The eyes are a window to the soul, so the proverb goes. Perhaps we shouldn't be surprised then that psychologists have reported characteristics of the human iris, the coloured part of the eye, correlate with aspects of personality.
Mats Larsson and colleagues compared the thickness and density of the iris in 428 participants with aspects of their personality as measured by questionnaire. They found participants who had more features called Fuchs' crypts on the surface layers of their iris (reflecting thicker tissue) tended to form warmer and more trustful attachments to other people, and experienced more positive emotions. Meanwhile, participants with more 'contraction furrows', another indicator of tissue density, tended to have more impulsive personalities. No association between eye colour and personality was found.
The researchers think the basis of the association between the iris and personality lies with the Pax6 gene, which is linked with tissue growth both in the iris and the brain. Specifically, Pax6 is implicated in development of the anterior cingulate cortex, a brain region involved in positive emotion and self-control.
“These findings support the notion that people with different iris configurations tend to develop along different trajectories in regards to their personalities”, the researchers said.
Larsson, M., Pederson, N.L. & Stattin, H. (2007). Associations between iris characteristics and personality in adulthood. Biological Psychology, In Press.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.