New research by Welsh academics found that a patient's pupils may reveal whether they have suffered a traumatic experience. The study has been published in the journal Biological Psychology.

The study involved people living with post-traumatic stress disorder (PTSD), a condition that can happen in people who have witnessed or experienced a scary, shocking, or any traumatic event be it abuse, accident, or hijacking. 

The research team, led by Dr. Aimee McKinnon at Cardiff University, searched for signs of these traumatic events in the eyes study participants who were suffering from PTSD. The participants of the study were shown a series of images that portrayed pleasant, threatening, and neutral events. The team then measured the pupil of the participants' eyes based on the theme of a particular image.

Participants of the research include people with PTSD and people who had experienced trauma but were not living with PTSD.

The tests concluded with different results for two groups. The response of participants with PTSD was entirely different compared to those who did not have the condition. For those with PTSD, their pupils grew larger as a result of the emotional stimuli. 

The pupils of participants with PTSD were also found to show an exaggerated response to threatening stimuli. An unexpected result, however, was that the same result was found when they were shown "happy" or positive images, such as exciting sports scenes.

The research team believes this is an important finding.

"This shows that the hyper-response of the pupil is in response to any arousing stimulus, and not just threatening ones," said Professor Nicola Gray, co-author of the study. "This may allow us to use these positive pictures in therapy, rather than relying upon negative images, that can be quite upsetting to the patient, and therefore make therapy more acceptable and bearable.

Dr. McKinnon also explained that their findings could change current methods of treatment for PTSD, which mostly rely on fear-based stimuli. She made an emphasis on how this method could be a burden to the lives of patients with PTSD. 

With the new findings, it means that any kind of stimulation, so long as it triggers a high-level of emotion even if this is positive, that is enough to trigger the threat system. 

It is critical, therefore, for clinicians to understand the impact of positive stimuli in order to help treat patients in mental health institutions. This would help them better overcome the trauma they face.