Our long-term memory is located in the back of the brain. It is made up of information that was once stored in our short-term memory (or working memory) which is located in prefrontal cortex in the front of our brain.
One of the reasons that long-term memory is important is because it is not just a warehouse of facts, but the seat of understanding. Our ability to think deeply, creatively and reflectively is largely dependent on schemas we have built up in our long-term memory over many years. Nicholas Carr explains about this process in his book The Shallows:
It was once assumed that long-term memory served merely as a big warehouse of facts, impressions, and events, that it “played little part in complex cognitive processes such as thinking and problem-solving.” But brain scientists have come to realize that long-term memory is actually the seat of understanding. It stores not just facts but complex concepts, or “schemas.” By organizing scattered bits of information into patterns of knowledge, schemas give depth and richness to our thinking. “Our intellectual prowess is derived largely from the schemas we have acquired over long periods of time,” says Sweller. “We are able to understand concepts in our areas of expertise because we have schemas associated with those concepts.”
Given the importance of long-term memory, we should do what we can not to overload our short-term memory (because, remember, the long-term memory grows out of the content in the short-term memory). Overloading our short-term memory will make it less likely that the relevant information—the information we want to remember—will find its way into our long term memory. Additionally, flooding our short-term memory with too much triviality and irrelevant stimuli, makes it harder for our long-term memory to develop the type of schemas and conceptual knowledge that come as a precondition to understanding. Again, Carr explains why this is:
The information flowing into our working memory at any given moment is called our ‘cognitive load.’ When the load exceeds our mind’s ability to store and process the information…we’re unable to retain the information or to draw connections with the information already stored in our long-term memory. We can’t translate the new information into schemas. Our ability to learn suffers, and our understanding remains shallow…. Experiments indicate that as we reach the limits of our working memory, it becomes harder to distinguish relevant information from irrelevant information, signal from noise. We become mindless consumers of data.
This should come as a challenge to those of us who take pride in our ability to multitask, to flip from one thing to another on the internet and supposedly maintain our concentration. The question is not whether we are good multitaskers. The question is the affect this activity is having on our brain. Remember, the ability to think deeply, creatively, reflectively and attentively depends largely on the understandings given us by our long-term memory. The long-term memory, in turn, is constantly being fed by information process in the short-term memory. However, such processing is atrophied by the type of cognitive overload experienced by the habitual multi-tasker.