Cognitive-motor interference describes the decrement in performance of tasks performed concurrently in the cognitive and physical domains. The overall aim of this thesis was to investigate the role of vision in cognitive-motor interference during locomotion. A further aim was to investigate the interference patterns between the performance domains during locomotion and consider the theories of neural reuse and executive functions as components in building a plausible explanation for such interference. 10 to 24 participants were recruited for five studies and asked to perform a range of physical domain tasks (repeated shuttle walks; continuous walking along a figure-of-eight path; and walking onto a public escalator) and cognitive domain tasks (working memory: serial seven subtractions and alphabetic recall). These were used to manipulate task demands in the physical and cognitive domains. Behavioural performance variables were captured across the physical, cognitive, and visual domains using a combination of motion capture, accelerometery, mobile eye-tracking, and audio recordings. Key findings showed that a concurrent working memory task caused a ~20% reduction in walking velocity. Furthermore, gaze orientation towards the walking path when walking at fast pace, decreased from 86% to 45% due to the inclusion of a concurrent working memory task. Additionally, gaze behaviours were also vulnerable to interference from an intermittent exogenous cue to switch cognitive tasks with gaze oriented towards the walking path for 31% of the task switch period compared with 42% for the remainder of the trial. However, during an escalator walking trial gaze was not averted from the task relevant areas. Instead, performance in the cognitive domain was poorer with a 1.83 second increase in working memory task response intervals during transition onto the escalator compared to the performance over the following four intervals. These findings suggest vision plays a central role in cognitive-motor interference as an important factor of the locomotor system that is especially vulnerable to interference from the cognitive domain. Reduced performance in the physical domain with a concurrent cognitive task may even be an adaptation to accommodate decrements in visual domain performance. Further, a predominantly one-way interference pattern is observed where the cognitive domain is resilient to cross-domain interference. However, this predominantly one-way interference pattern is reversed where spatial and temporal accuracy is required in the walking task resulting in compromised cognitive performance. The theory of Neural Reuse and the development of the Executive Functions may provide a framework to predict which domains interfere with each other and further research is required to investigate this. The dynamic inversion of the direction of cross-domain interference is a particularly interesting finding and more research is required to facilitate proper interpretation of this finding due to the large number of potential confounding factors in interference direction.
Evaluating cognitive-motor interference during human locomotion
O'Reilly, L. C. (Author). Sept 2021
Student thesis: Doctoral Thesis