The pupils in your eyes can reveal your traumatic past
The research, led by Dr Aimee McKinnon at Cardiff University and published in the journal Biological Psychology, looked for traces of traumatic events in the eyes of patients who were suffering from post-traumatic stress disorder (PTSD).
This was done by measuring the pupil of the eye while participants were shown threatening images such as vicious animals or weapons, as well as other images that showed neutral events, or even pleasant images.
The response of people with PTSD was different from other people, including people who had been traumatised but did not have PTSD.
At first the pupil failed to show the normal sharp constriction caused by changes in light levels, but their pupils grew even larger to the emotional stimuli than for the other participants.
A surprise finding
Another unexpected result, the researchers said, was that pupils of patients with PTSD not only showed the exaggerated response to threatening stimuli, but also to stimuli that depicted “positive” images, such as exciting sports scenes.
Swansea University’s Professor Nicola Gray, who co-authored the paper, believes it to be an important finding.
“This shows that the hyper-response of the pupil is in response to any arousing stimulus, and not just threatening ones. This may allow us to use these positive pictures in therapy and make therapy more acceptable and bearable.”
“This idea now needs testing empirically before it is put into clinical practice,” the researchers said.
The pupils and PTSD
Dr McKinnon added: “These findings allow us to understand that people with PTSD are automatically primed for threat and fear responses in any uncertain emotional context, and to consider what a burden this must be to them in everyday life.”
“It also suggests that it is important for us to recognise that, in therapy, it is not just the fear-based stimuli that need deliberate re-appraising.”
She noted that “clinicians need to understand this impact of positive stimuli in order to support their service-users overcome the significant challenges they face.”
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