Lecture 09: '

Definition of memory: Record of past experiences retained for future use.
Learning: The process by which memories are established.
- Behaviorists: Focused on learning processes and principles; often labeled as learning theorists.
- Cognitive Psychologists: Emphasized memory, studying factors influencing memory, and proposing theories explaining memory variations.
Memory's significance in introductory cognitive psychology courses.

Memory varies in accessibility over time.
- Primary Memory (William James): Equivalent to modern short-term memory (STM).
- Secondary Memory (William James): Equivalent to modern long-term memory (LTM).
Main question: Why are some memories accessible long term while others are not?

Proposed by Atkinson and Shiffrin (1968).
Term “modal model” signifies its historical acceptance as the standard theory of memory.
Reasons for studying the modal model:
- Influential in psychological theories, still referenced.
- Provides context for understanding later theories distinguishing STM from LTM.
- Offers insight into the scientific process of theory acceptance and revision.

Distinction between memory stores and memory performance:
- Short-term Memory (STM): Observable phenomenon of brief memory retention.
- Short-term Store (STS): Hypothetical construct explaining STM; its validity may be debated.
- Long-term Memory (LTM): Observable retention of information over extended periods.
- Long-term Store (LTS): Hypothetical construct for long-term memories; also a subject for debate.

The STS holds information briefly; LTS holds it indefinitely.
Memory trace decay in STS is linked to time passage:
- Loss of information follows a gradual decay similar to sensory memories.
Empirical findings:
- Brown-Peterson Paradigm (Brown, 1958; Peterson & Peterson, 1959): Recall declines sharply after 3 seconds of interference (50% accuracy) and 18 seconds (5% accuracy).
- Suggests STM trace duration is approximately 15 seconds.

Atkinson and Shiffrin (1968) posited:
- STS has a limited capacity (5-9 items).
- LTS has a virtually limitless capacity.
Miller's Magic Number (1956):
- Span of apprehension quantified as 7 ± 2 items through digit span tasks.

STS uses phonological/acoustic coding; LTS uses semantic/meaning-based coding.
- Conrad (1964): Participants had more errors recalling acoustically similar letters than visually similar ones.
- Wickelgren (1965): Tasks promoting sound-based processing led to poorer STM recall.
- Baddeley (1966): Short list recall reflects STS; longer list recall supports LTS.
- Manipulated list types, revealing the effects of phonological vs. semantic similarity on recall accuracy.

Rote rehearsal maintains STM trace:
- Refreshes memory and counters decay.
- Transfers information from STS to LTS, transforming phonological code to semantic code.
Supports findings from Bennett Murdock (1962) using serial position curves in memory recalls.

Murdock's experiment utilized word lists:
- Recency Effect: Better recall for items at the end due to availability in STS.
- Primacy Effect: Better recall at the beginning linked to rehearsal and transfer to LTS.
Glanzer and Cunitz (1966): Experimented with rehearsal prevention affecting recency and primacy effects.

Two memory stores (STS and LTS) explain variation in memory retention:
- STS: Brief retention, limited capacity, and acoustic representation.
- LTS: Indefinite retention, virtually limitless capacity, and semantic representation.
- Forgetting in LTS due to interference; STS forgetting linked to decay.