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 process helps us make sense of the world but can also lead to inaccuracies.

• Memory is reconstructive: Like a Wikipedia page, it can be edited by ourselves and others (Loftus).

• Brains use available information and prior knowledge to interpret and remember 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): < 1 second

  • Echoic memory (auditory): 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: Repetition of 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/behaviors

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: Unconscious influence of past experiences.

• Procedural memory: Skills and habits (e.g., tying shoes).

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

Neuroscience of Memory

Brain Structures Involved

• Hippocampus: Essential 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, dendrites branch out.

Why Do We Forget?

Encoding Failures

• Attention is required for encoding; most events are never encoded.

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

• Stress can reduce accuracy of encoding (e.g., eyewitness recall).

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

Retrieval Failure

• Decay: Memory fades over time.

• Interference: Competition from other information.

  • 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 before trauma.

Case Studies

• Henry Molaison (HM): Removal of hippocampus led to inability to form new explicit memories, but could learn new skills (implicit memory intact).

• Clive Wearing: Severe anterograde and retrograde amnesia after encephalitis; could still play piano, showing distinction between memory types.

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 temporarily unable to retrieve it; often resolved with cues.

Levels of Processing Theory

• Depth of processing during learning affects retention.

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

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

Encoding Specificity

• Memory retrieval is improved 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 internal state matches learning state (e.g., mood, intoxication).

Flashbulb Memory

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

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

• Not always accurate, but strongly felt.

Memory is Reconstructive

• Memories are not exact replicas; they are reconstructed and can change over time.

• Influenced by cognitive structures (schemas, scripts, stereotypes) 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., robbery script study).

• Stereotypes can also bias memory recall.

Suggestibility and False Memories

• Suggestibility: External information can create false memories.

• Memories are 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 show that people can develop memories for events that never happened (e.g., being lost in a mall, spilling punch at a wedding).

• Laboratory studies have implanted false childhood memories (e.g., meeting Bugs Bunny at Disneyland).

• Mandela Effect: Collective false memories shared by groups (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 covers key concepts from the psychology of memory, including foundational models, types of memory, neuroscience, forgetting, reconstructive processes, and the implications for real-world issues such as eyewitness testimony and false memories.