Research shows why you should believe your eyes

(PhysOrg.com) -- Changes in a person's eyes can show that they've seen something before, even when they're pretending they haven't, research by University of Sussex doctoral student Becky Heaver reveals.

The research by Becky Heaver, presented today, (1 April 2009), at the British Psychological Society Annual Conference in Brighton, could be the key to exposing people who claim amnesia.

The research used eye-tracking techniques to compare the changes in pupil size during a recognition memory test. Participants were given a list of words to learn, and then presented with a test list that contained these 'old' learned words mixed up with an equal number of 'new' words.

Participants' pupils dilated significantly more when viewing 'old' words than when they viewed the 'new' words. Importantly, this difference in maximum pupil size also occurred when the same participants were asked to pretend they hadn't seen the words before and say 'new' to all words.

The findings suggest that the changes in pupil size are linked to the recognition memory process. This test may be able to distinguish people who are feigning amnesia from those with genuine memory impairments.

Becky Heaver says: "It's really interesting to find that pupils dilate more when people view previously learned items, even when they are pretending not to remember them. This could have implications for preventing fraudulent claims of feigning amnesia for financial reward."

Provided by University of Sussex