A new study tries to find out why a majority of us - 90 pc - are biased towards using our right hand than left.
Researchers from the University of Aberdeen, UK, believe the explanation may stem from actions that require us to use both hands at the same time, which may bias right-handers toward choosing their right hands.
For the study, the team asked left- and right-handed participants 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.
Just before they began the reach, subjects were given a short vibratory pulse on one of their hands, giving them a clue about where the new target would appear, and hence which hand should perform this second portion of the reach.
In some cases, the pulse was given to the wrong hand, which meant that subjects had to restrain the reach with this incorrectly-cued hand.
Results showed that right-handed volunteers found it far more difficult to deal with this incorrect cue when it was given to their right hands, making more mistakes and taking 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 showed no such asymmetries, suggesting that they are less inherently biased to select one hand over the other.
"One explanation for these data is that hand choice is related to hemispheric specialisation for speech and language" said Dr. David Carey at the University of Western Ontario in Canada.
"Many left-handed people have "right-handed" brains, which weakens the typical bias towards choosing their dominant left hand."
The study appears in the April 2011 issue of Elsevier's Cortex.