On September 11th, 2016 we learned about

Long-term memories are influenced by our interests, understanding and opportunity to sleep

If you can’t remember some part of this post tomorrow, it may be because you didn’t feel that motivated by it, or that you just didn’t sleep enough. Both factors have been found to make a difference in converting short-term experiences into long-term memories, with the combination of both sleep and interest offering the best results. While sleep has been known to be a critical component of long-term memory formation for some time, the fact that personal motivations about the information to be retained sheds interesting light on just how subjective our memories are.

A sense of need, plus naptime

To discover how motivation intertwined with sleep to create long-term memories, test subjects were given the task of learning a few words in Welsh. After being presented with 28 words, participants were tested immediately, plus twelve hours later, after some had had a chance to get at least six hours of sleep.

People who didn’t sleep did predictably poorly, but the factor of motivation seemed to play an important role in how well the well-slept test subjects did. These participants had all just moved to Wales from English-speaking countries, and were asked how much they valued learning Welsh as part of this process. Caring about learning the presented information seemed to boost retention in the long-term testing, indicating that we help shape the memories we keep.

Purposely malleable memories

This might seem odd, since we often like to think of our memories as being an at least somewhat objective record of our experiences. However, this isn’t necessarily what our long-term memories are really for. Possibly to create a more flexible, efficient system, our memories can retain specific details, but are better at bundling things together by concept. As such, they can be influenced after the fact by thinking more about those higher-level concepts, to the point of being modified and rewritten. In this way, false memories can be created, especially if they’re conceptually related to actual information. An example is when people think they remember the word “cold” being included in a list that actually read “snow, ice, winter, warm.”

This may seem horribly unreliable, but it makes sense from the perspective of memory being a tool to help us solve problems. Rather than recount every specific detail of a scenario, our brains are likely trying to pull together information that will help us solve a problem when we encounter it a second or third time. The goal doesn’t have to be perfect recollection, as long as we can gain some efficiency at dealing with situations we’ve learned about in the past. Practicing a skill is a great way to build an accurate record of how to solve a problem, since it will let you build a larger and therefore more complete set of experiences on which to reference for later attempts at a task. Just make sure to get some sleep afterwards to allow things to have a chance to stick.

Source: Sleep 'prioritises memories we care about' by Robert Thompson, BBC Science & Environment

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