You have 3 main long term memories:

  1. Procedural memory: your memory of how to do things (text, talk, sing, dance, ride a bike, drive, etc.), primarily learned by practicing those skills. When people talk about "muscle memory," they are often referring to procedural memories for a motor skill. However, procedural memories are not limited to motor skills. A writing, speaking, pottery-making, musical performance, acting, critical thinking, or other "skills" class may try to add to your procedural memory--as might a senior-level capstone course, internship, or practicum.
  2. Semantic memory: your dictionary/encyclopedia of impersonal, factual knowledge (e.g., knowing what an elephant is or what short-term memory is). Most of your content courses in college focus on adding concepts to your semantic memory. Trivia games like Jeopardy also test your semantic memory. (Experts are alarmed by American's poor semantic memory for history--only about 1/3 of American adults could pass the U.S. citizenship exam.)  If your semantic memory was working very poorly, it would greatly affect your perception of familiar things. Specifically, you would sense familiar objects, but you would not recognize what they were. You might be like the music professor who mistook his own reflection for that of an ape, mistook parking meters for children, mistook his foot for his shoe, and mistook his wife's head for a hat (you can learn more about his case by reading about "The Man Who Mistook His Wife for a Hat"). In some cases, a person suffering a stroke may also suffer semantic memory losses that make them unable to understand many words, which, of course, makes it hard for them to communicate with others
  3. Episodic (autobiographical) memory: your diary of events in your personal life (what you did last week, your life as a reality show with many episodes). In a sense, episodic memory allows you to travel back in time. Note that, unlike semantic memory, episodic memories are often tied to a place and a time--and recall may feel like a "re-run" of the original episode. For example, when you recall a semantic memory like that George Washington was the first president of the U.S., you don't  recall where and when you learned that fact (it is almost as if you have amnesia for when and where you were when you learned it). However, when you recall an episodic memory like the January 6, 2021 riot at the Capitol, you may recall details about where you were, what you were doing, and when it was that you heard that news. 

     Without your episodic long-term memory, you would live only in the present plus the few seconds that short term memory would buy you. (To you, your life would be an empty book.) To see how challenging that would be, consider the case of Clive Wearing, a man without the ability to form new episodic long term memories (note that his procedural memory is fine: he can sing, conduct, read, write, etc.). For a thrilling fictional example that demonstrates the importance of episodic memories and the difference between episodic and other memories, watch "The Bourne Identity" in which the Matt Damon character has lost all episodic memories (he doesn't know who he was), but his procedural and semantic memories are intact. If you want to look at cases of extremely good episodic memories, you can watch this 13-minute segment from "60 Minutes" about the approximately 56 people who have been identified as having fantastic episodic memories for almost every day in their lives (from adolescence to now) If you watch that video, consider 5 points:

  1. As would be expected from what episodic memory is, recall of these episodic memories often seems like reliving the past event. That is, these episodic memory wizards often seem to experience the same emotions and sensations they felt when they first experienced the event.
  2. As would be expected from episodic memory being different from semantic memory and from episodic memory being primarily an autobiographical memory, these episodic memory wizards do not have superior memory for things they do not directly experience. Because their semantic memories are not better than the average person, they would not necessarily get better grades in college than other people.
  3. Interestingly, memory wizards' superior episodic memory seems to be due primarily to slow forgetting--the average person's memory for yesterday's events rivals theirs. So, perhaps, with better retrieval strategies, we could all have impressive recall for our past experiences.
  4. The video implies that being able to say what day of the week corresponds to a certain date is a great memory feat. It could be, but a person could also figure out the day of the week from the date without having a great memory. In fact, you can learn to calculate the day of the week from the date using the instructions here. Are these memory wizards using a formula on the date to compute the day of the week and then using the day of the week as a cue for triggering their memories?
  5. Having a tremendous episodic memory can be a blessing (as the video suggests), but it can also be a curse.

* Terminology note #1: Since you can explicitly tell  (i.e., you can declare to ) others the contents of both your semantic memories (e.g., you can declare that George Washington was a president) and your episodic memories (e.g., you can declare that your high school graduation was held in the gym or on Zoom), semantic and episodic memory are often referred to as  types of  declarative memory (also called explicit memory). Since you cannot easily declare the contents of your procedural memories (e.g., you know how to ride a bike but can't tell others what you know that allows you to ride a bike), procedural memory is a type of  non-declarative memory. To make the distinction between declarative and procedural memories clear, psychologists often say that the difference between declarative and procedural memories is the difference between "knowing that" (e.g., knowing that George Washington was president [semantic memory] or knowing that your high school graduation was in the gym [episodic memory])  and "knowing how" (e.g., your ability to text, read, sing, or dribble a basketball). Because procedural memory is acquired through practice and is not verbal, those who can perform a skill often can't teach it. (For example, if you are learning a foreign language, a young child from that country might pronounce the language's sounds better than you do but be unable to tell you how to move your lips and tongue to pronounce those sounds.) Fortunately, you are not always completely on your own when it comes to learning a skill because a good teacher or coach can give you some pointers about what you should be doing. Actually doing it well, however, will still take extensive practice.

If visuals help you, mouse over this text to review STM and the two basic types of LTM: procedural and declarative.

* Terminology note #2: In addition to procedural memory, you have another non-declarative memory: implicit memory. Implicit memory involves, without trying, learning certain rhythms, sequences, or patterns through repeated experience: Your mind is automatically identifying patterns that allow you to know what will probably come next. The patterns that this "nexting" is based on can be simple (e.g., that thunder follows lightning) or can be complex (e.g., knowing grammatical rules such as knowing that when Yoda said "Ready are you?", he should have said "Are  you ready?"). Accurate intuitions, such as a fire chief sensing that a fire is not responding in a typical way, so he orders the squad to flee the building seconds before the building collapses; a wife knowing her husband's mood just from hearing him say "hello" when he answers the phone; or you knowing that a conversation is about to end, are due to implicit memory (for a review of the types of LTM, see this diagram).


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