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and Both (1989) found that blue-eyed children in kindergarten and Grade 2 were overrepresented in groups of extremely withdrawn youngsters, whereas no association could be found in Grade 4 or between eye color and extreme sociability in any grade.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’.
Link to BBC News story “How irises ‘reveal personalities'”.
Link to Living the Scientific Life post.
Link to Larsson’s page on his research.
Mind Hacks 
I used to date a woman who was quite adept with some practices of iridology:
http://en.wikipedia.org/wiki/Iridology
It seems to hold true to some of the scientific discoveries coming about in this field. I can’t claim that it’s accurate, but perhaps holds some clues to point the way for further research so that the two fields can corroborate to learn from one another.
This research is both impressive and disconcerting. While it is not surprising that personality is, at least in part, genetic, it is unbelievable and exciting that the irises more or less map out the personality. Mostly, it makes me wonder how such technology will be used in the future, and what its purpose is. Your comment that ‚Äúthe UK government wants to encode iris information on passports and keep copies on database to use in iris recognition systems‚Äù seems like a violation of privacy and is reminiscent of the futuristic movie Minority Report, in which eye scanning is used by both the government and by advertisers to identify and target individuals. I could even see eye scanning being used to screen applicants‚Äô personalities for jobs. Lastly, I am unclear about a couple of concepts. You cited other similar studies that looked into the relationship between personality and color, which ‚Äúfail to replicate the personality findings, typically because the effect tends to fade after early childhood.‚Äù Is Larsson’s research primarily different and more successful because it is applicable in adults? If so, since personality is not stable, do our irises change with new personality developments? Hopefully, if this technique is used on younger children it will not lead to a self-fulfilling prophecy from parents!
I find this very fascinating. This almost seems like it should be expected, the eyes, a person’s outlet to view the world, should serve the opposite purpose right? looking into them, should too, reveal some sort of deeper information about the person that cannot be on the outside. Perhaps that is why it is said that cops look for movements in the eye to determine lies. Or why some people find confessions to be more meaningful when one looks them in the eyes. The crypts, pigment dots, and furrows of the iris psychologist have been looking at almost take the form of a ”vortex” like those seen in science fiction portrayals that lead to other dimensions, in this case to a person’s traits. I would however, like to pose a question that may not yet have an answer. Professor Humayan at the University of Southern California has been for some years now working on restoring vision through the implanting of a bionic eye. He recently received permission by the FDA to conduct an exploratory patient trial on about 50-75 patients. I wonder what kind of information these bionic eyes would reveal about a person, and if in the near future, airports begin to use eye scans to identify people like you mentioned, how this would affect those with implants.
The whole ‘eye’ thing is strange, and honestly makes me believe in a God- because I feel like I’ve changed a lot over this last year, and my eyes seemed to have changed with me. Like, I used to have a grey-brown-green combination, like my Mum, but now i have this deep brown thing, and it generally looks a lot brighter, and warmer and stuff. And when I’ve seen a friend in shock, her eyes looked completely different to normal, like all…well…shocked! Hehe, incase you’re asking, it was just an exam, and she’s perfectly fine now. But yeah, I’ve met people with fear in their eyes, strength in their eyes, love in their eyes, hope in their eyes, general beauty in their eyes… and it’s a literal thing! You can literally see it! God knows, how though- very clever stuff. Very clever. 🙂 God bless to all you scientist people xx 🙂