Boeckhout, H.P. (2017) Exploration: Studying individual differences in learning a novel visuomotor reaching task. thesis, Human Movement Sciences.
Full text available on request.Abstract
Performing goal-directed actions requires coordinating the abundant degrees of freedom (DOF) in the many joints and muscles of the body. The aim of current study was to gain more insight in the formation of synergies, seen as task-specific functional units, to coordinate the abundant DOFs during learning a novel visuomotor reaching task. Individual changes during learning in end-effector and variability were investigated. Furthermore, the search strategy used to explore and assemble synergies was examined. Theorized blind (random search without use of previous experiences), local (systematic decrease in variability) and non-local (not continuous search in order to look over a higher volume of the region in same unit of time, supplemented by local search when a local minimum is found) search strategies were used to characterize the search strategy used. 15 participants performed reaching movements on a tablet to six different targets, containing 45° counter-clockwise rotated feedback. The uncontrolled manifold (UCM) method was used to quantify variability in variability leading to error (NGEV) and variability not influencing task performance (GEV). To characterize individual changes in performance change ratios, displaying mean performance of end trials divided by mean performance of begin trials (E/B), were computed to analyze magnitude of change in directional error (DE) after 150 ms, GEV and NGEV. To examine which search strategy was used, the distribution of the absolute difference with previous trial of DE, GEV and NGEV was analyzed on a single trial basis. Results showed that all participants learned and formed a new synergy. NGEV changed with the same magnitude as DE, while GEV did not. These results can be explained by the nature of the parameters. Decrease in DE and NGEV both cause an improvement in performance, while GEV does not necessarily improve performance. Change in GEV occurred in several participants and might be caused by constraints imposed by the body itself, such as avoiding fatigue or low energy expenditure. All participants showed non-linear or local search strategies, indicating local and non-local search strategies are used in the search for a synergy during learning a novel visuomotor reaching task Keywords Degrees of freedom, motor coordination, synergy, learning, exploration, uncontrolled manifold, movement solution, joint variability, visuomotor reaching task
| Item Type: | Thesis (UNSPECIFIED) |
|---|---|
| Supervisor name: | Bongers, dr. R.M. and Golenia, L. and Tuitert, I. |
| Faculty: | Medical Sciences |
| Date Deposited: | 04 May 2022 09:39 |
| Last Modified: | 04 May 2022 09:39 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/3223 |
Actions (login required)
 |
View Item |