Tuesday, 23 January 2007

We become more ambidextrous as we get older

We’re unaware of it, but starting in middle-age, our dominant hand gradually loses its superiority, so that we become, in a sense, more ambidextrous as we get older.

Tobias Kalisch and colleagues recruited 60 participants who were all strongly right-handed according to the commonly-used Edinburgh Handedness Inventory (EHI), which asks people to indicate their favoured hand for several everyday activities. The participants then completed a range of computerised dexterity tests, including line tracing, an aiming task, and tapping (pictured left).

Consistent with their claims of right-handedness, the younger group of participants (average age 25 years) performed far better with their right hand on all the dexterity tests. By contrast, the middle-aged group (average age 50) performed just as well with either hand on the aiming task. And the two older groups (average age 70 and 80 years) performed just as well with either hand on all the tasks bar one.

Overall, performance tended to be poorer with increasing age, especially for the right hand. In other words, it seems we become more ambidextrous as we get older because our dominant hand loses its superior dexterity and becomes more like our weaker hand.

The findings were supported by a second experiment that used a gadget to record several hours of everyday hand use among 36 right-handed participants. The younger participants used their right hand far more than their left, whereas the older participants used both their hands a similar amount, despite claiming to be right-handed.

Neurophysiological studies don’t support the idea that one side of the brain ages more quickly than the other, so the researchers favour a “use-dependent plasticity” explanation for why our dominant hand loses its superiority. They said the dominance of our favoured hand is intensified through our use of it in everyday activities, so “when these activities decrease after retirement, or by the limitations in older age and sedentary lifestyles, it is conceivable that the practice-based superior performance of the right hand is no longer maintained…”.
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Kalisch, T., Wilimzig, C., Kleibel, N., Tegenthoff, M. & Dinse, H.R. (2006). Age-related attenuation of dominant hand superiority. PLoS ONE, 1, 1-9. (Open access).

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

6 comments:

  1. Anonymous1:04 am

    Curious.

    About 30 years ago I realized I used my right hand for just about everything, with my left only attending, so to speak.

    A friend learned to be ambidextrous so that he could operate a tenkey with his weak hand and write figures with his strong hand.

    It occurred to me my left hand was not so dumb after all, as it did half the work in touch-typing.

    Since then I have been teaching my left hand to get better at things.

    I use the left for the mouse since the standard computer keyboard is made for lefties. (It's amazing how many righties don't know this.)

    People who work with their hands -- carpenters, builders, masons, machine operators -- learn to get skilled at precision with both hands.

    Was intent taken into consideration in this study?

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  2. I don't think intent as such was taken into account. Participants were deliberately selected on the basis that they believed themselves to be strongly right-handed. So the key thing is that the older participants thought they were strongly right-handed but their performance with each hand had actually become equivalent. The full-text of the article is free to access so you could take a closer look if interested.

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  3. Testing someone's left hand for dexterity must be pretty simple: "Ummm...Nope".

    Oh, or did you mean skilled?

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  4. I was using the term 'dexterity' to mean 'skill and ease in using the hands'. Sorry for the confusion - I didn't realise you and the other person who still interprets 'dexterity' to mean 'right-handedness' would be reading the Digest.

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  5. :-) I was reading it one-eyed

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  6. Anonymous1:20 am

    I started playing tennis with my left hand after my right was injured. It was weird at first, but then started feeling more natural after a few weeks. I think maybe we just judge that initial awkwardness as an inability to do something -- but after investing some practice, we can actually fine tune the skill.

    ReplyDelete

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