The pupils of someone with post-traumatic stress disorder (PTSD) display an exaggerated response when viewing exciting or dangerous images, a UK study has found.
Shocking or surprising images usually cause our pupils to enlarge, said co-author Nicola Gray, professor of psychology at Swansea University. “The pupil normally shows a fast constriction when a person sees a new image, but then gets bigger, especially if the picture is arousing, such as a scary image.” However, the PTSD patients behaved differently in both phases, she said. “First, their pupils did not constrict much when shown a new picture and then they expanded more to the scary images than for people without PTSD.”
The PTSD group’s pupils also enlarged in response to images which were positive and exciting, said co-author Professor Robert Snowden of Cardiff University. "The subjects weren't frightened by these images, but the images were arousing. Once again, the PTSD people showed a far greater response, indicating that they were even more aroused by these images than the other participants.”
The researchers said they hoped their findings could help with PTSD diagnosis and to develop new PTSD therapies.
The study was published by Biological Psychology.
