A study found memory decline is associated with reduced visual exploration, demonstrated by a lack of variation in eye movements when viewing a series of different images.

Researchers in Canada and the West Indies including lead author Dr Jordana Wynn, Department of Psychology, University of Victoria, described investigating changes in naturalistic viewing behaviour across five participant groups spanning a broad spectrum of memory function, from healthy young adults to amnesic cases.

In the first experiment, participants viewed a series of 120 images for five seconds each across three blocks of 40 novel images. “Idiosyncratic gaze similarity was computed as the average correlation of eye movements for every image with eye movements for every other image viewed within the same block by the same participant. Low idiosyncratic gaze similarity reflected an encoding pattern that is unique to a particular image and high similarity reflected a generic pattern of encoding.”

The lowest idiosyncratic gaze similarity was found in the young adult group and was highest in the amnesia group, they wrote.

In the second experiment, half of the images were shown just once, with the other half shown three times each. Results showed healthy young adults encoded unique image features with each presentation, “thus building up a more comprehensive representation of each image in their memory”, while participants with decreased memory function tended to view the same image features with each presentation, said researchers.

“Memory decline is associated with an underlying reduction in explorative, adaptive and differentiated visual sampling of the environment. Our results provide compelling evidence that naturalistic gaze patterns can serve as a sensitive marker of cognitive decline.”

The study was published in Proceedings of the National Academy of Sciences.