Explicit memory (or declarative memory) is one of the two main types of long-term human memory, the other of which is implicit memory. Explicit memory is the conscious, intentional recollection of factual information, previous experiences, and concepts. This type of memory is dependent upon three processes: acquisition, consolidation, and retrieval.
Explicit memory can be divided into two categories: episodic memory, which stores specific personal experiences, and semantic memory, which stores factual information.Tulving E. 1972. Episodic and semantic memory. In Organization of Memory, ed. E Tulving, W Donaldson, pp. 381–403. New York: Academic Explicit memory requires gradual learning, with multiple presentations of a stimulus and response.
The type of knowledge that is stored in explicit memory is called declarative knowledge. Its counterpart, known as implicit memory, refers to memories acquired and used unconsciously, such as skills (e.g. knowing how to get dressed) or perceptions. Unlike explicit memory, implicit memory learns rapidly, even from a single stimulus, and it is influenced by other mental systems.
Sometimes a distinction is made between explicit memory and declarative memory. In such cases, explicit memory relates to any kind of conscious memory, and declarative memory relates to any kind of memory that can be described in words; however, if it is assumed that a memory cannot be described without being conscious and vice versa, then the two concepts are identical.
Types
Episodic memory
Episodic memory consists of the storage and recollection of observational information attached to specific life-events. These can be memories that happened to the subject directly or just memories of events that happened around them. Episodic memory is what people generally think of when they talk about memory. Episodic memory allows for recalling various contextual and situational details of one's previous experiences.
Some examples of episodic memory include the memory of entering a specific classroom for the first time, the memory of storing your carry-on baggage while boarding a plane, headed to a specific destination on a specific day and time, the memory of being notified that one is being terminated from one's job, or the memory of notifying a subordinate that they are being terminated from their job. The retrieval of these episodic memories can be thought of as the action of mentally reliving in detail the past events that they concern. Episodic memory is believed to be the system that provides the basic support for semantic memory.
Semantic memory
Semantic memory refers to general world knowledge (facts, ideas, meaning and concepts) that can be articulated and is independent of personal experience. This includes world knowledge, object knowledge, language knowledge, and conceptual priming. Semantic memory is distinct from episodic memory, which is the memory of experiences and specific events that occur during people's lives, from which they can recreate at any given point. For instance, semantic memory might contain information about what a cat is, whereas episodic memory might contain a specific memory of petting a particular cat. Humans can learn about new concepts by applying their knowledge learned from things in the past.
Other examples of semantic memory include types of food, capital cities of a geographic region, facts about people, dates, and the lexicon of flowers; a language, such as a one's vocabulary or a person's final vocabulary both exemplify semantic memory.
Hybrid types Autobiographical memory is a memory system consisting of episodes recollected from an individual's life, based on a combination of episodic (personal experiences and specific objects, people and events experienced at particular time and place) and semantic (general knowledge and facts about the world) memory.Williams, H. L., Conway, M. A., & Cohen, G. (2008). Autobiographical memory. In G. Cohen & M. A. Conway (Eds.), Memory in the Real World (3rd ed., pp. 21-90). Hove, UK: Psychology Press.
Spatial memory is the part of memory responsible for recording information about one's environment and its spatial orientation. For example, a person's spatial memory is required in order to navigate around a familiar city, just as a rat's spatial memory is needed to learn the location of food at the end of a maze. It is often argued that in both humans and animals, spatial memories are summarized as a cognitive map. Spatial memory has representations within working, short-term and long-term memory. Research indicates that there are specific areas of the brain associated with spatial memory. Many methods are used for measuring spatial memory in children, adults, and animals.
Examples +Long-Term MemorySubtypeDescriptionExample Declarative (explicit)Conscious memory of facts and eventsSemanticFactual informationThe capital of Germany is BerlinEpisodicSpecific personal experiencesYour 10th birthday Non-declarative (implicit) Modes of learning that are nonconscious - one learning to perform a sequence of actions that do not necessarily invoke knowledge PrimingAlso known as pattern completion, where one has the ability to complete a pattern they have once seen before. This priming differs from priming in Psychology. If you were given a picture of half of a letter from the alphabet and you recognized which letter it is, you would be able to complete the letter. Perceptual learningPerceptual ability to differentiate sensories through experience of stimuliDifferentiating between categories such as smells, colors, tastes Category learning"...the process of establishing a memory trace that improves the efficiency of assigning novel objects to contrasting groups"Movie genres, breeds of dogs, types of fruitsEmotional learning"...retention of classically conditioned emotional relationships that cannot be voluntarily recollected or reported"Being afraid of dogs yet you cannot explain whyProcedural learningThe formation of skills and habitsLearning how to ride a bike
The model of language Declarative and procedural memory fall into two categories of human language. Declarative memory system is used by the lexicon. Declarative memory stores all arbitrary, unique word-specific knowledge, including word meanings, word sounds, and abstract representations such as word category. In other words, declarative memory is where random bits and pieces of knowledge about language that are specific and unpredictable are stored. Declarative memory includes representations of simple words (e.g. cat), bound morphemes (morphemes that have to go together), irregular morphological forms, verb complements, and idioms (or non-compositional semantic units). Irregular morphological structures fall into the declarative system; the irregularities (such as went being the past form of go or idioms) are what we have to memorize.
Declarative memory supports a superposition associative memory, which allows for generalizations across representations. For example, the memorization of phonologically similar stem-irregular past tense pairs (e.g. spring-sprung, sing-sang) may allow for memory-based generalization to new irregularities, either from real words (bring-brought) or from novel ones (spring-sprung). This ability to generalize could underlie some degree of productivity within the memory system.
While declarative memory deals with irregularities of morphology, procedural memory uses regular phonology and regular morphology. Procedural memory system is used by grammar, where grammar is defined by the building of a rule governed structure. Language's ability to use grammar comes from procedural memory, making grammar like another procedure. It underlies the learning of new, and already learned, rule-based procedures that oversee the regularities of language, particularly those procedures related to combining items into complex structures that have precedence and hierarchical relations- precedence in the sense of left to right and hierarchical in the sense of top to bottom. Procedural memory builds rule-governed structure (merging or series) of forms and representations into complex structures such as:
Phonology Inflectional and derivational morphology Compositional semantics (the meaning of composition of words into complex structures) Syntax
Broca and Wernicke's Brain Region Broca's area is important to procedural memory, because, "Broca's area is involved in the expressive aspects of spoken and written language (production of sentences constrained by the rules of grammar and syntax)." Broca's area corresponds to parts of the inferior frontal gyrus, presumably Brodmann's area 44 and 45. Procedural memory is affected by Broca's aphasia. Agrammatism is apparent in Broca's aphasia patients, where a lack of fluency and omission of morphology and function words occur. While those with Broca's aphasia are still able to understand or comprehend speech, they have difficulty producing it. Speech production becomes more difficult when sentences are complex; for example, the passive voice is a grammatically complex structure that is harder for those with Broca's aphasia to comprehend. Wernicke's area is crucial for language development, focusing on the comprehension of speech, rather than speech production. Wernicke's aphasia affects declarative memory. Opposite of Broca's aphasia, paragrammatism is apparent, which causes normal or excessive fluency and use of inappropriate words (neologisms). Those with Wernicke's aphasia struggle to understand the meaning of words and may not recognize their mistakes in speech.
History The study of human memory stretches back over the last 2000 years. An early attempt to understand memory can be found in Aristotle's major treatise, On the Soul, in which he compares the human mind to a blank slate.Aristotle, On the Soul (De Anima), in Aristotle, Volume 4, Loeb Classical Library, William Heinemann, London, UK, 1936. He theorized that all humans are born free of any knowledge and are the sum of their experiences. It was only in the late 1800s, however, that a young German philosopher by the name of Herman Ebbinghaus developed the first scientific approach to studying memory.Ebbinghaus, H. (1885). Memory: A Contribution to Experimental Psychology. Teachers College, Columbia University While some of his findings have endured and remain relevant to this day (Learning Curve), his greatest contribution to the field of memory research was demonstrating that memory can be studied scientifically. In 1972, Endel Tulving proposed the distinction between episodic and semantic memory. This was quickly adopted and is now widely accepted. Following this, in 1985, Daniel Schacter proposed a more general distinction between explicit (declarative) and implicit (procedural) memory.
With the recent advances in neuroimaging technology, there have been a multitude of findings linking specific brain areas to declarative memory. Despite those advances in cognitive psychology, there is still much to be discovered in terms of the operating mechanisms of declarative memory. It is unclear whether declarative memory is mediated by a particular memory system, or if it is more accurately classified as a type of knowledge. Also it is unknown how or why declarative memory evolved in the first place.
Neuropsychology
Normal brain function
Hippocampus
Although many psychologists believe that the entire brain is involved with memory, the hippocampus, and surrounding structures appear to be most important in declarative memory specifically. The ability to retain and recall episodic memories is highly dependent on the hippocampus, whereas the formation of new declarative memories relies on both the hippocampus and the parahippocampus. Other studies have found that the parahippocampal cortices were related to superior recognition memory.