Elsevier Logo Ever thought why two cerebral hemispheres and motor cortices are not equally skilled with both hands? Well, the following tidbit seems to have figured out the reason behind this complication. A latest study from the University of Aberdeen suggests that right-handers are biased to choose their dominant hands for performing most skilled tasks.

During the study, left- and right-handed participants were asked to reach first toward a pair of targets with both hands at the same time and immediately afterwards, toward a new single target with only their closest hand. Experts gave the subjects a short vibratory pulse just before they began the reach. The pulse was given on one of their hands, so they were offered a clue about where the new target would appear, and hence which hand should perform this second portion of the reach.

In a small proportion of trials, the pulse was also given to the wrong hand, which meant that subjects had to restrain the reach with this incorrectly-cued hand in order to make the reach with the correct hand. Gavin Buckingham, a postdoctoral researcher at the Centre for Brain and Mind at the University of Western Ontario in Canada, and colleagues noted that right-handed subjects had far greater trouble dealing with this incorrect cue when it was given to their right hands.

So right-handers possibly ended up making more mistakes and took longer to successfully inhibit the reaches, almost as if the right hand was already pre-selected to carry on during the bimanual reach. The left-handed subjects reportedly had no such asymmetries. Hence, they appeared less inherently biased to select one hand over the other. In conclusion, it was asserted that right-handers have their attention largely directed at their right hands during bimanual tasks.

The study will be published in the April 2011 issue of Elsevier’s Cortex.