Investigating age-related differences in visual sampling behaviour during adaptive locomotion and their consequences for stepping accuracy

Abstract

Older adults at a high-risk of falling (HROA) look away prematurely from targets they are stepping on in order to fixate future constraints in their walking path. This gaze behaviour is associated with decreased stepping accuracy. The first aim of this thesis was to investigate a possible causal link between premature redirection of gaze from a target and reduced stepping accuracy. Results showed that when older adults voluntarily delayed gaze transfer from a target, their foot placement showed greater accuracy and consistency. Secondly, we investigated a possible relationship between increased anxiety about upcoming obstacles and early gaze transfers away from an initial target. We found that progressively increasing task complexity resulted in associated increases in anxiety, extent of early gaze transfers and stepping inaccuracies in HROA. Finally, we investigated the extent to which young, low-risk older adults and HROA can perform visually guided online alterations to foot trajectory during the swing phase towards a target. We found that adjustments made by older adults (specifically HROA) were characterised by increased latencies and reduced magnitude. We suggest that age- and fall-risk related differences in strategies governing visual sampling and the allocation of attention during adaptive locomotion contribute to incidences of elderly falls