Retrieving information from declarative memory requires conscious intention and mental effort.
Examples of declarative memory include memorizing classification systems, people’s birthdays, or phone numbers.
Types of Declarative Memory
Declarative memory can be broken down into two types: episodic and semantic memories.
- Semantic memory: Facts are stored in semantic memory.
- Episodic memory: Information about experiences is stored in episodic memory.
Historically speaking, Endel Tulving (1972; 1983) has been one of the most influential researchers in the area of memory.
Regarding the distinction between semantic and episodic memory, Tulving (1983) made several noteworthy remarks:
“one system can operate independently of the other,” and most likely are “governed at least partially by different principles” (p. 66), although both systems are “closely interdependent and interact with one another virtually all the time” (p. 65).
Declarative Memory Examples
- Knowing the birthdates of your parents ─ Semantic
- Remembering what you and the love of your life said to each other the first time you met ─ Episodic
- Being able to remember the parts of the brain involved in reading comprehension ─ Semantic
- Quoting what a professor said during a lecture ─ Episodic
- Recalling the ingredients of a recipe ─ Semantic
- Describing the thoughts and feelings you had the first time you tasted an exotic dish in a foreign country ─ Episodic
- Listing the key historical events that led to the Civil Rights Movement ─ Semantic
- Remembering what it felt like the first time riding a roller coaster ─ Episodic
- Memorizing the periodic table ─ Semantic
- Recalling when and where you were when being told about a tragic event ─ Episodic
Common Properties of Declarative Memory
Tulving and Markowitsch (1998) provide a thorough description of the two types of declarative memory: semantic and episodic memory. They identify a list of common features of both systems.
Some of those common properties include:
- both semantic and episodic systems are large and highly structured
- both have unlimited capacity
- both have similar encoding processes (i.e., putting information into the system)
- information may or may not “match” the information in the real world
- encoding, storing, and retrieving information is influenced by context
- information in both systems is cognitive and can be contemplated and thought about
- information from either system can be expressed behaviorally
- both systems interact with other brain/behavior systems such as language, emotion, and reasoning
Although often considered to be independent systems, there is substantial overlap in characteristics and the two systems coordinate on many types of tasks.
1. Memorizing Classification Systems
The classification of all living organisms is how scientists group animals, plants, and fungi based on commonly shared characteristics. The process involves identifying the common characteristics of a group, naming each organism within it, and organizing the different groups.
When students study the classification system for animals, they have to commit to memory the distinguishing characteristics of different species.
The system utilizes Taxonomic Ranks, which categorizes species into increasingly smaller groups. As the groups become smaller, the members become more similar.
There are 8 taxonomic ranks. Remembering each one can be facilitated by using the mnemonic: “daring king Phillip came over for good spaghetti.”
The names of the different animals, the characteristics, and their taxonomic placement are all facts that are stored in declarative memory.
2. False Episodic Memory
Episodic memory is not always accurate. Although it “feels” accurate because we can almost see our experience unfold in our mind, as it turns out, it can contain a lot of errors. Those errors are called “false memories.” Now, normally, not remembering something that happened in the past with 100% accuracy is no big deal. Until it’s not.
Take the case of eyewitness testimony, when a person has observed a crime and then needs to testify in court as to what happened and who did what.
Research by psychologist Elizabeth Loftus (1997) demonstrates that the memory of an eyewitness can be easily influenced by just a single word.
As she explains: “False memories are constructed by combining actual memories with the content of suggestions received from others” (1997, p. 75).
3. Writing an Essay (Semantic Memory)
Writing an essay for an exam prompt should involve a lot of information retrieval. If the student has studied well and committed the relevant facts to memory, then that information will be easily utilized when the student responds to the exam question.
First, the student will need to search for the pertinent information in their long-term semantic storage system.
If the facts and concepts are located in long-term storage, then they need to be retrieved and processed in working memory. The final step is to organize the information into a coherent essay and transmitted on paper.
All of this of course depends on if the student engaged in sufficient studying to commit those facts and concepts to memory.
The other crucial step is transmitting the information in the form of the written word. Knowing is one thing, being able to create a clearly written response is quite the other.
4. Mood-Congruent Memory (Episodic Memory)
People have a tendency to remember negative events when in a bad mood, and positive events when in a good mood. This is referred to as mood-congruent memory (MCM).
MCM has been identified by clinical psychologists as an especially strong habit of people suffering from depression (Faul & LaBar, 2022).
For example, the day after delivering a speech, a depressed person will often dwell on aspects of the speech that did not go exceptionally well. They might ruminate on those moments for days, even weeks.
It is this kind of negative recall bias that only exacerbates depression. When in therapy, a clinician may call attention to this habit and present strategies to change the patient’s outlook, encouraging them to focus on aspects of the speech that went well.
There are significant differences between mood-congruent, state-dependent, and context-dependent memory. It is easy to get them confused.
Declarative memory consists of semantic and episodic information. There is substantial overlap in their characteristics and properties, even though they store completely different types of information.
Both systems are involved in the performance of a wide range of tasks. When trying to recall facts and concepts while writing an essay, we are retrieving information from semantic memory. Hopefully it is there to be retrieved.
At the same time, we may attempt to access our episodic memory and recall what the professor said in relation to those same facts and concepts.
This illustrates the independence and interconnectedness of the two systems.
Research has revealed that false memories are easily created, which has ramifications throughout the legal system. Other studies have revealed that we are more likely to remember mood-congruent information, which may play a role in depression.
Faul, L. & LaBar, K. (2022). Mood-congruent memory revisited. Psychological Review. https://doi.org/10.1037/rev0000394
Loftus, E. F., & Palmer, J. C. (1974). Reconstruction of automobile destruction: An example of the interaction between language and memory. Journal of Verbal Learning and Verbal Behavior, 13(5), 585–589.
Loftus, E. F. (1997). Creating false memories. Scientific American, 277(3), 70-75.
Riedel, W. J., & Blokland, A. (2015). Declarative memory. Cognitive Enhancement, 215-236.
Renoult, L., & Rugg, M. D. (2020). An historical perspective on Endel Tulving’s episodic-semantic distinction. Neuropsychologia, 139, 107366. https://doi.org/10.1016/j.neuropsychologia.2020.107366
Tulving, E. (1972). Episodic and semantic memory. In E. Tulving & W. Donaldson (Eds.), Organization of Memory, (pp. 381–403). New York: Academic Press.
Tulving, E. (1983). Elements of episodic memory. New York: Oxford University Press.
Tulving, E., & Markowitsch, H. J. (1998). Episodic and declarative memory: role of the hippocampus. Hippocampus, 8(3), 198–204. https://doi.org/10.1002/(SICI)1098-1063(1998)8:3<198::AID-HIPO2>3.0.CO;2-G