Memory: Foundations, Processes, and Applications in Psychology

Topic 7: Memory

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 can be influenced by various factors and is not a perfect recording of events.

• Encoding: Initial recording of information.

• Storage: Information saved for future use.

• Retrieval: Recovery of stored information.

Three-Stage Model of Memory

Overview

Memory is divided into three main types, 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, information 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.

• 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: Considering and organizing information, linking stimuli in meaningful ways; more effective for transfer to LTM

Working Memory

Working memory is a set of active, temporary memory stores that actively 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. The distinction between anterograde and retrograde amnesia evidences the separation from STM.

Types of Long-Term Memory

Type	Description	Examples
Explicit (Declarative)	Conscious recollection of facts and events	Semantic (general knowledge), Episodic (personal events)
Implicit (Non-declarative)	Memory without conscious awareness	Procedural (skills), Priming (faster identification)

The Serial Position Effect

The serial position effect describes 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 (implicit memory).

• Clive Wearing: Suffered from anterograde and retrograde amnesia due to encephalitis; could still play piano, showing distinction between declarative and non-declarative memory.

Neuroscience of Memory

Brain Structures

• Hippocampus: Involved in memory consolidation and initial encoding; damage impairs new declarative memory formation.

• Amygdala: Involved in emotional memories, such as traumatic experiences and phobias.

Long-Term Potentiation

Long-term potentiation (LTP) is a process where certain neural pathways become more easily excited as a new response is learned. This is summarized by the phrase "neurons that fire together, wire together."

• Synapses between neurons increase, dendrites branch out

Forgetting: Encoding and Retrieval Failures

Encoding Failures

Encoding requires attention; most events are never encoded. The self-reference effect shows we remember information better when it relates to us. Stress and biases (own age, cross-race effect) can reduce encoding accuracy.

Factor	Effect
Stress	Reduces accuracy of eyewitness recall
Own age bias	Better memory for people of similar age
Cross-race effect	Difficulty distinguishing faces of other races

Retrieval Failures

• Decay: Information fades over time

• Interference: Loss 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: Knowing information but unable to retrieve it; sometimes helped by related cues

Levels of Processing Theory

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

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

• Deepest: Analyzing meaning and reflecting on relationships to existing knowledge

Encoding Specificity

Memory retrieval is improved when the 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., under influence of alcohol)

Flashbulb Memory

Flashbulb memories are vivid records of atypical and emotionally significant events. They are often more easily retrieved but not necessarily accurate.

• Examples: Assassinations, first Moon landing, 9/11 attacks

Memory is Reconstructive

Memory changes 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.

• Example: Robbery script study—participants recalled omitted details to fit the script

• Stereotypes can also influence memory

Suggestibility and False Memories

Suggestibility

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.

The Misinformation Effect

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

• Example questions: "How fast were the cars going when they hit each other?"

• Leading questions can change what is remembered

False Memories

• Loftus (1997): 25% of participants remembered an implanted memory after two interviews

• Hyman et al. (1997): 27% accepted a false memory after suggestion

Mandela Effect

The Mandela Effect describes widespread false memories shared by many people, such as misremembering logos or events.

Laboratory Induction of False Childhood Memories

Researchers have successfully implanted a variety of false memories, including traumatic ones (e.g., meeting Bugs Bunny at Disneyland).

Memory Hacker (Shaw & Porter, 2015)

Controversial study showing that 70% of participants could be convinced they committed a crime through repeated interviews.

Eyewitness Misidentification

Eyewitness misidentification is the leading cause of wrongful convictions. Line-up procedures involve identifying a suspect among foils or distractors.

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

• Example: Ronald Cotton case

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