Comprehensive Study Notes: Human Memory (Topic 7)

Human Memory: Foundations and Processes

Introduction to Human Memory

Memory is the process by which we encode, store, and retrieve information. It is not static and can change over time. Our brains often "fill in the gaps" in memory, which is generally adaptive but can lead to errors. Memory is reconstructive, meaning it is influenced by both internal and external factors.

• Encoding: Initial recording of information.

• Storage: Information saved for future use.

• Retrieval: Recovery of stored information.

Models and Types of Memory

Three-Stage Model of Memory

This model proposes three distinct 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

Sensory memory stores brief sensory events, such as sights, sounds, and tastes. Each sense has its own sensory memory, which is very brief and high in precision.

• Iconic memory: Visual system, < 1 second

• Echoic memory: Auditory system, 2-3 seconds

• Acts as a snapshot that stores sensory information

• Unless transferred to other types of memory, it is lost

Short-Term Memory (STM)

STM is a limited capacity memory system where information is retained for up to 30 seconds unless actively maintained through rehearsal.

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

• Information is either discarded or stored in LTM

Extending STM Capacity

STM span can be extended by chunking, which involves organizing large bodies of information into smaller, meaningful groups.

• Example: Grouping letters into familiar acronyms or words

Rehearsal: Transferring from STM to LTM

Rehearsal is the repetition of information that has entered STM, leading to memory consolidation.

• Maintenance rehearsal: Repeating stimuli in the same form

• Elaborative rehearsal: Organizing and linking stimuli in meaningful ways; more effective for transfer to LTM

Working Memory

Working memory is a set of active, temporary memory stores that manipulate and rehearse information. It includes a central executive processor involved in reasoning and decision-making, often described as a "mental whiteboard."

Long-Term Memory (LTM)

LTM is the continuous storage of information, potentially lasting decades or a lifetime. It has no known limit and is analogous to a computer's hard drive.

• Anterograde vs. Retrograde Amnesia: Evidence for distinction between STM and LTM

Types of Long-Term Memory

Type	Description	Example
Explicit (Declarative)	Conscious recollection of facts/events	Semantic (general knowledge), Episodic (personal events)
Implicit (Non-declarative)	Unconscious memory affecting behavior	Procedural (skills), Priming (faster identification)

Key Effects and Phenomena in Memory

The Serial Position Effect

The tendency to recall items at the beginning (primacy effect) and end (recency effect) of a list better than those in the middle. Odd or unique stimuli are remembered regardless of position.

Case Studies in Memory

• Henry Molaison (HM): Had hippocampus removed, resulting in inability to form new explicit memories but could learn new skills (mirror tracing task). Demonstrates distinction between explicit and implicit memory.

• Clive Wearing: Suffered from anterograde and retrograde amnesia due to encephalitis; could still play piano, showing preserved procedural memory.

Neuroscience of Memory

Brain Structures Involved

• Hippocampus: Critical for memory consolidation and encoding new declarative memories

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

Long-Term Potentiation (LTP)

LTP is a process where certain neural pathways become more easily excited as a new response is learned. "Neurons that fire together, wire together." Synapses between neurons increase, and dendrites branch out.

Forgetting: Causes and Mechanisms

Encoding Failures

Failure to encode information often results from lack of attention. Most events are never encoded. The self-reference effect shows we remember information better when it relates to us.

• Stress: Reduces accuracy of eyewitness recall and identification

• Own age bias and cross-race effect can also impair encoding

Retrieval Failure

• Decay: Information fades over time

• Interference: Loss of information due to competition with new information

• Proactive interference: Old information interferes with new

• Retroactive interference: New information interferes with old

Amnesia

• Anterograde amnesia: Inability to remember new information after trauma; often involves hippocampal damage

• Retrograde amnesia: Loss of memory for events prior to trauma

Retrieving Memories

• Recall: Accessing information without cues (e.g., short answer test)

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

• Tip-of-the-tongue phenomenon: Retrieval failure where information is known but cannot be recalled; may be retrieved by a related cue

Levels of Processing Theory

The depth of information processing during exposure is critical. Deeper, more meaningful processing leads to better memory retention.

• Shallow: Physical/sensory aspects (e.g., memorizing key terms)

• Deepest: Meaningful analysis and reflection

Encoding Specificity

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

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

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

Flashbulb Memory

Flashbulb memories are vivid records of atypical and emotionally charged events. They are easily retrieved but not always accurate. Examples include major historical events (e.g., 9/11, JFK assassination).

Memory Reconstruction and Suggestibility

Memory is Reconstructive

Memories change over time and can be influenced by cognitive "hardware" (schemas, scripts, stereotypes) and post-event information. This has important implications for legal settings.

Schemas & Scripts

Schemas and scripts are organized knowledge structures that help fill in memory gaps but can distort memory to conform with expectations. Stereotypes also influence memory.

Suggestibility and False Memories

Suggestibility refers to the effects of misinformation from external sources, leading to the creation of false memories. This is a critical area in eyewitness testimony.

• Misinformation effect: Post-event information alters original memory (Loftus, 1974)

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

• Mandela Effect: Collective false memories of events or details

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

• Memory Hacker (Shaw & Porter, 2015): 70% of participants convinced they committed a crime through suggestion

Eyewitness Memory and Legal Implications

Eyewitness Misidentification

Eyewitness misidentification is the leading cause of wrongful convictions. Line-up procedures involve identifying a suspect among foils or distractors, but memory errors and suggestibility can lead to mistakes.

Leading Cause	Percentage of DNA Exoneration Cases
Eyewitness misidentification	Highest
Forensic science	Lower
False confession	Lower
Informant	Lowest

• Case Example: Ronald Cotton, a case of eyewitness misidentification

Additional info: These notes expand on the original slides and text, providing definitions, examples, and context for key concepts in human memory, suitable for exam preparation in a college-level psychology course.