How do psychologists model the structures and processes that allow us to encode, store and retrieve memories?
Describe the multi-store and working memory models of memory and explain the brain structures and processes involved in encoding, storage and retrieval
A focused answer to the QCE Psychology Unit 3 dot point on memory. Explains the Atkinson-Shiffrin multi-store model and Baddeley and Hitch's working memory model, the processes of encoding, storage and retrieval, and the brain structures (hippocampus, amygdala, cerebellum) shown by cases such as patient HM and studies including Peterson and Peterson.
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What this dot point is asking
QCAA wants you to explain how memory is structured and how information moves through it, using named models. You need to describe the multi-store model and the working memory model, distinguish the three core processes (encoding, storage, retrieval), and link memory functions to specific brain structures using named studies and cases.
The answer
The three processes
All memory models rest on three processes. Encoding is converting information into a usable form (acoustic, visual or semantic). Storage is retaining that information over time. Retrieval is recovering stored information when it is needed, either by recall (producing it) or recognition (identifying it). A failure can occur at any of these three stages.
The multi-store model (Atkinson and Shiffrin, 1968)
This model proposes three separate stores through which information flows in sequence.
- Sensory memory. Holds raw sensory input very briefly (iconic visual memory for under a second, echoic auditory memory for a few seconds). Sperling's (1960) partial-report experiment showed iconic memory has a large capacity that fades almost instantly.
- Short-term memory (STM). Limited capacity, around 7 plus or minus 2 items (Miller, 1956), and limited duration. Peterson and Peterson (1959) showed that without rehearsal, STM decays within about 18 seconds, because preventing rehearsal with a counting task caused recall to drop sharply.
- Long-term memory (LTM). Potentially unlimited capacity and duration. Information enters LTM through rehearsal and is divided into explicit (declarative) and implicit (procedural) memory.
The model's strength is its clear structure; its weakness is treating STM as a single passive store, which the working memory model corrects.
The working memory model (Baddeley and Hitch, 1974)
This model reconceives short-term memory as an active workspace with multiple components.
- Central executive. The attentional controller that directs resources and coordinates the subsystems.
- Phonological loop. Handles verbal and auditory information (an inner voice and inner ear).
- Visuospatial sketchpad. Handles visual and spatial information (an inner eye).
- Episodic buffer (added by Baddeley in 2000). Integrates information across the subsystems and links to long-term memory.
Evidence comes from dual-task studies: people can do a verbal task and a visual task at once with little interference, but two verbal tasks compete, showing separate subsystems.
Brain structures of memory
Memory is not stored in one place; different structures support different memory types.
- Hippocampus. Essential for forming new long-term explicit memories. The case of patient HM (Henry Molaison), who had his hippocampi removed to treat epilepsy, is the landmark evidence: he could no longer form new long-term memories (anterograde amnesia) but retained older memories and could learn new motor skills, showing the hippocampus is needed for forming, not storing, explicit memory.
- Amygdala. Attaches emotional significance to memories, which is why emotionally charged events are often vividly remembered.
- Cerebellum and basal ganglia. Support procedural (implicit) memory and motor skills, which is why HM could still learn the mirror-drawing task despite his amnesia.
Putting it together for an exam
A strong response names the model, describes its components, then links a process or store to a brain structure and a study. For example: forming a new long-term memory depends on the hippocampus, as shown by HM's anterograde amnesia after its removal. Connecting model, process, structure and evidence is what earns top marks.
Exam-style practice questions
Practice questions written in the style of QCAA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
2022 QCAA5 marksa) Identify the capacity and duration of short-term memory without the use of strategies. [2 marks] b) Describe chunking and discuss one argument for using chunking and one argument against using it to increase the capacity of short-term memory. [3 marks]
Show worked answer →
a) Capacity is about 7 plus or minus 2 items (Miller, 1956); duration is roughly 18 to 30 seconds without rehearsal (Peterson and Peterson, 1959). 1 mark each.
b) Chunking is grouping separate items into larger meaningful units, so a string of digits becomes a few chunks that each count as one item in short-term memory (1 mark).
For chunking (1 mark): it increases the effective amount held because capacity is measured in chunks, not individual items, so more raw information fits within the 7 plus or minus 2 limit.
Against chunking (1 mark): it relies on existing long-term knowledge to form meaningful chunks, so unfamiliar material cannot be chunked, and forming chunks takes effort and time that can disrupt rehearsal.
2023 QCAA2 marksDescribe two roles of the hippocampus in memory formation.Show worked answer →
Two distinct roles are required, 1 mark each.
The hippocampus encodes and forms new explicit (declarative) long-term memories, binding the elements of an experience into a single memory trace.
It consolidates these memories, gradually transferring them for long-term storage in the cortex.
Evidence: patient HM, whose hippocampi were removed, could no longer form new long-term memories (anterograde amnesia), confirming the hippocampus is needed to form, not permanently store, explicit memory.
2024 QCAA2 marksDescribe the role of the hippocampus in memory formation and storage.Show worked answer →
For 2 marks, address both formation and storage.
Formation (1 mark): the hippocampus is essential for encoding and forming new explicit long-term memories, integrating sensory and contextual details into a coherent memory.
Storage (1 mark): the hippocampus consolidates new memories and gradually transfers them to the cerebral cortex for permanent storage, so it is required to form and consolidate long-term memories rather than to store them indefinitely itself. Damage to the hippocampus (as in patient HM) prevents new long-term explicit memories from forming.