2025 Theses Doctoral

The paradox of prior knowledge: How both predictability and novelty benefit episodic memory

Gasser, Camille Claire

We make sense of the present by comparing it to the past. Our capacity for memory makes this comparison possible, characterizing each experience by how much it conforms to or diverges from what we already know. Some events — like commuting to work or cooking your favorite meal — follow a predictable and well-defined structure, whereas others contradict or elude expectations.

In this dissertation, I present a series of experiments that explore how the two ends of this continuum, predictability and novelty, affect how we learn from and remember our experiences.

Chapter 1 begins by demonstrating that the execution of a predictable and well-learned sequence of actions during learning scaffolds memory for the temporal structure of concurrent events.

In Chapter 2, I use functional magnetic resonance imaging (fMRI) to explore the neural basis of this “scaffolding” effect. I find that the brain maintains representations of predictable sequence knowledge during encoding, and that the strength of these representations helps to stabilize activity in the hippocampus and visual cortices and to promote temporal order memory.

Finally, Chapter 3 turns to focus on how novelty embedded in our day-to-day lives impacts memory for real-world autobiographical events. Using an intensive longitudinal “daily diary” design, this last study reveals that engaging in new or atypical experiences bolsters memory not only for the novel events in question, but also for non-novel events that occur nearby in time. Taken together, these findings shed light on how episodic memory can benefit from both novelty and familiar structure, illustrating how what we remember is shaped by the expectations we carry with us.