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Project Summary
Ethics Approval Number:
2013/091
The Relationship Between the Hemispheric Polarity of Emotional Valence and Handedness
Project type:
4th Year Bachelor of Psychology / PgDip
Student Investigators: Ben Adler, Narelle Brown, Abbey Butcher, Graham Goodall-Smith, Hayley Gregson, Rachel Sam.
Supervisor: Dr Jeff Coney

At the moment there has been substantial research done on why humans display a hand preference when they are undertaking a task. Previous research has explained hand preference from the perspective of evolution, genetics, social pressure, a “right biased” world and a combination of an individual’s motor learning capacity and exposure to environmental bias. The purpose of this study was to investigate a new theory that links hand preference and positive feelings.

The study aimed to explore whether most people are right-handed rather than left-handed, because, as a young child, they were rewarded by more positive feeling when they use this hand as they are activating the left hemisphere of the brain. As an addition to this, we looked at left-handed people to see if they had a reversed emotional polarity across the brain, that is, they experience positive feelings when the right hemisphere is activated.

The current study involved 81 left- and right-handed, male and female, adult participants completing a computer-based word recognition and face recognition task. The word task contained both words and non-words. The words were positive, neutral or negative. The participants were asked to fixate on a black cross that was centrally displayed on a screen, with a word presented immediately after to either the left or right visual field. The participants then had to make a “go” or “no go” judgement for the word task based on whether it was a word or not. Reaction times and error rates were recorded. The same was done for the face task, however, the only difference being that the faces were only either positive or negative and the participant had to make a choice (forced choice procedure).

The results of the study indicated a significant difference in the processing of negative emotions between the two hemispheres of left-handed and right-handed people. The left hemisphere in left-handed people and the right hemisphere in right-handed people was more oriented toward the recognition of negative emotion. (The processing of positive emotions between the two hemispheres of left-handed and right-handed people, however, did not show any significant difference). This is quite a ground breaking discovery! It suggests that it is negative aversion, rather than positive inducement, that is the main driver behind the development of hand preference in humans. For most children, using the right-hand would only generate fairly neutral emotions, whilst using the left hand would generate negative emotions, so they develop a long-term aversion to their left-hand, and subsequently use their right. In left-handed people the opposite is found. Further research that used an electrophysiological approach to our study could provide stronger support to our finding.