Memory Research Overview

Early Research into Memory

• Early researchers focused on the role of the brain in memory formation, but the exact changes were not fully understood.
• The concept of a "memory trace" or "engram" was introduced to describe hypothetical brain alterations related to stored memories.
• Major questions arose about how memories are localized in the brain and how neurons change during the formation of memory.
• Ivan Pavlov's research into conditioned responses influenced early memory theories.
• Pavlov's theory, while valuable, had limitations in fully explaining the brain's mechanisms involved in memory.

Imperfect Memories & False Memories

• Several factors contribute to false memories:
  • Misinformation effect
  • Preexisting schemas
  • Source confusion
  • Imagination inflation
  • Blending fact and fiction
  • Suggestion

Amnesia and Memory Processing

• Studying amnesia helps scientists understand brain regions involved in memory.
• Retrograde amnesia disrupts memory consolidation, affecting past memories.
• Anterograde amnesia disrupts the formation of new memories.
• The case of H.M. (Henry Molaison) is a well-known example of anterograde amnesia.
• Brenda Milner and Suzanne Corkin's research on H.M. highlighted the distinct brain regions involved in explicit and implicit memories.

Key Researchers and Their Findings

• Karl S. Lashley concluded that memories are distributed throughout the brain rather than localized.
• Richard F. Thompson demonstrated that memory for simple conditioned reflexes is localized in the brain.
• Eric Kandel's research revealed that new memory formation leads to structural and functional changes in neurons.
• Long-term potentiation, a lasting increase in synaptic strength, is crucial in memory consolidation.

Dementia and Alzheimer's Disease

• Dementia is a progressive decline in cognitive functions, including memory and reasoning.
• Alzheimer's disease (AD), the most common cause of dementia, is characterized by plaques and tangles in the brain.

Brain Structures and Memory

• Several brain structures are involved in memory processes:
  • The hippocampus plays a key part in memory consolidation.
  • The cerebellum is involved in motor memory and procedural learning.
  • The amygdala processes emotional memories.
  • The frontal lobes, including the prefrontal cortex, are crucial for working memory and decision-making.
  • The medial temporal lobes are important for declarative memory.

Neuronal Changes in Response to Sound

• Studies using Aplysia (sea snails) demonstrate how neurons change in response to repeated stimuli, leading to learned behaviors (gill withdrawal response).
• These changes include an increase in the number of neuron branches and synapses.
• This process, known as long-term potentiation, strengthens synaptic connections.
• Similar changes occur in other species, suggesting a common biological basis for learning and memory.

Source Confusion

• Source confusion arises when the origin of a memory is forgotten or misattributed.
• It can contribute to the misinformation effect, where false information provided after an event gets mixed into the original memory.
• Research highlights the high confidence people can have in false memories, often equaling their confidence in accurate memories.

Schemas and Memory Distortions

• Schemas, pre-existing mental frameworks, can shape and distort memories.
• They can lead to the inclusion of schema-consistent details, even if they were not present in the original experience.

Reliability of Memory

• Memories are not simply recordings, but rather reconstructions influenced by existing knowledge and understanding of the world.
• This reconstructive process can lead to inaccuracies and distortions in memory.

False Memory Example

• Doctored images can influence memory, causing people to incorporate false details into their recollections of real events.

Factors Contributing to False Memories (Table 6.3)

• Misinformation effect: incorrect information provided after an event can distort memory.
• Schema distortion: filling in missing details with schema-consistent information can lead to error.
• Source confusion: forgetting the true source of a memory can lead to inaccurate attribution.
• Imagination inflation: vividly imagining an event can increase confidence that it happened, even if it didn't.
• False familiarity: repeated imagining of an event can increase feelings of familiarity, leading to a false belief that it occurred.
• Blending fact and fiction: using vivid details to support a false memory can make it seem more believable.
• Suggestion: highly suggestive techniques like hypnosis can create false memories.

Eyewitness Misidentification: Convicting the Innocent

• Ronald Cotton's story underscores the fallibility of eyewitness testimony and the potential for misidentification.
• The case illustrates that eyewitness confidence can be a poor indicator of memory accuracy.

Schemas and Memory Distortions: The Influence of Existing Knowledge on What is Remembered

• Pre-existing knowledge in the form of schemas can significantly influence our memories.
• A study by Brewer and Treyens demonstrated that participants falsely remembered schema-consistent objects in a psychology professor's office, highlighting how schemas can contribute to memory distortions.

Forming False Memories

• False memories of events that never happened can be created through various techniques.
• Research on false memories has demonstrated that imagination can play a significant role in their formation.

The Lost-in-the-Mall Experiment

• Loftus and Pickrell's classic study used the "Lost-in-the-Mall" technique to induce false memories in participants.
• The study showed that participants could be led to believe they had experienced an event that never happened, even with vivid details.

Imagination Inflation

• Imagination inflation is the phenomenon where vividly imagining an event increases confidence that it actually occurred.
• Repeatedly imagining an event can contribute to its perceived familiarity and create false memories.

Memory: Key Processes and Stages

• Memory is a complex process that involves encoding, storage, and retrieval.
• The Stage Model of Memory describes three distinct memory stages: sensory memory, short-term memory, and long-term memory.

Sensory Memory

• Briefly stores sensory information from the environment.
• Each sensory modality has its own sensory memory.
• Visual sensory memory lasts for about half a second.

Short-Term Memory (STM)

• Temporarily stores information from sensory memory and retrieved information from long-term memory.
• Capacity is limited, typically to a few units of information.
• Maintenance rehearsal keeps information active in STM.
• Without active rehearsal, information fades from STM within 20 seconds.

Working Memory

• The active manipulation of information in STM.
• It's thought to consist of three components: phonological loop, visuospatial sketchpad, and central executive.

Long-Term Memory (LTM)

• Stores information potentially indefinitely.
• Elaborative rehearsal, focusing on the meaning of information, helps encode it into LTM.
• Information in LTM is organized and associated with related groups for easier retrieval.
• The semantic network model portrays LTM as a complex network of associations.

Retrieval

• The process of accessing information stored in LTM.
• Retrieval cues are hints or prompts that trigger recall.
• Retrieval cue failure occurs when adequate or missing retrieval cues make recall difficult, exemplified by the "tip-of-the-tongue" phenomenon.
• Recall, cued recall, and recognition are strategies for testing retrieval.

Types of Long-Term Memory

• Explicit memory (declarative memory): memory with conscious recall
  • Episodic memory: memories of personal events.
  • Semantic memory : memories of facts and general knowledge.
• Implicit memory (nondeclarative memory): memory without conscious recall
  • Procedural memory: memory for skills and actions.

Forgetting

• The inability to recall previously available information.
• Factors contributing to forgetting:
  • Encoding failure: information not properly encoded into LTM.
  • Retrieval cue failure: lack of adequate or missing retrieval cues.
  • Decay theory: information fades over time if not used.
  • Retroactive interference: new information interferes with recall of old information.
  • Proactive interference: older information interferes with recall of new information.
  • Suppression: conscious effort to avoid recalling specific information.
  • Repression: unconscious effort to avoid recalling specific information.

Hermann Ebbinghaus

• Identified a basic pattern of forgetting: rapid initial loss of information followed by a more stable retention of remaining information.