The Role of Memory Reactivation Strength in the Recall of Negative Memories

Abstract

People vary widely in their ability to cope with negative memories, which raises the question: How do people regulate negative emotional memories, and why are some people better at dealing with negative memories than others? This thesis investigates these questions through the basic science lens of cognitive neuroscience, specifically looking at how memory reactivation strength can predict one’s ability to deal with negative memories. In the first study, I used functional magnetic resonance imaging (fMRI) to investigate the relationship between memory reactivation strength during a memory suppression task (where participants had to intentionally not think of a target image during no-think trials) and memory performance. Although I was able to behaviorally demonstrate memory suppression, or the stopping of unwanted memories from coming to mind, I was un- able to show a relationship between memory reactivation strength, measured using fMRI, and memory suppression. In the second study, I sought to obtain eye tracking evidence for the reinstatement of emotionally negative and neutral stimuli that was related to behavioral memory performance. I was indeed able to link eye movements with memory performance. During a background recognition task, I found evidence of gaze reinstatement, especially for trials for which the backgrounds or objects were correctly recognized. Furthermore, memory for item identity was more tightly linked to gaze reinstatement of the item location when the stimuli were negative as opposed to neutral, although this last result was not stable across experiments. Finally, in the third study, I characterized the eye movement patterns that lead to memory suppression, specifically looking at how the strength of gaze reinstatement impacts subsequent memory performance. Critically, I identified eye movement patterns that differentiated no-think trials from think trials (when participants have to bring a target image to mind), as well as patterns that differentiated no-think trials that led to successful versus unsuccessful memory suppression. Taken altogether, my dissertation explores the role of memory reactivation strength in the recall (and suppression) of negative memories. These findings have the potential to elucidate ways in which memory reactivation can be leveraged and optimized in strategies to cope with negative, unwanted memories.