Can the simple act of recognizing a face as you walk down the street change the way we think? Or can taking the time to notice something new on our way to work change what we remember about that walk? In a new study published in the journal Science, New York University researchers show that remembering something old or noticing something new can bias how you process subsequent information.
This novel finding suggests that our memory system can adaptively bias its processing towards forming new memories or retrieving old ones based on recent experiences. For example, when you walk into a restaurant or for the first time, your memory system can both encode the details of this new environment as well as allow you to remember a similar one where you recently dined with a friend. The results of this study suggest that what you did right before walking into the restaurant can determine which process is more likely to occur.
Previous scholarship has demonstrated that both encoding new memories and retrieving old ones depend on the same specific brain region–the hippocampus. However, computational models suggest that encoding and retrieval occur under incompatible network processes. In other words, how can the same part of the brain perform two tasks that are at odds with each other?
At the heart of this paradox is distinction between encoding, or forming a new memory, and memory retrieval, or recalling old information. Specifically, encoding is thought to rely on pattern separation, a process that makes overlapping, or similar, representations more distinct, whereas retrieval is thought to depend on pattern completion, a process that increases overlap by reactivating related memory traces.