Memory: Models of Memory

What you'll learn

This guide covers the two main models of memory you need for Edexcel GCSE Psychology: the multi-store model and the working memory model. You'll understand how psychologists explain the structure and processes of human memory, including the different stores, their capacities, durations, and how information moves between them. You'll also learn key research evidence and be able to evaluate both models critically for exam success.

Key terms and definitions

Sensory register — The memory store that holds information from our senses (visual, auditory, tactile) for a very brief duration (milliseconds to seconds) before it's either attended to or lost.

Short-term memory (STM) — A temporary memory store with limited capacity (approximately 7±2 items) and duration (18-30 seconds without rehearsal), which holds information we're currently aware of or thinking about.

Long-term memory (LTM) — A permanent memory store with unlimited capacity and potentially lifelong duration, holding all our knowledge, experiences, and skills that aren't currently in conscious awareness.

Encoding — The process of converting information into a form that can be stored in memory (visual, acoustic, or semantic).

Retrieval — The process of accessing and bringing stored information from long-term memory back into conscious awareness.

Maintenance rehearsal — The process of repeating information over and over to keep it in short-term memory or transfer it to long-term memory.

Central executive — The component of working memory that directs attention, coordinates information from the slave systems, and controls cognitive tasks.

Phonological loop — The component of working memory that processes and temporarily stores acoustic and verbal information (sounds and words).

Core concepts

The multi-store model of memory

Atkinson and Shiffrin (1968) proposed the multi-store model, which describes memory as consisting of three separate stores that differ in capacity, duration, and encoding.

Structure of the model:

Information flows through the system in a linear sequence:

1. Environmental stimuli enter the sensory register
2. Information receiving attention passes to short-term memory
3. Information that is rehearsed transfers to long-term memory
4. Information can be retrieved from LTM back to STM when needed

Characteristics of each store:

The sensory register:

• Capacity: Very large (all sensory information)
• Duration: 250 milliseconds to 2 seconds
• Encoding: Modality-specific (iconic for visual, echoic for auditory)
• Information lost through decay if not attended to

Short-term memory:

• Capacity: 7±2 items (Miller, 1956)
• Duration: 18-30 seconds without rehearsal
• Encoding: Primarily acoustic (sound-based)
• Information lost through decay or displacement

Long-term memory:

• Capacity: Unlimited
• Duration: Potentially permanent (up to a lifetime)
• Encoding: Primarily semantic (meaning-based)
• Information may be lost through interference or retrieval failure

Key processes:

Attention determines which information moves from sensory register to STM. Without attention, sensory information decays rapidly.

Maintenance rehearsal keeps information in STM and helps transfer it to LTM. The more rehearsal, the stronger the memory trace in LTM.

Retrieval brings information from LTM back into STM for conscious use. This can fail, resulting in forgetting.

Supporting evidence:

The case of HM (Scoville & Milner, 1957) provides strong support. After brain surgery to treat epilepsy, HM could not form new long-term memories but his short-term memory remained intact. This suggests STM and LTM are separate stores located in different brain areas.

Glanzer and Cunitz (1966) demonstrated the serial position effect. Participants remembered words from the beginning of a list (primacy effect - transferred to LTM through rehearsal) and the end of the list (recency effect - still in STM) better than middle words. This supports the existence of separate memory stores.

Studies using brain scanning show different brain areas are active when using STM (prefrontal cortex) versus LTM (hippocampus), supporting the idea of separate stores.

Evaluation:

Strengths:

• Research support from brain-damaged patients like HM
• Explains primacy and recency effects in free recall
• Influential model that stimulated further research
• Simple and easy to understand

Weaknesses:

• Too simplistic - LTM isn't a single store (episodic, semantic, procedural memories exist)
• Rehearsal isn't the only way information reaches LTM (flashbulb memories form without rehearsal)
• Doesn't explain why we remember things we haven't rehearsed
• STM and LTM may not be completely separate (working memory model provides better explanation)

The working memory model

Baddeley and Hitch (1974) proposed the working memory model as an alternative explanation of short-term memory. Rather than a single STM store, they suggested an active system with multiple components.

Structure of the model:

The working memory model consists of four components:

Central executive:

• Controls attention and coordinates the slave systems
• Limited capacity
• Modality-free (can process any type of information)
• Most important component but least understood
• Directs information to appropriate slave systems

Phonological loop:

• Processes spoken and written material
• Limited capacity (what you can say in 2 seconds)
• Subdivided into:
  • Phonological store (inner ear) - holds words you hear
  • Articulatory process (inner voice) - rehearses words through subvocal repetition

Visuo-spatial sketchpad:

• Processes visual and spatial information
• Limited capacity (3-4 objects)
• Helps you plan spatial tasks
• Subdivided into:
  • Visual cache - stores visual information (colour, shape)
  • Inner scribe - stores spatial relationships and rehearses information

Episodic buffer:

• Added by Baddeley in 2000
• Temporary store integrating information from other components
• Links working memory to long-term memory
• Limited capacity (about 4 chunks)
• Creates integrated episodes combining different types of information

Supporting evidence:

Dual-task studies (Baddeley, 1966) provide strong support. Participants performed two tasks simultaneously using the same component (e.g., two visual tasks) - performance decreased. When tasks used different components (e.g., one visual, one verbal), performance remained good. This suggests separate slave systems exist.

The word-length effect supports the phonological loop. People remember more short words than long words because the phonological loop holds what you can say in approximately 2 seconds. Long words take longer to rehearse, reducing capacity.

Brain scanning studies show different areas activate when processing verbal information (left hemisphere) versus visual information (right hemisphere), supporting separate slave systems.

Case study KF (Shallice & Warrington, 1970) had brain damage affecting his verbal STM but his visual STM was intact. His LTM was also unaffected. This supports the idea of separate verbal and visual components rather than a single STM store.

Evaluation:

Strengths:

• Explains STM as an active process, not just a temporary store
• Supported by dual-task experiments
• Explains why we can do two tasks at once if they use different components
• More detailed than the multi-store model's account of STM
• Evidence from brain-damaged patients supports separate components

Weaknesses:

• Central executive is vague and not fully explained - scientists don't fully understand how it works
• Little evidence for the episodic buffer as it was added later
• Only explains STM/working memory, not the whole memory system
• Difficult to test the central executive experimentally

Comparing the two models

Similarities:

• Both propose separate components/stores for different types of information
• Both involve rehearsal processes
• Both supported by case studies of brain-damaged patients
• Both explain limited capacity of short-term storage

Differences:

• Multi-store model sees STM as a single store; working memory model divides it into multiple components
• Multi-store model is passive (information just passes through); working memory model is active (information is manipulated)
• Multi-store model covers the whole memory system (sensory, short-term, long-term); working memory model only explains STM
• Multi-store model emphasises rehearsal for transfer to LTM; working memory model focuses on active processing
• Working memory model explains how we perform tasks; multi-store model explains storage

The working memory model doesn't replace the multi-store model - it provides a more detailed explanation of the STM component within the broader multi-store framework.

Capacity, duration, and encoding in memory stores

Capacity research:

Jacobs (1887) used the digit span technique. Participants heard sequences of numbers or letters and had to recall them in order. The average span for digits was 9.3 items; for letters it was 7.3 items. This demonstrated STM's limited capacity.

Miller (1956) reviewed research and proposed the "magic number 7±2" - STM can hold between 5 and 9 items. He also introduced chunking - grouping information into meaningful units increases capacity. For example, remembering FBI-BBC-NHS as three chunks rather than nine letters.

Duration research:

Peterson and Peterson (1959) tested STM duration. Participants heard consonant trigrams (e.g., TGH) and counted backwards in threes to prevent rehearsal. After 3 seconds, recall was 80%; after 18 seconds, it dropped to 10%. This showed STM duration is very limited without rehearsal.

Bahrick et al. (1975) tested LTM duration by showing participants photographs from their school yearbooks. Recognition was 90% accurate after 14 years and 70% after 48 years, demonstrating LTM's potentially permanent duration.

Encoding research:

Baddeley (1966) investigated encoding in STM and LTM. Participants heard word lists and recalled them either immediately (STM) or after 20 minutes (LTM).

STM results: Acoustically similar words (cat, mat, sat) were harder to recall than acoustically dissimilar words, but semantic similarity made no difference. This shows STM encodes acoustically.

LTM results: Semantically similar words (big, large, huge) were harder to recall than semantically dissimilar words, but acoustic similarity made no difference. This shows LTM encodes semantically.

Worked examples

Example 1: 2-mark question

Question: Outline one difference between short-term memory and long-term memory. (2 marks)

Mark scheme answer: One difference is capacity. Short-term memory has a limited capacity of approximately 7±2 items (1 mark), whereas long-term memory has unlimited capacity and can store vast amounts of information (1 mark).

Examiner note: You need to clearly identify the difference (e.g., capacity, duration, encoding) and then explain how it differs between the two stores. Both marks require accurate detail.

Example 2: 4-mark question

Question: Describe the multi-store model of memory. (4 marks)

Mark scheme answer: The multi-store model proposed by Atkinson and Shiffrin describes memory as consisting of three separate stores (1 mark). Information first enters the sensory register where it lasts for milliseconds unless attended to (1 mark). Information that receives attention passes to short-term memory, which has limited capacity (7±2 items) and duration (18-30 seconds) (1 mark). Through maintenance rehearsal, information can transfer to long-term memory, which has unlimited capacity and potentially permanent duration (1 mark).

Examiner note: Describe questions require accurate detail. Cover the main components and processes. Don't evaluate - save criticism for "evaluate" questions.

Example 3: 6-mark question

Question: Evaluate the working memory model. (6 marks)

Mark scheme answer: One strength is support from dual-task studies. Baddeley found that participants could perform a verbal and visual task simultaneously with little decrease in performance, but two verbal tasks caused interference (AO2: 2 marks). This supports the existence of separate slave systems for verbal and visual information (AO3: 1 mark).

However, the central executive is poorly understood and not fully explained. The model describes what it does but not how it works (AO2: 2 marks). This makes it difficult to test scientifically and limits the model's explanatory power (AO3: 1 mark).

Examiner note: Evaluation requires both strengths and weaknesses. Use evidence (research studies, case studies) to support points. Link evidence to the model explicitly. Aim for elaborated points rather than many brief ones.

Common mistakes and how to avoid them

• Confusing the two models — Students often mix up features of the multi-store model and working memory model. Remember: working memory model only explains STM; multi-store model covers the whole memory system (sensory register, STM, and LTM).

• Describing when asked to evaluate — "Evaluate" means strengths and weaknesses, not just description. Use research evidence and explain whether it supports or challenges the model. Avoid just listing features of the model.

• Not providing enough detail — Stating "STM has limited capacity" gains minimal marks. Add specific details: "STM has limited capacity of approximately 7±2 items according to Miller's research."

• Forgetting to name researchers — Research evidence is stronger when you cite psychologists. Learn key names: Atkinson & Shiffrin (multi-store model), Baddeley & Hitch (working memory model), Peterson & Peterson (STM duration), HM (case study).

• Muddling capacity, duration, and encoding — These are three separate characteristics. Capacity = how much; duration = how long; encoding = what format. Don't confuse them in answers.

• Incomplete component descriptions — When describing working memory model components, include their function. Don't just list them. For example: "The phonological loop processes verbal and acoustic information through the phonological store and articulatory process."

Exam technique for "Memory: Models of Memory"

• Command word awareness — "Outline" requires brief, accurate description (2 marks = 2 points). "Describe" requires detailed description (4-6 marks = extended detail). "Evaluate" requires strengths, weaknesses, and evidence (must include AO3 analysis, not just AO2 evidence).

• Using research evidence effectively — Name the researcher(s), briefly describe the procedure, state the findings, and link explicitly to the model. For example: "Peterson and Peterson (1959) found STM duration is 18-30 seconds, which supports the multi-store model's claim that STM is a temporary store."

• Balance in evaluation answers — Include both strengths and weaknesses. A 6-mark evaluation should have at least two elaborated points (one strength, one weakness). Avoid writing five strengths and one rushed weakness in the final sentence.

• Marks per point — In extended writing, aim for elaborated points worth 2-3 marks each rather than many brief points worth 1 mark. Develop each point with evidence and explanation.

Quick revision summary

Memory models explain the structure and processes of human memory. The multi-store model (Atkinson & Shiffrin, 1968) proposes three separate stores: sensory register, short-term memory (capacity 7±2 items, duration 18-30 seconds, acoustic encoding), and long-term memory (unlimited capacity, permanent duration, semantic encoding). Information flows through attention and rehearsal. The working memory model (Baddeley & Hitch, 1974) provides a detailed explanation of STM with four components: central executive, phonological loop, visuo-spatial sketchpad, and episodic buffer. Both models are supported by research evidence and brain-damaged patients but have limitations requiring critical evaluation.