PSY 100 – General Psychology
Lecture Guide 9: Memory
Michael L. Thomas, PhD
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1 Memory
Before we begin, try to remember this sentence: Joe broke a bottle during the bar room brawl.
Memory involves three fundamental processes:
- Encoding: Transferring physical input (e.g., sound waves) into some kind of code that your memory can store.
- Storage: Retaining or storing the physical representation of memory (i.e., the code) until it needs to be accessed again.
- Retrieval: Recovering that coded memory when needed.
Memory can go awry during any of these stages. Each stage depends on a different location of the brain. For example, the hippocampus is critical for encoding new memories, while the prefrontal cortex supports retrieval.
We can also distinguish between different types of memory:
- Sensory memory: Holds a large amount of sensory information for a very brief period of time (roughly 1/4 second to 3 seconds) and acts as a buffer for stimuli received through the senses.
- Short-term memory (STM): Holds a limited amount of information for about 15–30 seconds. This is the system we use to temporarily store information while we process it further (i.e., working memory).
- Long-term memory (LTM): Stores information over extended periods—potentially for a lifetime. Long-term memory has a virtually unlimited capacity, although retrieval can sometimes be effortful or incomplete.
2 Working Memory vs. Short-Term Memory
Working memory can be thought of as a general framework for integrating consciousness, sensory input, and long-term memory, while short-term memory refers to the temporary storage of information in the brain. For example, in the Baddeley (2000) model, working memory is conceptualized as an integrative process that binds sensory input and short-term stores for phonological and visual information with long-term representations, such as language and visual semantics.
Encoding in working memory often relies on phonological (sound-based) encoding rather than semantic (meaning-based) encoding. This can lead to confusion when trying to remember items that sound similar. For instance, a sequence like TBECGV is harder to recall than RLTKSJ because of overlapping phonological features. In general, people show a preference for phonological encoding over visual encoding in short-term memory tasks.
Storage capacity in working memory is surprisingly consistent: most people can hold about 7 ± 2 items—roughly the length of a standard telephone number. Information is retained temporarily through rehearsal, or the conscious repetition of items in mind.
Note: Cowan (2001) proposed that the true capacity of working memory is closer to 4 chunks of information, particularly when rehearsal and long-term memory strategies are minimized. Why then can we often maintain roughly 7 items? This is because we can chunk information together. For example, the digits 1 and 0 are likely to be remembered as “ten” rather than “one, zero.”
Because working memory operates within conscious awareness, retrieval is typically not a major challenge. Once attention shifts or interference occurs, unrehearsed information is likely to be lost.
3 Long-Term Memory
Long-term memory includes both explicit (declarative) memory—our conscious recall of facts and events—and implicit (nondeclarative) memory, which involves skills, habits, priming, and classical conditioning.
Research with amnestic patients offers compelling evidence that different types of memory rely on separate brain systems. For example, individuals with anterograde amnesia—who cannot form new long-term memories—may show no conscious recollection of having performed a task, yet still improve on that task with practice. For example, such patients can learn to trace shapes while looking in a mirror, a skill requiring visual-motor coordination. Although they have no memory of previously completing the task, their performance improves over time, demonstrating that procedural memory (a type of nondeclarative memory) can remain intact even when declarative memory (conscious recall) is impaired.
A similar pattern emerges in priming tasks. In word-stem completion tests, prior exposure to a word like “table” increases the likelihood that someone will complete “ele___” with “elephant” (vs. “elevate” etc.), even if they do not consciously recall seeing the word earlier. Amnestic patients often perform normally on these tasks, indicating that implicit memory can function independently of explicit memory systems. Together, these findings support a distinction between declarative and nondeclarative memory, with the hippocampus playing a central role in forming declarative memories, and structures like the striatum, cerebellum, and neocortex supporting nondeclarative memory functions such as skill learning and priming.
Unlike short-term memory, which relies more on phonemic (sound-based) encoding, long-term memory relies more on semantic (meaning-based) encoding. In other words, if I asked you who the first president of the United States was, you would likely recall the person George Washington—not just the sound of the name, but also associated knowledge such as his image, historical role, and significance—rather than simply retrieving the phonemes GE–OR–GE WA–SH–ING–TON. In fact, semantic encoding is generally the preferred method of encoding information into long-term memory—even for nonverbal material. However, we also use other forms of encoding, such as acoustic, visual, and even olfactory (smell) or gustatory (taste) codes, depending on the context and type of information. We also only tend to remember the gist rather than exact details For example, you may not distinguish between being told “John suddenly came down with an illness” versus “Illness came to John when he least expected it.” But you’ll likely remember that John became sick quickly.
Once a long-term memory is well-formed, it is unlikely to be completely forgotten, even if some specific details fade over time. The primary cause of normal long-term memory loss is interference—when new and often similar information makes it harder to retrieve older and less-rehearsed memories. However, memory loss can also result from brain changes associated with normal aging, brain injuries, neurodegenerative diseases, or even psychiatric treatments such as electroconvulsive therapy (ECT).
Watch this! Follow this to a TED video that further explores how memories are made and lost.
4 Emotion and Memory
We tend to rehearse emotional memories more often than non-emotional ones. This contributes to the phenomenon of flashbulb memories—very vivid and detailed recollections of emotionally charged events. For example, many people born before the late 1990s can describe in great detail where they were and what they were doing on September 11th, 2001.
However, while emotion can enhance memory for certain details, it can also distort or interfere with memory accuracy. Anxiety, in particular, has been well established as a hindrance to memory performance. Additionally, context plays a key role in retrieval. For instance, you may find it easier to remember your first kiss if you return to the location where it happened. Likewise, you may recall information from this lecture better when sitting in the same seat where you originally learned it.
Another theory that addresses memory suppression is Freud’s theory of repression. According to this theory, some memories are too painful to consciously confront, and are therefore pushed into the unconscious to protect the individual from emotional distress. However, the research methodology for studying repressed memories is extremely challenging, and most of the evidence remains anecdotal.
5 Constructive Memory
❓ Without looking back answer the following: What type of bottle did Joe break during the bar room brawl?
This is a trick question. The sentence you were asked to remember did not mention the type of bottle Joe break. But there’s a good chance you guessed that he broke a beer bottle. Why? Because memory is constructed—our brain fills in gaps based on inferences, assumptions, and prior knowledge. The mind is not completely passive in remembering information. We often think of memory as a perfect record—like a photograph or video—but a wealth of research shows that memories are prone to distortion and error.
A common form of memory distortion occurs when individuals draw conclusions based on leading context or language. Loftus and Palmer (1974), for example, tested whether the wording of a question alters memory. Specifically, after viewing a car-crash film, participants were randomly assigned to one of three groups: asked a speed question using either the verb “smashed” or “hit,” or asked no speed question (control). One week later, everyone answered, “Did you see broken glass?”—there was no glass in the film.
The verb in the original question changed later memory reports:
| Condition | Said “Yes” to Broken Glass |
|---|---|
| Smashed | 32% |
| Hit | 14% |
| Control (no speed question) | 12% |
The data support the idea that leading questions can reshape memory representations (the misinformation effect).
Constructive memory is influenced by by what are called schemas—mental frameworks that help organize knowledge. People attempt to fit new information into preexisting schemas. In a classic study by Brewer & Treyens (1981), participants were asked to wait in what they believed was a professor’s office. Later, they were asked to recall the items they saw in the room. Participants correctly remembered common office items (e.g., desk, chair), but many also falsely recalled items that fit their office schema—like a filing cabinet or books—even though those items were not actually present.
Schemas can be useful in aiding memory. For example, in most barroom brawls, beer bottles are frequently broken, and so inferring that Joe broke a beer bottle will often be correct. However, schemas can also create serious problems when they are inaccurate, overgeneralized, or applied harmfully.
A stereotype is a type of schema that involves oversimplified and overgeneralized inferences about the traits or attributes of a group of people. In the context of memory, stereotypes have been shown to produce false memories about individuals based on demographic factors such as age, gender, and race. We’ll return to this topic in a later lecture.
📝 Complete this memory test!
Accessibility note: If you use a screen reader, check the “Screen-reader mode” box in the demo below to advance the word list manually. A full description of the task is also available in the video below.
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6 Improving Memory
Having a good memory is an asset that can help people succeed socially, academically, and professionally. Moreover, memory impairment is associated with several neuropsychiatric and neurological disorders, and therefore is a treatment target. Because of this, there has been a proliferation of products and techniques that claim to improve memory. However, only some of these methods are supported by scientific evidence.
Below are several strategies that have been shown to reliably improve learning and memory:
Elaboration: Making meaningful connections between new information and existing knowledge. For example, instead of simply memorizing a term, you might explain it in your own words or link it to a personal experience.
Spaced Repetition: Studying material over increasingly longer intervals of time, rather than cramming. This technique leverages the psychological “spacing effect” to enhance long-term retention.
Mnemonics & Visualization: Using memory aids, such as acronyms or vivid mental images, to organize and recall information more easily. For example, using the acronym “HOMES” to remember the Great Lakes.
Active Recall (Self-Testing): Practicing retrieval by testing yourself, rather than passively reviewing material. This improves retention and strengthens memory traces.
Regular Sleep and Exercise: Adequate sleep supports memory consolidation, and physical exercise has been linked to improved brain function and cognitive performance.
By using these evidence-based techniques, learners can significantly enhance their ability to store and recall information over time.
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