What is Memory?

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.

The Three Processes of Memory

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.

Types of Encoding

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:

Short-term memory (STM) primarily uses acoustic encoding — participants made more errors with acoustically similar words in STM tasks.
Long-term memory (LTM) primarily uses semantic encoding — participants made more errors with semantically similar words in LTM tasks.

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 of Memory

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 of Memory

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.

Why Memory Matters in Psychology

Memory is central to almost every area of psychology:

Cognitive psychology studies how memory processes work and how they can fail
Forensic psychology examines the reliability of eyewitness testimony and how memory can be distorted
Developmental psychology investigates how memory changes across the lifespan
Clinical psychology explores memory problems in conditions such as amnesia, Alzheimer's disease, and PTSD

Understanding memory is therefore foundational to the entire GCSE Psychology course.

Key Points

Memory involves three processes: encoding, storage, and retrieval.
STM primarily uses acoustic encoding; LTM uses semantic encoding (Baddeley, 1966).
STM has a duration of about 18–30 seconds without rehearsal (Peterson and Peterson, 1959).
STM has a capacity of approximately 7 ± 2 items (Miller, 1956).
LTM has potentially unlimited capacity and duration.
Chunking can increase the effective capacity of STM.