Memory Basics: Encoding, Storage, and Retrieval

Storage and Consolidation

Storage refers to the process of consolidating a memory, which takes place in waves over at least 24 hours following an experience. Consolidation requires structural changes at the cellular level, making synapses more efficient and gene expression changes to produce proteins that help maintain the physical changes supporting a memory. For as long as the next ten years and possibly even more, the brain works to integrate the new memory into existing networks. Where does it fit? How is it connected to what I already know? 

As far as we know, human memory storage is unlimited, but the consolidation process takes time. Limited amounts of data can be stored within a particular amount of time, which is one of the reasons cramming is not an effective strategy. 

A significant body of research shows that learning many types spaced out over time is vastly superior to learning that takes place in a brief period. We all appreciate the fact that elite athletes and musicians practice nearly every day, but somehow, we might mistakenly think that the brain works differently when it is practicing for a final exam. It does not. Cramming the night before a test makes no more sense than elite athletes’ cramming all of their practice into the night before a championship competition.

Stages of Memory

Information flows through the memory system and often drops out along the way. As students, we aim to move the information we need into long-term memory. How do we get there?

The first stage of information processing takes place in sensory memory. Huge quantities of incoming information, all the sounds, sights, tastes, smells, touches happening right now, are held for fractions of a second to a second or two. This is long enough to make a decision about what merits further processing and what does not. Any information that doesn’t make the grade here will not be available later. We all lived for 24 whole hours yesterday—how much of that do you really remember?

Information that seems important moves next to short-term memory. Short-term memory works like a piece of scratch paper that you can scribble something on and then discard. It has a very small capacity and lasts a very short period of time. 

Incoming data are constantly pushing out older bits. Some of the information in short-term memory is used immediately, so you don’t worry about losing it when it fades. You might repeat a new friend’s phone number to yourself as you retrieve your phone, but once you safely input the number, you probably just forget it. But short-term memory also serves as the gateway to more permanent storage. Without further work, you might lose the information you need.

The final memory stage is long-term memory, which has none of the space and duration limitations of the other two. Very elderly people can still remember childhood experiences vividly, and yes, indeed, you can teach an old dog new tricks. In fact, the more you know about a topic, the easier it is to learn something new about it, because you have a pre-existing structure for thinking about that topic. This is one of the reasons that students often find their tougher major courses to be easier than their general education courses.

Exploring Study Strategies: Distributed Practice, Inteleaving, Chunking, Elaboration & Recitation

Now that you have a better idea of how memory works, it’s time to consider ways to take advantage of this knowledge. Cognitive scientists have not only gained a fairly clear picture of information processing but have also shared practical, evidence-based strategies for learning more efficiently.

We already mentioned one important strategy—don’t cram. The opposite of cramming is distributed practice. Approach your studies like an Olympic athlete—do something every day, even if it’s just for a few minutes. Over the course of a term in school, those minutes add up. Not only is this a great memory strategy, but most people find it reduces stress. Nobody likes the feeling of being behind in their studies. You’ll sleep well knowing “I did something toward my organic chemistry work today,” even if what you did was relatively minor.

One question that I always had in my student days, which has now been answered by cognitive science, is whether it is better to concentrate on one subject at a time or to mix it up a bit more. The latter, called interleaving, shows superior results in memory experiments. Looking at your study plans for the day, see if you can divide the time you’ve set aside to do a little bit on each subject instead of having a “math night” or a “chemistry night.” This might not always be feasible, such as when you have a major exam or project due soon, but in general, mix it up whenever possible.

As mentioned previously, short-term memory is the gateway to more permanent storage, but its limited capacity often gets in the way. One way to expand short-term memory capacity is to take advantage of chunking. Group similar concepts in your mind as you hear them. Make categories. We often do this spontaneously, such as grouping the last four digits of a phone number as fifteen twenty-two instead of trying to remember 1-5-2-2. Consciously applying this strategy when appropriate can free up some precious short-term memory space for other things.

Unfortunately, students often view their job as regurgitating facts presented by a teacher. Not only is this poor educational practice, but it isn’t great for your memory. If your education is to have a lasting, meaningful result, and you are paying quite a lot for it, you are best off elaborating or thinking about why and how each bit of information is important. Elaboration means that you make the information personally relevant. A good instructor will help you do that through the use of examples, but each student comes to class with a very individual set of needs and experiences. Making the material personally relevant is one of the most effective memory strategies we know. Ask yourself how the information fits with what you already know. What can you do now that you know this information? What else should you know about this topic? 

My go-to method of studying in college was simple repetition. As mentioned previously, some of this is always necessary, but it’s not a perfect method. One of my discoveries in my first years of teaching was that talking about a topic in class made it easier to remember. At this point in my career, I rarely use any notes at all. If I see “amygdala” on my slide, I know what I want to say about it because I’ve talked about the topic so many times. 

We can harness this recitation effect on memory to make your study more efficient, something I would have loved to do as I juggled full-time work and college. Instead of rereading text and notes, get to a point where you think your understanding is good, but not perfect, and then try talking about it. Using flashcards or a list of key terms or text headings as prompts can get you started. Talk to your mom; talk to your classmates; talk to the mirror, if necessary, but talk!

Finally, the bottom line is that students usually worry about memory because they’re preparing for tests. And cognitive science shows that the best way to prepare for a test is to take tests! As part of your study strategy, take advantage of any practice tests your professor or textbook publisher provides. Write your own tests. Look online for tests on the same topics. If you had to take assessments like the ACT or SAT, you might have found the practice tests to be helpful, and this principle holds for other types of tests as well. 

These last two strategies, recitation and taking practice tests, have a significant additional advantage. They tell you very quickly what you don’t know! I have lost track of the times I believed I understood something very well, such as a new research finding in my morning news, only to stumble over it unpleasantly when I try to explain it to my classes. 

Metacognition refers to the executive process that helps you figure out what you do and do not know. Our metacognition can overestimate what we know, especially when we are not familiar with a topic. Using the recitation and practice tests approaches are some of the best ways to avoid overconfidence in your knowledge.