Short-term memory

How do short-term memory and long-term memory differ?

STM: brief storage, limited capacity

LTM: long-term storage, potentially unlimited capacity

What is STM used for?

Temporary storage for cognitive tasks like language processing and spatial navigation

What was Miller’s (1956) finding about STM capacity?

The “magic number” 7 ± 2 (people can remember 5-9 items in their STM at any given time)

What is the Digital Span Task?

A task where participants recall increasing sequences of digits to measure STM capacity

What happens with “superspan” lists

Recall probability decreases as list exceeds STM capacity, forming a serial position curve

What is serial position curve?

Better recall for items at the beginning (primacy effect) and end (recency effect) of a list

What does the primacy effect reflect?

Contribution of LTM (earlier items undergo rehearsal)

What does the recency effect reflect?

Contributions of STM (items that are still active in short-term store are recalled better)

What did Glanzer and Cunitz (1966) show with post-list distractor tasks?

Distractor tasks eliminate the recency effect, supporting the link between recency and STM

What did the case of HM show after temporal lobe removal? Miller (1966)

1. Normal STM

2. Impaired LTM (anterograde amnesia)

What did the case of KF show? Shallice and Warrington (1970)

1. Normal LTM

2. Severely impaired STM (digit span of 2)

What does both the case of HM and KF display?

Double dissociation between STM and LTM and that they are separate memory systems

What is Atkinson & Shiffrin’s (1968) Modal Model?

1. Information must pass through STM to enter LTM

2. Rehearsal strengthens transfer

3. STM has a limited capacity of roughly 7 items

What was Baddeley and Hitch’s (1974) critique?

STM is more complex and multi-component, not just a simple passive store

What did the participants have to do in Baddeley and Hitch (1974) effects of concurrent load research?

Participants had to perform two tasks simultaneously: a verbal reasoning task and a digit span task

Reasoning task- asked to verify sentences that describe two successive letters

Digital span task- remember list of random digits between 0-8 items long

What did Baddeley and Hitch (1974) find in this study and what does it imply?

Performance adversely affected by concurrent load. Implication that STM is not as central to complex tasks like reasoning as previously assumed

What are the components of working memory

1. Central Executive (integrates information, amodal)

2. Phonological Loop (verbal storage)

3. Visuo-spatial Sketchpad (visual and spatial storage)

What does the Central Executive do? (6)

1. Retrives information from LTM and allows subsequent manipulation

2. Integrates information from other WM components

3. Amodal- not tied to any specific modality

4. Constrained by available capacity- more demands placed on system less efficient

5. Regulates attention

6. Manages cognitive control

What does the Phonological Loop do?

Stores speech-based information; limited by time rather than fixed item number

What is the Visuo-Spatial Sketchpad for

Temporary storage and manipulation of visual and spatial information

What is the word length effect (Baddeley et al, 1975)

STM performance is better for shorter words- recall depends on how many items can be spoken in 2 seconds

Why do individuals like KF function relatively normal despite STM deficits?

Because complex tasks can rely on components other than the phonological loop

What does cognitive control refer to in the working memory model?

The ability of the central executive to manage conflicting demands