There Are Many Myths About Left-Handed Brains. Here is What We Really Know

There have been loads of claims about what being left-handed means, and whether or not it adjustments the kind of individual somebody is – however the reality is one thing of an enigma. Myths about handedness seem yr after yr, however researchers have but to uncover all of what it means to be left-handed.

So why are folks left-handed? The reality is we do not absolutely know that both. What we do know is that solely round 10 % of individuals the world over are left-handed – however this is not cut up equally between the sexes. About 12 % of males are left-handed however solely about eight % of girls. Some folks get very excited in regards to the 90:10 cut up and marvel why we aren’t all right-handed.

However the attention-grabbing query is, why is not our handedness primarily based on probability? Why is not it a 50:50 cut up?

It’s not resulting from handwriting course, as left-handedness could be dominant in international locations the place their languages are written proper to left, which it’s not the case. Even the genetics are odd – solely about 25 % of kids who’ve two left-handed mother and father will even be left-handed.

Being left-handed has been linked with all types of unhealthy issues. Poor well being and early loss of life are sometimes related, for instance – however neither are precisely true.

The latter is defined by many individuals in older generations being pressured to modify and use their proper arms. This makes it seem like there are much less left-handers at older ages. The previous, regardless of being an interesting headline, is simply improper.

Optimistic myths are additionally abound. Individuals say that left-handers are extra artistic, as most of them use their “proper mind”. That is maybe one of many extra persistent myths about handedness and the mind.

However irrespective of how interesting (and maybe to the frustration of these lefties nonetheless ready to get up in the future with the skills of Leonardo da Vinci), the overall concept that any of us use a “dominant mind facet” that defines our character and determination making can also be improper.

Mind lateralisation and handedness

It’s true, nevertheless, that the mind’s proper hemisphere controls the left facet of the physique, and the left hemisphere the correct facet – and that the hemispheres do even have specialities. For instance, language is normally processed just a little bit extra inside the left hemisphere, and recognition of faces just a little bit extra inside the correct hemisphere.

This concept that every hemisphere is specialised for some abilities is named mind lateralisation. Nonetheless, the halves don’t work in isolation, as a thick band of nerve fibres – referred to as the corpus callosum – connects the 2 sides.

Apparently, there are some recognized variations in these specialities between right-handers and left-handers. For instance, it’s typically cited that round 95 % of right-handers are “left hemisphere dominant”.

This isn’t the identical because the “left mind” declare above, it truly refers back to the early discovering that almost all right-handers rely extra on the left hemisphere for speech and language. It was assumed that the other could be true for lefties.

However this isn’t the case. The truth is, 70 % of left-handers additionally course of language extra within the left hemisphere. Why this quantity is decrease, somewhat than reversed, is as but unknown.

Researchers have discovered many different mind specialities, or “asymmetries” along with language. Many of those are specialised in the correct hemisphere – in most right-handers at the least – and embody issues reminiscent of face processing, spatial abilities and notion of feelings.

However these are understudied, maybe as a result of scientists have incorrectly assumed that all of them depend upon being within the hemisphere that is not dominant for language in every individual.

The truth is, this assumption, plus the popularity small variety of left-handers have uncommon proper hemisphere mind dominance for language, means left-handers are both ignored – or worse, actively averted – in lots of research of the mind, as a result of researchers assume that, as with language, all different asymmetries will probably be decreased.

How a few of these capabilities are lateralised (specialised) within the mind can truly affect how we understand issues and so might be studied utilizing easy notion assessments. For instance, in my analysis group’s current research, we offered footage of faces that have been constructed in order that one half of the face exhibits one emotion, whereas the opposite half exhibits a special emotion, to numerous right-handers and left-handers.

Often, folks see the emotion proven on the left facet of the face, and that is believed to mirror specialisation in the correct hemisphere. That is linked to the truth that visible fields are processed in such a manner there’s a bias to the left facet of house.

That is thought to signify proper hemisphere processing whereas a bias to the correct facet of house is believed to signify left hemisphere processing. We additionally offered various kinds of footage and sounds, to look at a number of different specialisations.

Our findings counsel that some varieties of specialisations, together with processing of faces, do appear to comply with the attention-grabbing sample seen for language (that’s, extra of the left-handers appeared to have a desire for the emotion proven on the correct facet of the face).

However in one other process that checked out biases in what we take note of, we discovered no variations within the brain-processing patterns for right-handers and left-handers. This consequence means that whereas there are relationships between handedness and a few of the mind’s specialisations, there aren’t for others.

Left-handers are completely central to new experiments like this, however not simply because they will help us perceive what makes this minority totally different. Studying what makes left-handers totally different may additionally assist us lastly remedy most of the long-standing neuropsychological mysteries of the mind.

Emma Karlsson, Postdoctoral researcher in Cognitive Neuroscience, Bangor College.

This text is republished from The Dialog beneath a Inventive Commons license. Learn the unique article.