Memory: Constructing and Reconstructing Our Pasts (Chapter 7 Study Notes)

Memory: Constructing and Reconstructing Our Pasts

Introduction to Memory

• Memory is defined as the retention of information over time.

• Memory can be surprisingly accurate in some cases and surprisingly flawed in others, a phenomenon known as the memory paradox.

• Memories are not static; they can change over time due to various influences.

Reconstructive Nature of Memory

• Remembering is an active process where we reconstruct memories, not simply retrieve them as exact copies.

• We often "fill in the gaps" in our memories, which is generally adaptive but can lead to errors.

• Example: When recalling a walk, you may remember seeing yourself from an external perspective, which is a manufactured detail.

Models and Systems of Memory

Information-Processing Approach

• This approach uses computer science analogies to understand memory, referring to hardware (brain structures) and software (learned strategies).

• The Atkinson-Shiffrin model (1960s) describes three memory systems: sensory, short-term, and long-term memory.

The Three Memory Systems

System	Function	Capacity	Duration	Information Lost Through
Sensory Memory	Temporary storage for sensory information	Large	Visual: ~0.5-1 sec; Auditory: 5-10 sec	Decay, Displacement
Short-Term Memory (STM)	Brief storage for immediate use	About 7 items (5-9)	5-20 seconds without rehearsal	Decay, Displacement, Interference
Long-Term Memory (LTM)	Relatively permanent storage	Virtually unlimited	From minutes to a lifetime	Encoding failure, Motivated forgetting, Retrieval failure

Types of Sensory Memory

• Iconic memory: Visual sensory memory, lasting about one second.

• Echoic memory: Auditory sensory memory, lasting 5–10 seconds.

Short-Term Memory (STM)

Characteristics of STM

• STM retains information for limited durations (5–20 seconds).

• Information can be lost through decay (fading over time) or interference (competition with other information).

Types of Interference

• Retroactive interference: New learning interferes with old memories.

• Proactive interference: Old memories interfere with new learning.

• Interference is more likely when old and new information are similar.

Capacity and Working Memory

• The span of STM in adults is 5–9 items (Magic Number 7 ± 2).

• Working memory refers to the ability to hold and manipulate information currently being processed.

• Chunking helps extend STM by grouping information into meaningful units (e.g., grouping letters into acronyms).

Rehearsal and Levels of Processing

• Rehearsal (mental or verbal repetition) extends STM duration.

• Maintenance rehearsal: Simple repetition.

• Elaborative rehearsal: Linking new information to existing knowledge; more effective for long-term retention.

• According to the levels of processing model, deeper processing (semantic) leads to better recall than shallow processing (visual or phonological).

Long-Term Memory (LTM)

Characteristics of LTM

• LTM is a relatively permanent store of information, including facts, experiences, and skills.

• Some memories may last a lifetime (permastore).

Serial Position Effect

• Primacy effect: Better recall for items at the beginning of a list (due to rehearsal and encoding into LTM).

• Recency effect: Better recall for items at the end of a list (still in STM).

• Poorer recall for middle items due to lack of rehearsal and encoding.

Types of Long-Term Memory

Type	Description	Subtypes
Explicit (Declarative)	Intentional recall; conscious awareness	Semantic (facts), Episodic (events)
Implicit (Nondeclarative)	Unintentional recall; no conscious awareness	Procedural (skills), Priming, Conditioning, Habituation

• Explicit memory: Includes semantic (facts) and episodic (personal events) memory.

• Implicit memory: Includes procedural (skills and habits) and priming (increased identification of objects/words after prior exposure).

Processes of Memory

Encoding

• Encoding is the process of getting information into memory.

• Attention is crucial for effective encoding; not all encountered information is encoded.

• Mnemonics (e.g., rhymes, songs, method of loci) aid encoding by linking new information to existing knowledge.

Storage

• Storage is the process of maintaining information in memory.

• Depends on interpretation and expectations; schemas (organized knowledge structures) help fill in gaps but can also lead to distortions and biases.

Retrieval

• Retrieval is accessing information from LTM.

• Memory retrieval is reconstructive and may not match the original experience.

• Failures of retrieval are a common cause of forgetting.

• Retrieval cues (hints) can facilitate recall.

Measuring Memory

• Recall: Generating previously remembered information (requires generating and verifying the answer).

• Recognition: Identifying previously learned information from options (easier than recall).

• Relearning: Reacquiring knowledge more quickly than initial learning.

Tip-of-the-Tongue Phenomenon

• Occurs when retrieval fails despite a strong feeling of knowing the information.

• Often resolved with the help of related cues.

Improving Memory

Law of Distributed vs. Massed Practice

• Distributed practice (spreading study sessions over time) is more effective than massed practice (cramming).

• This is one of the most robust findings in psychology.

Encoding Specificity

• Memory is improved when retrieval conditions match encoding conditions.

• Two types: context-dependent learning (same environment) and state-dependent learning (same physiological/psychological state).

State-Dependent Learning

• Recall is better when internal states (e.g., mood, physiological state) at retrieval match those at encoding.

• Example: Students perform better on exams when tested in the same classroom where they learned the material.

Memory Disorders and the Brain

Amnesia

• Retrograde amnesia: Loss of past memories.

• Anterograde amnesia: Inability to form new memories.

• Generalized amnesia (loss of all past memories) is rare.

• Anterograde amnesia is more common in brain damage than retrograde amnesia.

Case Study: H.M.

• Underwent surgery for epilepsy; both hippocampi removed.

• Experienced mild retrograde and severe anterograde amnesia.

• Could not form new explicit memories but retained implicit memory (e.g., learning new motor skills).

Emotional Memory

• The amygdala stores emotional components of memories, especially fear.

• The hippocampus helps recall the factual details of events.

• Both structures interact to form emotional memories.

Amygdala and Hippocampus: Distinct Roles

• Damage to the amygdala impairs emotional recall but not factual recall.

• Damage to the hippocampus impairs factual recall but not emotional recall.

• Both are necessary for full memory of emotional events.

*Additional info: Conditioning and habituation are also considered forms of implicit memory, as shown in the memory subtypes diagram.*