By Camillia Abidat and Léa Baroux
Everyone has a multitude of memories stored into their brain, ready to be remembered, shared, and pondered upon. For instance, a road trip with some friends or a family gathering. These memories are part of what is called the autobiographical memory. It allows us to develop ourselves, identity-wise, and it makes us who we are today.
Literature has shown that recalling a memory automatically triggers visual mental imagery of the event. In other words, when we think about a memory, a visual representation of the event can appear in our mind and make us feel like we are reliving the moment as it was first experienced. Moreover, studies suggest that specific eye movements are triggered by this recollection process: “saccadic movements”, described as fast eye movements, and “fixations”, characterized by a motionless state of the eyes. According to the literature, an autobiographical recollection will therefore trigger more saccadic movements and conversely, during a low demanding cognitive activity like counting one by one, more eye fixations are observed. Thus, studies concluded that the recalling of a memory triggers more mental visual exploration of the past scene, therefore more saccadic movements, than a control condition. Those studies were conducted on younger adults.
Yet, older adults are known to have autobiographical memory impairments. During a recollection, they evoke fewer details and more general elements of the event. They also have trouble forming and manipulating mental images. We also know that eye movements are impacted by the ageing process. However, as of now, no study has explored the effects of ageing on the links between autobiographical memory and ocular movements. The purpose of our final project is therefore to explore the effects of aging on the links between autobiographical memory and ocular movements. In other words, we will investigate whether the same ocular patterns are observed during recalling a memory between young and older adults.
For this purpose, we have created two conditions. In the control condition, participants were asked to count for two minutes straight and the “autobiographical condition” consisting of the out loud recollection of two events reminding them of the word “city”. Those two tasks were timed to last exactly two minutes and the participants were instructed to look at a white blank wall throughout the entire experiment. Under both conditions, the eye movements were recorded with an eye tracker monitoring the number and duration of fixations and saccadic movements.
The results of our experiment show that longer fixations are observed in the control condition than in the autobiographical condition. For older adults, they did a greater number of fixations than younger adults and have shorter fixations than younger adults in the autobiographical condition. The results also show that saccades are longer in the memory condition. For older adults, there is a greater number of saccades than for younger adults in the autobiographical condition and shorter saccades than for younger adults in both conditions.
Eventually, further studies of this topic may allow researchers and practitioners to find new ways to diagnose or treat older people with autobiographical memory-related conditions, such as Alzheimer’s disease and other (and related disorders). For instance, psychologists might be able to assess autobiographical memory by eye movements instead of the current ways. By monitoring eye movements while recalling an event, they would be able to detect episodic memory deficits in young and old people. Specifically with older adults, this method could be a way to detect episodic deficits at an early stage before language or memory disorders related to Alzheimer’s disease take hold.