Sammendrag
In most daily activities the two hands work complementarily. Seemingly unimanual activities like writing also have contributions from the non-dominant hand (NDH) with observed actions such as stabilization and orientations of the paper. The present study investigated the impact of the different actions of the NDH in a pen-and-paper fine motor precision task. 41 right-handers and 12 left-handers performed a task that included drawing straight lines counterclockwise to connect 4 dots (100mm apart, placed in the four corners of a square tilted 45 degrees). Each participant was given the task in 4 conditions with varying constraints on the contribution of the NDH. The conditions were, 1. No NDH contribution, 2. NDH placement only, 3. NDH placement & paper orientation, and 4. Natural (Paper was fixed to the table in conditions 1 and 2, pen lift was allowed only in condition 4). Accuracy was measured as errors (Deviations from the straight lines in mm2). The participants had the best accuracy with the “Natural” condition, and it was significantly better than “No NDH contribution” and “NDH placement & paper orientation” in right-handers. The worst performance was in “NDH placement & paper orientation”. Left-handers were able to maintain similar accuracy across the conditions. The results indicate that participants preferred to use a bimanual strategy whenever possible. The strategy used and the type of bimanual coordination depends on the constraints imposed and handedness. Limiting the contribution of the NDH in pen-and-paper tasks does not affect the performance severely as adjustments are made to maintain accuracy.