Most people show a slight bias to the left-hand side of space. In other words, presented with a horizontal line and asked to identify its midway point, most of us will mark a position slightly too far to the left. Increasingly, however, research is showing that individuals vary in the side of space to which they are biased – a minority are biased to the right. What’s more, our spatial bias could be tied in intriguing ways to our personality type.
Rachel Tomer used the sensitive grey scales task to test the spatial bias of 56 undergraduates. (Participants were presented with several pairs of rectangles that fade from black to white in opposite directions. Their aim was to say which rectangle in each pair contains the most black).
Tomer found the usual overall bias to the left-hand side of space, but also discovered that ten participants showed a bias to the right. Intriguingly, she found that the students with the rightward bias also tended to score higher on a measure of novelty seeking – a proclivity to look for thrills and new rewarding experiences.
This link isn’t as surprising as it sounds considering research on animals shows their attentional bias is influenced by which side of their brain has the more active dopamine system (more dopamine activity in the left-hand hemisphere directs a bias to the right). Dopamine, of course, is a neurotransmitter known to be involved in pleasure and reward.
Tomer’s theory is that students with a bias to the right have more dopamine activity in the left of their brain, a characteristic also underlying their novelty seeking. But why, you might fairly ask, is it greater dopamine activity specifically in the left side of the brain that is linked with novelty seeking?
The answer isn’t entirely clear, but other lines of evidence also point to a link between left-sided dopamine activity and novelty seeking. For example, patients with Parkinson’s disease who exhibited dopamine loss in their left hemisphere showed a reduction in their novelty seeking habits, whereas similar patients with dopamine loss in their right hemisphere showed no such behavioural change. Moreover, an earlier brain imaging study by Tomer showed that healthy individuals with more dopamine receptors in their left vs. their right hemispheres reported being more motivated by incentives.
TOMER, R. (2008). Attentional bias as trait: Correlations with novelty seeking. Neuropsychologia, 46(7), 2064-2070. DOI: 10.1016/j.neuropsychologia.2008.02.005
Has this stirred your interest? Previously in the Digest:
The link between line bisection accuracy and emotional sensitivity to art.
How spatial biases could be distorting survey results.
And how tiredness affects our spatial bias.