What is the difference between implicit and explicit memory?

Explicit memory is memory you can consciously bring to mind and put into words, such as a fact or a past event. Implicit memory shows up in what you do rather than in what you recall: a skill, a habit or a quicker response to something you met before, without any feeling of remembering. Explicit memory is also called declarative memory; implicit memory is also called non-declarative memory.

What is implicit memory?

Implicit memory is the influence of past experience on behaviour without conscious recollection of that experience. Its main forms are procedural memory (skills and habits), priming (faster or easier processing of something you have encountered before) and simple conditioning (learned responses, such as feeling tense in a dentist's waiting room).

What is explicit memory?

Explicit, or declarative, memory is memory you retrieve on purpose and can describe: what you had for dinner yesterday, the capital of Japan, the meaning of a word. It has two parts, episodic memory for personal events and semantic memory for facts and knowledge.

What is procedural memory?

Procedural memory is the implicit memory for how to do things: riding a bike, typing, tying shoelaces, driving a familiar route. It builds up gradually with practice, is hard to put into words and is usually very durable. The patient H.M., who could not form new conscious memories, still improved at a mirror-drawing task over three days.

What are examples of implicit and explicit memory?

Implicit: touch-typing without looking at the keys, completing a word fragment with a word you saw earlier without realising it, or tensing up at the sound of a dentist's drill. Explicit: remembering your first day at school, knowing that water boils at 100 °C at sea level, or recalling a phone number on purpose.

Is implicit memory linked to IQ?

Much less than explicit memory. In a 1991 study, performance on an explicit problem-solving task correlated strongly with IQ while performance on an implicit grammar-learning task did not. A 2010 study of 16- and 17-year-olds found implicit sequence learning more weakly related to intelligence than explicit learning and unrelated to working memory, although it was linked to processing speed and verbal analogies.

Implicit vs Explicit Memory: Differences, Examples

Explicit memory is memory you can consciously recall and put into words, such as facts and past events; implicit memory shapes what you do without any feeling of remembering, as in skills, habits and priming. Remembering where you learned to ride a bike is explicit; the riding itself is implicit. Psychologists also call the two declarative and non-declarative memory, and together they make up long-term memory.

Implicit vs explicit memory at a glance

Awareness: explicit memory comes with the sense of remembering or knowing; implicit memory works without it.
Other names: explicit = declarative (“knowing that”); implicit = non-declarative, with its best-known part, procedural memory, often summed up as “knowing how”.
What it holds: explicit memory holds events (episodic) and facts (semantic); implicit memory holds skills and habits, priming and simple conditioned responses.
How it is learned: an explicit memory can form in a single exposure; many implicit skills build up gradually with practice.
How it is measured: explicit memory by asking people to recall or recognise; implicit memory by watching performance change, for example faster or more accurate responses.
Brain basis: explicit memory depends on the hippocampus and nearby medial temporal lobe; implicit forms rely on other systems, including the striatum (habits) and the cerebellum (some motor and conditioned learning).

Explicit memory itself splits in two; our page on episodic vs semantic memory covers that division, and our long-term memory guide shows the whole map.

The types of implicit memory

Procedural memory: skills and routines such as typing, swimming, playing a scale or driving a familiar route. You can do them fluently but would struggle to explain every movement.
Habit learning: gradually picking up which cues lead to which outcomes, often without being able to say what you have learned.
Priming: seeing a word or picture makes it easier to identify or produce later. If you read “garden” and are then asked to complete “gar___”, you are more likely to write “garden” than “garlic”, even if you do not remember seeing it.
Classical conditioning: a learned reaction to a signal, such as tensing at the sound of a dentist’s drill.

Larry Squire’s widely used map of memory systems groups these forms together as non-declarative memory because they share one feature: the learning is expressed in performance rather than retrieved as a conscious memory.

Procedural memory: the part people search for most

Procedural memory is implicit memory for how to do things. It is the reason you can tie a shoelace while thinking about something else, and the reason a skill that took months to learn can survive years without practice. Its key features are that it improves step by step with repetition, it is hard to put into words, and it is largely preserved in people who have lost the ability to form new explicit memories. A common confusion is worth clearing up: knowing the rules of chess is semantic (explicit) memory; the fast, pattern-driven sense of a good move that comes with years of play has a large procedural component.

How each kind of memory is tested

Explicit tests ask directly: free recall (“list the words you studied”), cued recall and recognition (“did you see this word before?”).
Implicit tests never mention the earlier episode. People complete word stems or fragments, identify briefly flashed or incomplete pictures, or repeat a motor task; memory shows up as a benefit for items they met before.
Skill tasks measure procedural learning over sessions: tracing a shape seen only in a mirror, or reacting to a repeating sequence of lights that gets faster without the person noticing the pattern.

The terms “implicit” and “explicit” memory became standard after a 1985 paper by Peter Graf and Daniel Schacter. They showed that, after studying unrelated word pairs, both students and amnesic patients completed word fragments more readily when a fragment was shown alongside its original partner, which pointed to implicit memory for new associations that did not depend on conscious recollection.

The evidence that they are separate systems

H.M.’s mirror drawing. After surgery removed much of his medial temporal lobes, the patient H.M. could not form new conscious memories. Yet when Brenda Milner asked him to trace a star seen only in a mirror, he acquired the skill over ten trials and kept it across three days. Larry Squire describes this as the first hint that there was more than one kind of memory in the brain. His story is told in full on our long-term memory page.
A double dissociation. In a 1996 study, amnesic patients learned a probabilistic cue-outcome task normally but could barely remember the training session, while people with Parkinson’s disease, which damages the striatum, remembered the session but failed to learn the task. Each group kept the system the other had lost.
Priming without recollection. In Graf and Schacter’s experiments described above, amnesic patients showed the same word-completion priming for new associations as students did, despite their severe difficulty recalling what they had studied.

Most researchers now see these systems as distinct but cooperating. Learning a sport, for instance, starts with explicit instructions you hold in mind and gradually becomes procedural as the movements automate.

How long implicit memories last

Sometimes for decades. In a study published in 2006, David Mitchell mailed a picture-identification test to people who had seen a set of pictures for one to three seconds in his laboratory 17 years earlier. They identified fragments of the pictures they had seen better than fragments of new ones, and the advantage appeared even in people who said they had no recollection of ever taking part. A control group that had never seen the pictures showed no such difference.

Do implicit and explicit memory age differently?

Partly, and less neatly than many summaries claim. A common line is that implicit memory is stable across adulthood. A 1994 meta-analysis by Deborah La Voie and Leah Light, pooling 39 comparisons of younger and older adults, found that older people do show a smaller priming effect (a weighted effect size of 0.30), so the hypothesis of no age difference was rejected. But the age gap on priming was smaller than the gap on recall and recognition in the same experiments. The fair summary is that implicit memory holds up better with age than explicit memory, not that it is untouched.

Implicit memory, explicit memory and IQ

IQ tests mostly draw on explicit processes: holding information in working memory, reasoning about it and using stored knowledge. Research on individual differences fits that picture. In a 1991 study, Arthur Reber and colleagues found that performance on an explicit problem-solving task correlated strongly with IQ while performance on an implicit artificial-grammar task did not, and people differed much less from one another on the implicit task. A 2010 study of English 16- and 17-year-olds led by Scott Barry Kaufman found implicit sequence learning more weakly related to intelligence than explicit learning and unrelated to working memory, though it was linked to two components of intelligence (verbal analogical reasoning and processing speed), to results in French and German language exams, and to openness to experience. Implicit learning may be a modest ability in its own right, but it is not what an IQ score mainly captures; our guide to fluid and crystallized intelligence explains what is.

Trust and scope notes

This page summarises published research for general information, with figures taken from the studies listed below. It is not medical advice: memory problems that are new, worsening or worrying deserve a conversation with a doctor, and no online test can assess them. The IQ Revealed test is an online reasoning test of 40 original items for adults aged 18 and over; it is not a clinical assessment and it does not measure memory. Our guide to how IQ tests work explains what an online test can and cannot tell you.

IQ Revealed is not affiliated with, endorsed by or connected to the researchers, universities, journals or publishers named on this page. Names are used only to identify the research being described.

Implicit vs Explicit Memory: Differences, Examples and Procedural Memory