Eye movements could help tracking memory of individuals more efficiently than behavioural reports alone, a new study has revealed.
According to the study, tracking where and for how long a person focuses his or her eyes ‘can distinguish previously seen from novel materials even when behavioural reports fail to do so’.
"Eye movements are drawn quickly to remembered objects," said Deborah Hannula, assistant professor at the University of Wisconsin Milwaukee.
The researchers gave university students 36 faces to study. These target faces were also morphed to produce images closely resembling them; the morphed phases were not seen during the study phase. The students were then shown 36 three-face displays, one at a time.
Told that the studied faces wouldn’t always be there, the participants had to press a button indicating which face was the studied one, or simply choose a face if they felt none had been studied. They then reported verbally whether the studied target face was present or not.
While they looked at the 3-face display, their eye movements were recorded, tracking where the eyes focused first and what proportion of time was spent looking there. For the analysis, the psychologists divided the faces into three groups: studied targets; morphs mistaken for the "target" face; and morphs chosen and known to be incorrect.
Participants easily identified the target faces most of the time. They also spent more time looking at these faces, and did so soon after the 3-face display had been presented.
"The really interesting finding is that before they chose a face and pressed a button, there was disproportionate viewing of the target faces as compared to either type of selected face," said Hannula.
However, "after the response was made, viewing tended to mimic the behavioural endorsement of a face as studied or not, whether that endorsement was correct or incorrect."
In other words, "pre-response viewing seems to reflect actual experience, and post-response viewing seems to reflect the decision making process and whether or not the face will be endorsed as studied."
Apart from the potential for practical application, eye movement methods could be used to examine memory in individuals—like some psychiatric patients and children – who may have trouble communicating what it is that they remember.
“Eye movements might provide us with more information about what exactly these individuals remember than behavioural reports alone,” Hannula added.
The study will be published in Psychological Science, a journal by the Association for Psychological Science.