Wednesday, 24 August 2011

Performing and learning 90° in older adults

Despite a wealth of knowledge regarding coordinated rhythmic movements in a healthy population of adolescents and younger adults this is not the case for their older counterparts. Following a review of the minimal literature the understanding of older adult populations appears inconclusive. From reviewing the main two papers similarities between the elderly and young populations are present. Firstly the elderly possess the ability to perform 0° and 180° at relative ease with little to no difference to the younger populations. With both populations able to learn the least stable phase of 90° when exposed to specific training.
However this is where the similarities cease and the differences begin. Despite both groups fully understanding the movement demands of a 90° phase the ability to produce this is diminished in older adults. Firstly older adults are more sensitive to different feedback types than younger adults. For example older adults did not improve when using augmented terminal feedback when the younger adults did. Furthermore, older adults show a greater improvement and retention of 90° when using concurrent augmented feedback when compared to other feedback methods used during training. Additionally learning 90° occurs at a slower rate in older adults, with the elderly initially drawn to perform at 180°; consequently leading to higher error rates during learning 90° in older adults. These error rates exist in variable movement frequencies, amplitudes and reduced accuracy with a 70° variation from the desired movement patterns. Therefore 90° cannot be considered stable but does become more so throughout training. However, the performance difference between the younger participants and the elderly becomes more pronounced with training.
So with poor performance by the elderly present in both papers when compared to the younger participants the question is, why? This may be explained through exploration of the feedback methods. Throughout training both terminal and concurrent augmented feedback was provided using a Lissajous display. In both papers subjects were tested at baseline and post training with differing perceptual information available. They were exposed to normal visual conditions, no vision of the hands and augmented feedback. The greatest performance in retention tests within older adults occurred under augmented concurrent feedback conditions. This was coupled with no significant difference between the no vision of the hands and normal vision conditions. Consequently this suggests that the perception of 90° or the requisite movement information is impeded in older adults. However, in slight contradiction to this, Swinnen et al. (1998) suggest that augmented visual feedback yields greater stability in retention under normal visual conditions. This may still suggest that older adults have improved their perceptual ability and are more able to gain the required requisite information due to training with augmented visual feedback.
In conclusion, by increasing the perceptual information available to older adults, novel coordinated rhythmic movements can be learnt. This may not result in movement stability on a par with younger populations, but yields improved performance when the augmented feedback is removed. However the research remains inconclusive and underwhelming in its amount and requires greater exploration within older adults.
Swinnen, S.P., S.M.P. Verschueren., H. Bogaerts., N. Dounskaia. (1998). Age-related deficits in motor learning and differences in feedback processing during the production of a bimanual coordination pattern. Cognitive neuropsycholocy, 15(5), 439-466.
Wishart, L.R., T.D. Lee., S.J. Cunningham., J.E. Murdoch. (2002). Age-related differences and the role of augmented visual feedback in learning a bimanual coordination pattern. Acta psychological, 110, 247-263.

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