Age-related deficits of manual grasping in a laboratory versus in an everyday-like setting

This study compared the grasping performance of 24 younger (20-30 years of age) and 24 older subjects (60-70 years of age) in a typical laboratory task (L) where movements were repetitive, externally triggered, purposeless and attention-attracting, and in an everydaylike task (E) where movements were part of a rich behavioral repertoire, internally initiated, purposive and little attended. We registered a wide range of kinematic and force parameters, and calculated their within-subject means and variation coefficients. Multiple differences emerged between the parameter values in L and E. Factor analysis reduced them to five independent effects. We also found multiple differences between the two age groups, with seniors responding more slowly and in a more stereotyped fashion. Multiple significant task x age interactions emerged as well, with age differences being more pronounced in E than in L. The latter finding is of practical relevance, since it suggests that age-related deficits in some real-life situations may be underestimated in laboratory research. It also is of theoretical relevance: it indicates that brain regions which are particularly vulnerable to aging may contribute to task E more than to task L.