Two kinds of memory and two kinds of retrieval

Two kinds of memory or knowledge

People talk about two kinds of learning or even two kinds of knowledge:

1. Conceptual knowledge: understanding definitions, concepts, rules, or principles
2. Procedural knowledge: being able to perform activities such as solving a math equation, applying the right grammar rule in the correct context

You can acquire conceptual knowledge by reading, listening to lectures and then thinking about it or even better discussing it with colleagues. With simple enough concepts, you can even learn something conceptually in a few minutes.

But procedural knowledge can only be acquired through practice and over time. It is relatively easy to learn a list of words and a few rules for using them. But when you try to actually say a sentence in a real context, that kind of knowledge seems completely out of reach. Your working memory simply is not big enough to retrieve the words, put endings on them and put them in the right order while also thinking about what you want to say or worrying about what the other person thinks of your accent.

The biggest mistake people make is to assume that just because they understand some concept, they can use it in actual performance. In general, people almost always practice too little and learn the rules too much. They value understanding over the ability to do something with that understanding.

And things get even worse. That is because conceptual knowledge actually relies on procedural knowledge. As the concepts get more complicated, it becomes more difficult to just keep all aspects of the ideas in your head. We learn concepts to do something with them. But if we can’t hold enough of the concept in our working memory at the same time as another one, even a simple thing like comparison is out of reach.

So it is worthwhile to insert little moments of practice even into conceptual learning. Particularly when encountering one of these:

• Abstract concepts
• Acronyms
• Terms, foreign words, names
• Equations
• Variables
• Functions

2. Is developed through engagement with content such as guides, lessons, etc. | 1. Developing fluency of performance in the area of competence
3. Relies on ability to perceive and act based on the perception
4. Is developed through a feedback loop of repetition and reflection |

Two kinds of retrieval: “Look and know” vs “Look up and know”

When we talk about conceptual or procedural knowledge, we always think of it as something that is stored somewhere in your brain or in our muscles (or a combination of both). But the actual question that is of interest to us here is how we retrieve those pieces of knowledge from this storage into working memory.

From this perspective we can differentiate between two types of memory retrieval based on the way we get its contents from wherever it is stored in a dormant state into our working memory where we can do something with it. They are:

1. Look and know
2. Look up and know

Look and know retrieval

Look and know retrieval of knowledge (or skill) is at the very foundation of our existence. As you go through the world, you look at things and you immediately know what they are. Objects, people’s faces, words you see or hear. When you need them, they just appear in your working memory for you to be able to think with them. They are almost integrated into your body. You want to pick up an object and you reach out and take it. You want to say a sentence about it and you just do it.

Look up and know retrieval

Look up and know is the kind of knowledge (or skill) retrieval that requires effort to make knowledge available for thinking with. It is like looking up a word in a dictionary before you say it. And that process takes time and mental energy which takes up a space in your working memory. You can do fewer things with knowledge that you have to look up before you can do something with it.

These two types are similar but not exactly the same as the conceptual vs procedural distinction.

Table comparing different types of knowledge and retrieval