Written by
Tony Ingram, PhD
Why do you remember how to ride a bike after years without practice, yet you struggle to recall your first few school teachers names?
One reason is that they are two different types of memory, and are therefore learned and forgotten differently.
It helps to understand types of memory when planning how to learn something — your approach to study and practice might differ significantly depending on the degree to which each type of memory is demanded. Study and practice techniques may have different effects for each (or even be applicable at all).
Short and simple, procedural memories refer to “knowing how“, while declarative memories refer to “knowing what“.
| Declarative | Procedural | |
|---|---|---|
| Memory Type | Knowing what | Knowing how |
| Example | What a hammer is. | How to use a hammer. |
| Brain Regions (see image below) | Medial Temporal Lobe, especially Hippocampus | Basal Ganglia, Cerebellum, Sensorimotor Cortex, etc. |
The distinction of these types of memory began to emerge through studies of patients who had suffered brain damage in various ways (e.g., Stroke), or through brain surgery. One famous case from the 1950’s was patient H.M. who after surgery to control epilepsy, was unable to form new declarative memories (such as remembering names or events) but was still able to improve on procedural skills, like drawing while looking in a mirror. Across days, he was able to perform the task better, but didn’t remember practicing! 1,2,3
Later research in both psychology and neuroscience strongly supported these findings. In the 1980’s, Larry Squire and colleagues clarified the distinctions by defining categories: “declarative” versus “non-declarative” and demonstrated that they are separate systems in the brain.4 These categorizations have largely stood the test of time across numerous studies and theoretical updates.5,6
Today, theories of learning, memory, and cognition typically include the procedural-declarative distinction. For instance, it features prominently in the ACT-R (Adaptive Control of Thought-Rational) theory,7,8 and continues to influence modern theoretical frameworks like the recently proposed 3R (Reasoning, Refinement, and Retrieval) framework of sensorimotor learning.9
Declarative and procedural memories are supported by distinct brain networks — but there is some overlap and interaction (as with all things in neuroscience).
Declarative memory primarily depends on structures in the medial temporal lobe, especially the hippocampus. This region helps form, store, and retrieve explicit memories about facts and events.10 For example, damage to the hippocampus often impairs a person’s ability to remember names, dates, or recent events — just as it did in the famous case of patient H.M.1,2,3
Procedural memory primarily involves a more diffuse brain network, including the basal ganglia, cerebellum, thalamus, and sensorimotor and parietal cortices (yes, that’s a lot of area).11,12 These areas are involved with the learning of new skills and habits. Studies show that individuals with damage to the hippocampus can still learn new skills as long as these regions are intact.
Although these systems appear to be largely separate, they do interact during complex real-world learning and performance. For instance, the declarative system supports learning instructions and strategies, while the procedural system supports learning the execution of those strategies as they gradually become more automatic.9 And even when skills have reached expert levels, one can still learn new strategies to control and manipulate these skills in new contexts.
Declarative memories include facts, concepts, or events that you can explicitly describe. Typically, they’re easy to verbalize: historical facts, your birth date, what you did last weekend.
Procedural memories, however, refer to skills and actions that you’ve learned and are difficult to verbalize. They include things like typing on a keyboard, riding a bike, or playing an instrument — things that you may be able to do incredibly well but describing how you’re doing it might be difficult.
| Declarative | Procedural |
|---|---|
| Historical facts, birthdays, phone numbers, math rules, famous places and names. | Typing on a keyboard, riding a bike, playing a musical instrument, math skills. |
Returning to our question at the beginning: “Why do you remember how to ride a bike after years without practice, yet you struggle to recall your first few school teachers names?” Procedural memories also tend to be more resistant to forgetting than declarative memories. “Like riding a bike” is something you might say about a procedural skill (that even though you haven’t done it in a while, you still can) while “use it or lose it” is something you might say about a declarative skill, like remembering facts from biology class.
Real world skills often require both types of memory. For example, learning to solve math problems might require both declarative knowledge of rules and procedural skills in calculation. Music involves procedural skills (moving the fingers to play the instrument) as well as declarative knowledge (musical notes and theory) — and the lines may feel like they blur when you start becoming an expert. Finally, consider cooking: which will involve a lot of knowledge about recipes, pairings, and so on, but dextrous skills in preparing (e.g., chopping and slicing), as well as an aspect of “taste” (as with the music example) that comes with experience yet is difficult to place in either declarative or procedural categories.
Either way, most complex skills can be broken down into pieces to make practice easier — and when you do that, understanding whether a skill is declarative or procedural in nature will help plan your learning journey.
Why does it matter to understand the difference between procedural and declarative memories?
Originally, it helped to explain strange symptoms of neurological patients, and neurosurgeons always appreciate understanding the risks associated with operating on certain parts of the brain. However, this information also helps all of us. When you’re learning anything, you’re building a memory. Knowing which type of memory you’re targeting can help you select the best methods for learning.
| Declarative | Procedural | |
|---|---|---|
| Spaced Practice |  | |
| Interleaving | | |
| Summarization | | Not really applicable |
| Action Observation | Not really applicable | |
For instance, if you’re preparing for a history exam (declarative), your approach should involve active recall strategies like retrieval practice — deliberately remembering material without looking at it, or testing yourself — because these techniques are best applied to strengthening declarative memories.13
If you’re learning a new sport or math skill (procedural), you should focus more on repeatedly practicing with many examples that slightly vary in the details or context — which helps you use the skill flexibly and in appropriate contexts.14 You don’t need to focus on retrieval, as every attempt of the skill achieves that — unless you attempt to describe the action from memory, which may offer some benefit, or use motor imagery (a topic we will write about soon), but the path to mastery is through regular, deliberate practice of the skill.15,16
Understanding these differences allows learners to tailor their approaches effectively, saving time and maximizing potential.
This section is optional — written for those of you who like to say “well, actually…” — because the majority of readers will want to understand just well enough to inform practical applications.
But if you think there’s a mistake, oversimplification, or oversight here, please do contact us, because yes, we will update this based on well reasoned arguments and research we’ve missed!
You may come across more complex classifications of memory elsewhere. For instance, a recent review by Camina and Güell in 2017 divided it up as such17:
And in that classification, Procedural is a sub-type of “non-declarative” and Declarative is synonymous with Explicit memory (which is not uncommon). On this website, we generally refer to procedural as including everything under non-declarative in Camina and Güell’s classification (I’ll explain why in a future article).
While the implicit / explicit distinction is an interesting one, it is perhaps not a great way to classify memories — a more recent theoretical framework for motor learning includes an excellent discussion on this topic.9 Implicit and explicit can mean different things in different contexts (e.g., statistical learning versus sports psychology). If we take explicit to refer to the reportability of the memory while implicit memories are not reportable (the classic example being how many people can ride a bike but cannot describe how), there are caveats. For instance, reportability can change over time — you may be able to describe what you’re doing as you’re learning, but once it becomes more automatic, the skill may become more difficult to describe. Finally, most real world skills contain some aspect of each.
At Pavlonic, we’re focused on understanding how to study, practice and train to learn and improve skills.
Memory classifications are not the scientific consensus textbooks would imply they are. Therefore, we take a practical approach to separating memory types. Declarative and Procedural are convenient in that they are:
For example, “retrieval practice” is one of the most effective methods for declarative learning — you purposefully try to recall the studied information without looking at it. However, it’s difficult to apply to procedural skills, unless you are simply going to recite the steps of some sequence or describe the skill — but instead, you should be simply performing the skill… and in a sense, every repetition of a procedural skill is an act of memory retrieval — making it unnecessary to intentionally implement “retrieval practice” for procedural skills.
Other types of memory are less interesting from a skill development perspective: for example, there should be no difference in applying retrieval practice to episodic vs. semantic memory, and skill development is largely about forming long-term memories, making many of the other categories less relevant. Applying a technique like interleaving practice to procedural skills should also be the same whether the memory type of interest is “associative” or “non-associative”. And whether you can even improve the size of your working memory is still debated in the literature.18
This isn’t to say none of these other categories are interesting — and we will do our best to point out caveats where possible, and acknowledge their importance when discussing how to master skills. But for the time being, the primary differentiation we will make on this website is between declarative and procedural skills.
