Study links eye movements to real-time memory retrieval

The eyes may reveal how experiences are recalled according to new Baycrest research that suggests that shifts in eye movements play a critical role in memory retrieval. The findings offer new insight into how memory works and how it may change with brain disease.

The findings show that eye movements, specifically saccades, increase just before people recall episodic details - such as what was seen, heard or felt during past, real-life events - and decrease immediately afterward. This pattern was not observed when participants recalled non-episodic details, such as general facts or background information.

"By aligning eye movements with spoken recall on the order of milliseconds, we were able to see memory unfolding in real time," says Dr. Brian Levine, Senior Scientist at Baycrest's Rotman Research Institute and senior author of the study titled "Remembrance with gazes passed: Eye movements precede continuous recall of episodic details of real-life events," published online ahead of print in Cognition. "These findings show that eye movements are closely tied to the brain's processing and reconstruction of visual and spatial memories from past events, not just a byproduct of remembering."

In the study, 91 healthy young adults were asked to take an audio-guided museum-style tour of artworks and installations at Baycrest in Toronto, conducted in two ten-minute segments. One week later, participants freely recalled the tour while viewing a blank screen, as their eye movements were recorded using a video-based eye-tracking system. This approach allowed researchers to synchronize each eye movement with the precise timing of spoken narrative details.

The analysis revealed a striking pattern: episodic details were consistently preceded by a burst of eye movements and followed by a brief quieting of visual scanning before the next memory detail emerged. No such timing relationship was found for non-episodic content.

Main study findings:

• Eye movements increased approximately half a second before participants recalled episodic, event-specific details, but not when recalling general or non-episodic information.
• Eye movements decreased in the period immediately following these specific details.
• The eye movement patterns suggest that visual exploration plays a key role in reconstructing real-life experiences.

Autobiographical memory is often affected early in neurological conditions such as dementia. Understanding the fine-grained mechanisms that support memory retrieval could help researchers develop more sensitive tools for assessing brain health.

Natural, unconstrained behaviours like eye movements offer a promising window into cognitive function. Because they can be measured unobtrusively and repeatedly, they may eventually complement traditional memory assessments in both research and clinical settings."

Dr. Brian Levine, Senior Scientist at Baycrest's Rotman Research Institute and senior author of the study

The researchers note that similar principles may apply beyond dementia. Post-traumatic stress disorder (PTSD), for example, involves highly vivid and intrusive recollection of traumatic events, alongside functional and structural changes in visual brain networks. Effective interventions for PTSD aim to contextualize traumatic experiences and reduce the emotional impact of intrusive visual memories. Fine-grained behavioural analyses like those used in this study could help test and refine such interventions.

The team emphasizes that future longitudinal studies will be needed to determine how these eye-movement patterns change with normal aging and neurodegenerative disease, and whether they could serve as early markers of memory decline.

This research was led by Ryan Barker, a PhD student at Baycrest and the University of Toronto, and Dr. Jennifer Ryan, Senior Scientist at Baycrest's Rotman Research Institute.