Eye don't believe it

Abstract

The eyes might always have been the windows of the soul, but if the results of a recent study from Sweden by Mats Larsson and colleagues are to be believed, we could gain as much insight from studying the paintwork on the window-frames as from staring intently through the glass. Apparently eye colour has been associated with certain personality traits for some time: people with smouldering dark eyes are more likely to be extroverts, neurotics, or more easily emotionally aroused than those with steely blues. But the Swedish team have now gone one step further. They looked for associations between behavioural characteristics and the patterns of squiggles and dots that arise from variations in the thickness and density of the cell layers in the iris (Larsson M, Pedersen NL, Stattin H. Associations between iris characteristics and personality in adulthood. Biol Psychol 2007, available online Feb 1). By studying the irises (irides actually) of more than 400 university undergraduates, the researchers found that those with denser “crypt” structures (a result of less cell loss in the top two layers) tended to be “more receptive to their inner feelings”, “form warmer and more trustful attachments”, and “express positive emotions…more often” than those with open structures. Bonkers? Well, possibly. But there is a proposed mechanism for this rather far-fetched association, and it might just be plausible. The formation of crypts and other iris characteristics is thought to be influenced by the gene PAX6, which is also thought to affect personality traits via its ability to induce cell loss in an area of the brain associated with “approach-related” behaviours. One poor family with a mutation in PAX6 showed high rates of “disinhibition, impulsive behaviour…and impaired social understanding”. I bet their irides were a mess. So perhaps we all ought to watch out. Many of us know that heart-sinking feeling when confronted at interview by the dreaded psychometric test. But perhaps there will be no place for such time-consuming investigations in the near future. All a prospective employer might require before our inner workings are revealed is a decent digital camera and a crypt scale. Maybe we should all wear dark glasses to interviews from now on, just to be on the safe side. The psychoanalysts could have a field day with that.