The iris is the window to the soul
A fascinating paper just released online suggests that patterns in the iris of the eye can give an indication of personality.
The research has been led by psychologist Mats Larsson and looks at relationship between measures of personality and the ‘crypts, pigment dots, and contraction furrows’ of the iris.
BBC News covers the research, as does a post on the Living the Scientific Life blog. There’s also some excellent background material to the research on a page from Larsson himself.
The paper itself is only available to subscribers to Biological Psychology. It seems the free summary isn’t available online yet, but this is an interesting excerpt from the introduction of the paper on previous studies:
The idea that personality differences are related to iris characteristics is not new. In 1965, Cattell observed differences in cognitive styles between blue and brown eyed subjects (Cattell, 1965) and since then eye color has been found to be related to a great variety of physiological and behavioral characteristics. Dark eyed people have on average higher scores on extraversion, neuroticism (Gentry et al., 1985), ease of emotional arousal (Markle, 1976) and sociability (Gary and Glover, 1976). However, there are a number of studies that fail to replicate the personality findings, typically because the effect tends to fade after early childhood. For instance, Rubin and Both (1989) found that blue-eyed children in kindergarten and Grade 2 were overrepresented in groups of extremely withdrawn youngsters, whereas no association could be found in Grade 4 or between eye color and extreme sociability in any grade.
According to Larsson’s more recent research, a gene called Pax6 is involved in both the development of the eye, and the development of an area of the frontal lobe called the anterior cingulate cortex or ACC.
The ACC is known to be involved in attention and inhibiting automatic responses, and there’s plenty of evidence to link it to personality-relevant traits like empathy and self-control.
Larsson found that ‘crypts’ were significantly associated with five personality characteristics (Feelings, Tendermindedness, Warmth, Trust and Positive Emotions) whereas ‘contraction furrows’ were associated with Impulsiveness.
I can’t say I’m entirely clear what ‘crypts’ and ‘contraction furrows’ look like, but there’s a description on Wikipedia and you can click here to see the diagram from Larsson’s paper in a popup window.
If it comes as a surprise that the same gene could influence both the eye and brain development, it’s actually not that strange an idea based on what we already know.
The retina, like the brain, is part of the central nervous system, so genes that code for the eye could also be associated with brain development.
Furthermore, the face develops from some of the same cells as the brain during the early stages of embryo growth.
This is why disorders that cause learning disabilities are sometimes associated with distinctive facial features (e.g. Down syndrome, Williams syndrome).
One other recent development worthy of note is that governments and businesses are now set on storing iris information to use as ID.
For example, the UK government wants to encode iris information on passports and keep copies on database to use in iris recognition systems in a system that is being trialled at the moment.
This might mean that personality profiles could be generated from biometric data.
How accurate they might be remains another question, but as with any centralised population sample, the concern is that those with unusual results may be scrutinised more closely using other methods, or deemed to be ‘risky’.