The neural correlates of different sources of surprise: Evidence from two naturalistic fMRI studies

COEX 

In general, we experience surprise when an observation contradicts expectations based on our past experiences. However, we can be surprised for different reasons, depending on the source of our expectations. Expectations can be flexibly drawn from either our general knowledge about how the world works or memories of specific episodes in the past. Because current leading theories on how surprising events are processed do not account for this complexity in sources of predictions, it is unclear if surprise based on different sources of expectations engage the same or distinct neural processes. A currently prominent view is that the hippocampus acts as a comparator between prior experience and incoming information, and plays an important role in detecting events that mismatch our expectations (e.g. Kumaran & Maguire, 2007; Barron, Auksztulewicz, Friston, 2020). However, this idea stems from work in which participants learned arbitrary associations which were violated after minimal delay. For example, violating the temporal order or spatial arrangement of recently experienced items (e.g. Kumaran & Maguire, 2006; Duncan et al., 2012). In short, these studies have demonstrated a role of the hippocampus in processing surprise based on episodic-like memories. However, outside of the laboratory we often rely on our general semantic or schematic knowledge to predict what is likely to happen in a given situation (Elman & McRae, 2019). While some theories predict increased hippocampal engagement when there is a mismatch between prior schematic knowledge and current experience (e.g. SLIMM framework, van Kesteren et al., 2012), there is no direct evidence to support this idea.