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Memory is a fundamental cognitive process that allows us to encode, store, and retrieve information. Without memory, we could not learn from experience, form relationships, or carry out the most basic tasks. In psychology, memory is studied as a process rather than a single entity — it involves multiple stages, stores, and types.
Memory involves three key processes:
| Process | Description |
|---|---|
| Encoding | Converting information into a form that can be stored in memory. Information can be encoded visually (as images), acoustically (as sounds), or semantically (by meaning). |
| Storage | Holding information in memory over time. Different memory stores hold information for different durations and in different capacities. |
| Retrieval | Accessing and bringing stored information back into conscious awareness when it is needed. |
If any one of these processes fails, forgetting occurs. For example, information may never be properly encoded in the first place, it may decay from storage over time, or we may be unable to retrieve it even though it is still stored.
Research has shown that different memory stores use different types of encoding:
| Type of Encoding | Description | Example |
|---|---|---|
| Acoustic | Encoding information by how it sounds | Repeating a phone number aloud |
| Visual | Encoding information by how it looks | Remembering a face or a diagram |
| Semantic | Encoding information by its meaning | Understanding a concept rather than just memorising words |
Baddeley (1966) investigated the type of encoding used by short-term and long-term memory. He gave participants lists of words that were either acoustically similar (e.g. cat, cap, can) or semantically similar (e.g. big, large, huge). He found that:
Exam Tip: A common exam question asks you to explain the difference between encoding in STM and LTM. Remember: STM = acoustic, LTM = semantic (based on Baddeley's research).
Duration refers to how long information can be held in a memory store.
| Memory Store | Duration |
|---|---|
| Sensory register | Very brief — less than half a second for iconic (visual) memory, up to 3–4 seconds for echoic (auditory) memory |
| Short-term memory | Approximately 18–30 seconds without rehearsal |
| Long-term memory | Potentially unlimited — information can last a lifetime |
Peterson and Peterson (1959) investigated the duration of STM. Participants were given a trigram (a three-letter nonsense syllable, e.g. BVM) and asked to count backwards in threes from a given number to prevent rehearsal. After 3 seconds, 80% of trigrams were recalled correctly. After 18 seconds, only about 3% were recalled. This study demonstrated that STM has a very short duration (around 18–30 seconds) when rehearsal is prevented.
Capacity refers to how much information a memory store can hold.
| Memory Store | Capacity |
|---|---|
| Sensory register | Very large — all sensory experience is briefly held |
| Short-term memory | Limited — approximately 7 ± 2 items (Miller, 1956) |
| Long-term memory | Potentially unlimited |
George Miller (1956) published a famous paper called "The Magical Number Seven, Plus or Minus Two" which argued that the capacity of STM is approximately 7 items (give or take 2). He also identified a technique called chunking — grouping individual items into larger meaningful units to increase the effective capacity of STM. For example, the sequence 1-9-6-8-1-9-7-4 (8 digits) could be chunked into 1968-1974 (2 chunks), making it easier to hold in STM.
Memory is central to almost every area of psychology:
Understanding memory is therefore foundational to the entire GCSE Psychology course.