Cognitive mechanisms underlying memory-based choices

Most decisions we encounter in our daily life rely on past experiences. Before choosing where to go for dinner, we may think where we got delicious food last time. Suddenly, a restaurant comes to our mind that served only mediocre food. Then, instead of searching for other possibilities, we decide to go there again. We define this effect as memory bias: The tendency to prefer better-remembered options even if their value is below average. The aim of the present thesis is twofold. It first aims towards a better understanding of the neural mechanisms underlying memory-based choice (Manuscript 1) by reviewing the current findings of the relationship between a classical memory region (Hippocampus; HPC) and a classical valuation region (ventromedial Prefrontal Cortex; vmPFC). Second, the thesis focuses on two possible mediators explaining the influence of episodic memory on choice. The first mediator is uncertainty(Manuscript 2). Our hypothesis is that options that are remembered less are also more uncertain. As humans have a general tendency to avoid uncertain things, people prefer the better-remembered option. The second mediator is attention (Manuscript 3). We claim that visual attention mediates the memory bias as better-remembered items receive more attention and are thus chosen more often. The review article in Manuscript 1 shows that the HPC and the vmPFC are communicating with each other during memory-based decisions. Several theoretical models try to explain this connectivity. The classical view states that HPC serves as a memory-encoding and retrieving instance while the vmPFC orchestrates what needs to be recalled for a specific choice as a central executive. Other views move away from this classical role differentiation to a common integration: both regions are involved for example in future thinking, and therefore both are relevant for memory-based decisions. Manuscript 2 shows that people have a memory bias with appetitive stimuli (monetary gains or positive images), but the effect reverses with aversive stimuli (monetary losses or negative images). This is analogous to the reflection effect in decisions under uncertainty. Manuscript 3 shows that even though people do not pay more attention to better-remembered options, what they look at and for how long influences choices to a larger degree when they require memory retrieval during choice. In sum, this thesis sheds light on the mechanisms underlying memory-based choice combining different techniques such as eye-tracking or computational modeling. Further directions are investigating the role of HPC in memory-based choice or the development of the memory bias over the life span.