Abstract
Despite the pervasive practice of repeated testing sessions, learning may be inherent due to repeated exposure; however limited research has examined the methodological implications of this phenomenon. Accordingly, ten healthy old adults (67±7 years) stood on a force plate for 30 s in feet apart (FA) and semi-tandem (ST) while completing simple reaction time (SRT) and choice reaction time (CRT) tasks. During the SRT trials, participants were asked to verbally respond “tie” to random high pitched auditory cues. During the CRT trials, participants were presented with low and high auditory stimuli and they were asked to respond “tow” and “tie”, respectively. The instructions were to stand as still as possible while verbally responding as fast as possible, when applicable. This protocol was repeated over a total of 5 sessions, each one week apart. Results showed a time effect for RT (p<0.001) such that RT progressively decreased over the 5 sessions (p<0.05). A time effect was also shown for center of pressure (COP) Path Length (p=0.017) and COP Velocity (p=0.023) as sway parameters progressively decreased over the 5 sessions (p<0.05). Unsurprisingly, ST tasks showed significantly longer RT as well as greater sway parameters compared to FA tasks for RT (p<0.001), Path Length (p<0.001), Velocity (p<0.001), COP Standard Deviation in the medial-lateral direction (p<0.001), and COP Area (p<0.001). These marked improvements in RT, Path Length and Velocity over time have important implications for interpreting data from interventions and other repeated assessments such as during balance training in a dual-task context. Notably, improvements in RT and standing posture demonstrated after repeated exposure to a dual-testing protocol may fully or partly be due to familiarization and learning effects as opposed to the intervention itself.
