Welcome to the World of Memory!

Hello future psychologist! Memory is one of the most fascinating topics in cognitive psychology because it literally shapes who we are. It's not just about remembering facts for an exam; it’s how we store experiences, skills, and knowledge.

In this chapter, we will break down how information travels through our brains (the models), look at the different kinds of memories we hold, and explore the crucial practical application of memory research—like understanding why eyewitnesses sometimes get things wrong!

1. The Multi-Store Model of Memory (MSM)

The Multi-Store Model (MSM), proposed by Atkinson and Shiffrin (1968), is the foundational theory of memory. It suggests that memory is made up of three separate, interacting stores: the Sensory Register (SR), Short-Term Memory (STM), and Long-Term Memory (LTM).

Analogy: Think of the MSM like a factory floor with three different storage areas and specific rules for what gets kept where.

1.1 The Sensory Register (SR)

This is where information first enters the memory system from our senses (sight, sound, touch, etc.).

  • Coding: Information is stored in its original sensory format (e.g., visual input for what you see, auditory input for what you hear).
  • Capacity: Very high capacity, potentially unlimited. It takes in all sensory experience.
  • Duration: Extremely brief (less than half a second for visual information; about 2 seconds for auditory). If you don't pay attention to it, it vanishes.

1.2 Short-Term Memory (STM)

If we pay attention to information in the SR, it moves to the STM. This is the 'workbench' of the memory system, where we actively process information.

  • Coding: Primarily acoustically (by sound). Even if you read a list silently, you often repeat the sounds of the words in your head.
  • Capacity: Limited. George Miller famously suggested the 'Magic Number 7'—approximately 7 +/- 2 items (chunks) of information.
  • Duration: Short, about 18–30 seconds, unless the information is actively rehearsed (repeated).

💡 Memory Aid: To keep things in STM longer than 30 seconds, you need Maintenance Rehearsal (simply repeating the information). To move it to LTM, you need Elaborative Rehearsal (giving it meaning, linking it to existing knowledge).

1.3 Long-Term Memory (LTM)

When information is rehearsed elaboratively, it moves into LTM—our permanent, potentially limitless store.

  • Coding: Primarily semantically (by meaning). You remember the general idea or concept, not usually the exact wording.
  • Capacity: Potentially unlimited.
  • Duration: Potentially permanent (lifetime).
Quick Review: MSM Features

| Store | Coding | Capacity | Duration |
| :--- | :--- | :--- | :--- |
| SR | Sensory specific | Very high | Less than 2 seconds |
| STM | Acoustic | 7 +/- 2 chunks | 18–30 seconds |
| LTM | Semantic | Unlimited | Lifetime |

2. The Working Memory Model (WMM)

Don't worry if the MSM seemed too simple! Psychologists realised STM wasn't just a passive box; it's active. Baddeley and Hitch (1974) proposed the Working Memory Model (WMM) to explain how STM functions when we are actively working on information (e.g., mentally calculating a tip or listening to music while reading).

The WMM describes STM as a dynamic system made up of four main components.

2.1 The Components of WMM

The WMM is controlled by the 'boss' and has three 'slave systems' that deal with specific types of information.

1. Central Executive (CE)

This is the monitoring and control system. It allocates resources to the slave systems and processes all sensory modalities. It's the brain's attention control center.

2. Phonological Loop (PL)

Deals with auditory information (sound and spoken material). It's sometimes called your 'inner ear' and 'inner voice'.

  • Phonological Store: Stores what you hear (like a temporary echo).
  • Articulatory Control System: Allows for mental rehearsal (your 'inner voice' repeating phone numbers).

3. Visuo-Spatial Sketchpad (VSS)

Deals with visual and spatial information (what things look like and where they are). It's your 'inner eye' used for navigation or rotating an image in your head.

4. Episodic Buffer (EB)

Added later (in 2000), this component acts as a temporary store that integrates information from the CE, the PL, the VSS, and LTM. It helps create a single, integrated ‘episode’ of experience (like remembering the sequence of events in a film).

2.2 Features of the WMM: Coding and Capacity

Unlike the MSM, WMM features vary greatly between components.

  • Central Executive: Codes information broadly, capacity is very limited.
  • Phonological Loop: Codes acoustically. Capacity is limited by duration—what you can say in about two seconds.
  • Visuo-Spatial Sketchpad: Codes visually/spatially. Capacity is limited, generally around 3–4 objects.
  • Episodic Buffer: Codes multidimensionally (combining sight, sound, etc.). Capacity is around 4 chunks.
Key Takeaway: WMM vs. MSM

The WMM explains dual task performance. You can successfully complete a visual task (using VSS) and a verbal task (using PL) simultaneously because they use separate 'slave systems'. However, you cannot easily complete two visual tasks at once, as they compete for the limited resources of the VSS.

3. Types of Long-Term Memory

LTM is not just one simple filing cabinet; it has specialised sections. Tulving (1972) suggested there are three main types of LTM, which fall under two categories: Declarative (knowing *that*) and Non-Declarative (knowing *how*).

3.1 Episodic Memory (Declarative)

This is the memory for specific personal events, experiences, and contexts. It is like your mental diary.

  • Example: Remembering what you ate for dinner last night, or the exact moment you received your exam results.
  • These memories require conscious effort to recall and are time-stamped (you know *when* they happened).

3.2 Semantic Memory (Declarative)

This is the memory for facts, knowledge, concepts, and meanings. It is like your mental encyclopaedia or dictionary.

  • Example: Knowing that Paris is the capital of France, or that a car has four wheels.
  • These memories are not time-stamped. You know the information, but you don't need to remember where or when you learned it.

3.3 Procedural Memory (Non-Declarative)

This is the memory for how to perform physical skills or actions. It is automatic and unconscious.

  • Example: Knowing how to ride a bicycle, tie your shoelaces, or play the piano.
  • These memories are often difficult to explain verbally, and recalling them doesn't require conscious thought (they are non-declarative).

Did you know? Research using brain scans (neuroimaging) supports this distinction, showing that different areas of the brain are active when recalling episodic vs. semantic or procedural memories.

4. Memory in the Real World: Eyewitness Testimony (EWT)

Eyewitness Testimony (EWT) is the evidence provided by people who witnessed a crime or accident. Cognitive psychologists have shown that this memory is highly fallible (prone to error).

4.1 Factors Affecting the Accuracy of EWT

A. Leading Questions

A leading question is a question that suggests a desired answer because of the way it is phrased. This can distort memory recall.

  • Classic Study Connection: Loftus and Palmer (1974) showed participants a film of a car accident and asked them to estimate the speed the cars were going. The critical verb used (e.g., 'smashed', 'collided', 'hit') significantly affected their speed estimates. The verb 'smashed' led to the highest speed estimate and the highest chance of falsely reporting seeing broken glass (which wasn't there).
B. Post-Event Discussion (PED)

This occurs when co-witnesses discuss the details of an event after it has happened. This discussion can contaminate or alter their original memory.

  • Explanation: Witnesses may combine information (misinformation) from other people with their own memories, leading to a single, inaccurate 'memory' that they genuinely believe is true (a process called memory conformity).

4.2 The Cognitive Interview (CI)

The CI is a police technique developed by Fisher and Geiselman (1992) designed to improve the accuracy of EWT by using psychological principles of memory retrieval. It encourages the witness to relax and provides retrieval cues.

The CI uses four main techniques:

1. Context Reinstatement

  • The interviewer asks the witness to mentally recreate the environment and emotional state they were in at the time of the event (e.g., "What was the weather like? How were you feeling?").
  • Why it works: This acts as a retrieval cue; memories are often linked to the context in which they were formed (context-dependent forgetting).

2. Report Everything

  • Witnesses are encouraged to report every detail of the event, even if it seems irrelevant or trivial.
  • Why it works: Trivial details might trigger other, more important memories, or seemingly minor details might later prove relevant.

3. Recall from a Changed Perspective

  • The witness is asked to describe the event as if they were seeing it from a different viewpoint (e.g., from across the street, or from the perpetrator's view).
  • Why it works: This disrupts the use of schemas (pre-existing expectations) and helps overcome common retrieval biases.

4. Recall in Reverse Order

  • The witness is asked to recount the event in a different chronological order, perhaps from the end to the beginning.
  • Why it works: This prevents the witness from relying on expectations (schemas) about how the event must have happened, forcing deeper recall.
Enhancing the CI: The Enhanced Cognitive Interview

An enhanced version of the CI often focuses more on social dynamics, such as establishing rapport with the witness, knowing when to make eye contact, and reducing anxiety, which further improves recall accuracy.

Key Takeaway: EWT

Memory is a reconstructive process, not a video recording. The CI is a valuable tool because it uses proven psychological techniques to maximise the chance of an accurate memory retrieval, minimizing the effects of leading questions or post-event contamination.