looking while walking down the stairs.

Combining eye tracking and motion capture is technically challenging, not least on stairs. In order to be able to see the steps, people tend to adopt a large downward shift of gaze when walking down stairs. To accommodate for this, the researchers made use of Pupil Core’s freely adjustable scene and eye cameras to tailor the eye tracker specifically to each child. This ensured that during stair walking, both the steps and eyes remained visible in the world and eye cameras, respectively. In addition, they also leveraged the easy access provided by Pupil Capture to raw gaze-estimation data for synchronisation of the motion capture system and eye tracker.

Children with developmental coordination disorder show altered gaze characteristics

The central finding of the study is that children with developmental coordination disorder indeed employ a different gaze strategy as compared to their typically developing peers. More specifically, they tend to look further along the staircase, i.e. more steps ahead (see Figure 2). This result suggests that children with developmental coordination disorder prioritise visual sampling for future stepping actions, rather than immediate stepping constraints. The reported observations thus furnish a potential explanation for their increased numbers of falls. This finding will guide future research to understand if and how altered gaze behaviour influences the risk of falls, which will be crucial for informing falls prevention strategies and visual training programs.

Gaze allocation on the staircase
Figure 2. Gaze allocation on the staircase. A (left): Children with developmental coordination disorder looked further down the staircase than their typically developing peers. This suggests a prioritization of planning for future stepping actions. B (right): The difference in gaze allocation was statistically significant (*).

Our Comment

This novel application of Pupil Labs eye tracking has provided important insights into the walking behaviour of children with developmental coordination disorder. It is pleasing to see our equipment being used in research that has the potential to improve quality of life, and we look forward to future research from the group!

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Copyright: All figures reproduced from the original research articles published in Frontiers in Human Neuroscience under the commons attribution license (Attribution 4.0 International CC BY 4.0). Copyright holders: © 2020 Parr*, Foster, Wood, Thomas and Hollands. Figures cropped and resized for formatting purposes and captions and legends changed to align with the present article’s content. *j.parr@mmu.ac.uk