Laterality across the lifespan: The effects of task complexity


The current study aimed to build on the work of Gooderham & Bryden (2013) by comparing the effects of task complexity on hand selection across the lifespan.  It was hypothesized that the increasing complexity of a task would override a biomechanically efficient movement such that participants would use only the preferred hand to complete the task.  It was also hypothesized that older adults would perform similarly to young children with respect to switch points in space.  Four age groups of participants (3-7 year olds, 8-12 year olds, 18-25 year olds and adults over 70 years) completed the newly designed Hand Selection Complexity Task (HSCT) which is an observational method designed to investigate the effects of task difficulty on hand selection in terms of Fitts’ Law.  The measures allows for the proximity of reaches to remain the same, while manipulating task difficulty. Participants also completed the Long Pegboard (Bryden, et al., 1994), which measured the behavioural preference of hand selection.  Finally, participants completed the Waterloo Handedness Questionnaire, to determine hand preference.  Results indicated that young children and older adults required an increased amount of time to complete the HSCT at all difficulty (ID) levels.  However, with respect to a complexity switch point, no significant differences were found between young adults and older adults indicating a similar performance.  Young children and adolescents preferred to switch to using their preferred hand to complete the task, regardless of spatial location.  Conversely, both the young and older adults utilized the hand in closest proximity to the task.  Results for the Long Pegboard task again indicated that young children and older adults required significantly more time to complete the task compared to the other two populations.  The results of this study will be discussed in light current theories of hand selection.