Second only to the heart, the eyes have perhaps been the body part that have most attracted the poets, the writers and the hopelessly romantic throughout history – Shakespeare referenced the eyes over 500 times in his writing (the heart more than double that, but the brain less than one hundred times). In literature, eyes can be hard- flinty, beautiful- soft, glowing, shimmering, seductive, glazed over, all knowing or dull, widened in terror or narrowed with suspicion. Famously, the eyes are the window to the soul (or window to the sole if you’re into iridology and reflexology?), and the currency of justice.
The pupil is a remarkable structure and David Butler recently wrote about the pupillary ruff – just one aspect of this amazing bit of anatomy. Your pupils will dilate when you look directly into the eyes of another, when you are aroused by another person, constrict when you are making a preference decision and dilate more in the presence of increased oxytocin. Dilated pupils will make you appear more attractive to the other sex and will increase amygdala activation in others looking into your eyes.
Some recent research has also found that pupils will dilate when you just think about bright or dark environments, as reported in Scientific American:
Pupils Dilate or Expand in Response to Mere Thoughts of Light or Dark
“Mechanical though they may be, the workings of pupils are allowing researchers to explore the parallels between imagination and perception. In a recent series of experiments, University of Oslo cognitive neuroscientists Bruno Laeng and Unni Sulutvedt began by displaying triangles of varying brightness on a computer screen while monitoring the pupils of the study volunteers. The subjects’ pupils widened for dark shapes and narrowed for bright ones, as expected. Next, participants were instructed to simply imagine the same triangles. Remarkably, their pupils constricted or dilated as if they had been staring at the actual shapes. Laeng and Sulutvedt saw the same pattern when they asked subjects to imagine more complex scenes, such as a sunny sky or a dark room.”
We know that imagined bodily movements activate much of the same brain regions as actual movements – Graded Motor Imagery uses this knowledge as the theoretical foundation of the programme. But the pupil response is not restricted to brain activity, thinking of a dark scene will create a measurable dilation of a person’s pupil. It’s not too great a jump to reason that pupils physically change to imagined illumination levels because we have no voluntary control over them – unlike our hands and feet that we can imagine moving but keep still. Perhaps this honesty lends the eyes their privileged place in the minds and writings of those poets and hopeless romantics.
At noigroup we actively support pain research in numerous ways. From promoting and raising the awareness of the research of our friends, contributing to, and assisting with research via our online tools such as Recognise™, and directly funding research. A proportion of all noigroup course fees and product sales goes directly to funding research that will make a difference in the lives of people experiencing persistent pain.
Reading through this, I am reminded of some research I did years ago using a home made pupillometer. I was seeing if the pupil responses were altered by posture. The subjects were allowed 20 minutes to relax and adapt to the dark so we could get a nice wide pupil of at least 6mm before I tested the light response.
For some, we could easily get a nice relaxed pupil, in others it was hard. I remember looking back over my results and it was quickly clear that the subjects who knew me best could easily relax their pupils and those who didn’t or were a bit suspicious were much harder.