Reversal of Processing of Emotion Occurs in the Brains of Left-Handed Individuals


A study by Geoffrey Brookshire and Daniel Casasanto of The New School for Social Research in New York has shown that whether we are left-handed or right-handed can determine how our brains organise emotions.

Being right or left-handed affects how emotions are processed.

Various emotions make-up the human form and scientists have always suggested that emotions such as approach motivation are mainly processed in the left hemisphere of the brain and the right side of the brain gives rise to withdraw motivation. However in this study it has been suggested that these patterns are reversed in left-handed individuals compared with right-handed individuals.

In this study electroencephalography (EEG) was used to compare brain activity of the participants of the study at rest in both hemispheres of the brain. After the brain activity at rest was measured and noted, the participants were then asked to complete a questionnaire to measure the level of their approach motivation (an integral part of human personalities). The results showed that those that were right-handed had stronger approach motivation associated with higher levels of activity in the left hemisphere of their brains. It was then shown that unlike prior studies, those that were left-handed saw higher levels of activity in the right hemisphere associated with strong approach motivation.

Cognitive functions do not usually reverse dependent on whether an individual is left or right-handed but Casasanto said in relations to this study, “We predicted this hemispheric reversal because we observed that people tend to use different hands to perform approach-related and avoidance-related actions.”

This comes from observations that individuals will perform approach actions with their dominant hands, such as right-handed individuals would use their right hands for these actions and their non-dominant hand, their left hand for actions that were for avoidance.

The findings of this study could have further implications for treatments of such conditions as depression and anxiety disorders, which are traditionally treated with brain stimulation in the patient’s left hemisphere. This study however has shown that the approach actions that have been long associated with the left hemisphere differ between right and left-handed individuals and thus as Brookshire says, “this treatment, which helps right-handers, may be detrimental to left-handers, the exact opposite of what they need.” Therefore the findings of this study could lead to better and more efficient neural therapies for the treatments of these conditions.


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