topic 7. Memory: Foundations, Processes, and Errors

Memory: Foundations, Processes, and Errors

Introduction to Human Memory

Memory is the process by which we encode, store, and retrieve information. It is not a static system; memory can change over time and is subject to errors, such as 'filling in the gaps' when information is missing. This adaptive feature helps us make sense of the world but can also lead to inaccuracies.

• Memory as Reconstruction: Memory is more like a Wikipedia page than a recording device; it can be edited by ourselves and others (Beth Loftus).

• Brains and Memory: Our brains often go beyond available information to construct a coherent understanding of events.

Foundations of Memory

Encoding, Storage, and Retrieval

• Encoding: The initial recording of information.

• Storage: Saving information for future use.

• Retrieval: Recovering stored information for use.

Three-Stage Model of Memory

This model proposes three types of memory, each differing in span and duration. Information must pass through all stages to be remembered:

• Sensory Memory → Short-Term Memory (STM) → Long-Term Memory (LTM)

Sensory Memory

• Stores brief sensory events (sights, sounds, tastes).

• Each sense has its own sensory memory:

  • Iconic memory: Visual, lasts less than 1 second.

  • Echoic memory: Auditory, lasts 2-3 seconds.

• Acts as a high-precision snapshot; unless transferred, information is lost quickly.

Short-Term Memory (STM)

• Limited capacity system; retains information for up to 30 seconds unless rehearsed.

• Capacity: 7 ± 2 items (the 'magic number 7').

• Information is either discarded or transferred to LTM.

Extending STM Capacity

• Chunking: Organizing information into meaningful groups increases STM span.

• Example: Grouping letters into familiar acronyms or words.

Rehearsal: Transferring from STM to LTM

• Rehearsal: Repeating information to consolidate memory.

• Maintenance rehearsal: Simple repetition; less effective for long-term retention.

• Elaborative rehearsal: Organizing and linking information meaningfully; more effective for LTM transfer.

Working Memory

• Active, temporary memory stores that manipulate and rehearse information.

• Includes a central executive processor for reasoning and decision-making.

• Acts as a 'mental whiteboard.'

Long-Term Memory (LTM)

• Continuous, potentially lifelong storage of information.

• No known capacity limit; analogous to a computer's hard drive.

• Distinguished from STM by cases of amnesia (anterograde vs. retrograde).

Types of Long-Term Memory

Type	Subtypes	Description
Declarative (Explicit)	Semantic, Episodic	Conscious recollection of facts/events
Non-declarative (Implicit)	Procedural, Priming	Unconscious memory for skills and conditioned responses

Declarative Memory

• Semantic memory: General knowledge (e.g., facts, concepts).

• Episodic memory: Personal experiences (e.g., first day at university).

Non-declarative Memory

• Implicit memory: Influence of past experience on behavior, without conscious awareness.

• Procedural memory: How to perform tasks (e.g., tying shoes).

• Priming: Activation of stored information to facilitate new learning or identification.

Neuroscience of Memory

Brain Structures and Memory

• Karl Lashley & Engram: Memory traces are distributed throughout the brain.

• Hippocampus: Critical for memory consolidation and encoding new declarative memories; damage impairs new memory formation.

• Amygdala: Involved in emotional memories (e.g., trauma, phobias).

Long-Term Potentiation (LTP)

• Neural pathways become more easily excited with repeated activation ('neurons that fire together, wire together').

• Synapses between neurons increase, and dendrites branch out, strengthening memory traces.

Forgetting: Causes and Mechanisms

Encoding Failures

• Information must be attended to in order to be encoded.

• Most experiences are never encoded (e.g., 'next-in-line effect').

• Self-reference effect: Better memory for information related to oneself.

• Stress: Reduces accuracy of eyewitness recall; can focus attention but also increase errors.

• Other factors: Own-age bias, cross-race effect.

Retrieval Failures

• Decay: Memory fades over time.

• Interference: Competition between memories impairs retrieval.

  • Proactive interference: Old information interferes with new learning.

  • Retroactive interference: New information interferes with retrieval of old memories.

Amnesia

• Anterograde amnesia: Inability to form new memories after trauma; often due to hippocampal damage.

• Retrograde amnesia: Loss of memories for events prior to trauma.

Case Studies

• Henry Molaison (HM): Lost ability to form new explicit memories after hippocampus removal; could learn new skills (implicit memory intact).

• Clive Wearing: Severe anterograde and retrograde amnesia after encephalitis; retained procedural memory (could play piano).

Retrieving Memories

• Recall: Accessing information without cues (e.g., essay questions).

• Recognition: Identifying previously learned information (e.g., multiple-choice questions).

• Tip-of-the-tongue phenomenon: Knowing information but being temporarily unable to retrieve it; often resolved with cues.

Levels of Processing Theory

• The depth of processing during encoding affects memory retention.

• Shallow processing: Focus on physical/sensory aspects (e.g., rote memorization).

• Deep processing: Focus on meaning and connections; leads to better retention.

Encoding Specificity

• Memory retrieval is more effective when conditions at retrieval match those at encoding.

• Context-dependent learning: Better recall in the same environment as learning (e.g., classroom).

• State-dependent learning: Better recall when in the same physiological state (e.g., sober vs. intoxicated).

Flashbulb Memory

• Vivid, detailed memories of atypical, emotionally charged events.

• Often act as generational reference points (e.g., 9/11, moon landing).

• Not necessarily accurate, but strongly felt.

Memory as Reconstruction

• Memories are reconstructed, not replayed; subject to change over time.

• Influenced by cognitive structures (schemas, scripts) and post-event information.

• Important implications for legal settings (e.g., eyewitness testimony).

Schemas & Scripts

• Organized knowledge structures that help fill in gaps in memory.

• Can distort memory to fit expectations (e.g., recalling omitted details to match a 'robbery script').

• Stereotypes can also bias memory recall.

Suggestibility and False Memories

• Suggestibility: External information can create false memories.

• Memories are fragile and vulnerable to suggestion, especially in eyewitness testimony.

The Misinformation Effect

• Post-event information can alter or become incorporated into original memory (Loftus, 1974).

• Leading questions can change what is remembered (e.g., "How fast were the cars going when they smashed into each other?").

False Memories

• Studies (Loftus, 1997; Hyman et al., 1997) show that people can be led to remember events that never happened.

• Laboratory induction of false memories includes events like being lost, attacked by a dog, or meeting fictional characters at real places.

• Mandela Effect: Collective false memories (e.g., misremembering brand logos or cultural details).

Memory Hacker Study (Shaw & Porter, 2015)

• Controversial study: 70% of participants were convinced they committed a crime after repeated interviews.

Eyewitness Misidentification

• Leading cause of wrongful convictions.

• Line-up procedures: Witnesses identify suspects from a group containing the suspect and distractors (foils).

• Errors can arise from memory distortions, stress, and suggestibility.

Case Example: Ronald Cotton

• Illustrates the dangers of eyewitness misidentification and the importance of understanding memory errors in the justice system.

Additional info: This guide integrates foundational concepts, key studies, and real-world applications to provide a comprehensive overview of memory for psychology students.