short term and working memory Flashcards
(24 cards)
What is the definition of short-term memory (STM) according to the Atkinson and Shiffrin model?
STM is our conscious representation of ‘the present moment’. It is a temporary store in which we integrate current sensory experience with long-term memory to achieve current goals.
What is the typical capacity of STM in the Atkinson and Shiffrin model?
STM has a limited capacity of approximately 7 ± 2 items.
What is the duration of STM in the Atkinson and Shiffrin model?
STM typically lasts for about 15–30 seconds.
What are the sources of information in STM?
Information in STM comes from sensory registers and from retrieval of information stored in long-term memory (LTM).
What is maintenance rehearsal and how is it used in STM?
Maintenance rehearsal involves using an ‘inner voice’ — a language-based auditory code — to mentally rehearse information. This keeps the information active in STM and helps transfer it to LTM.
How does maintenance rehearsal contribute to the transfer of information to LTM?
Rehearsal maintains the information in STM and strengthens its memory trace, facilitating its storage in LTM.
What evidence supports the role of rehearsal in transferring information to LTM?
The primacy effect — better recall of early list items — shows that items rehearsed more often are more likely to be transferred to LTM.
What task is commonly used to measure the capacity of STM, and how does it work?
The digit-span task is used, where participants are asked to immediately recall sequences of verbally presented digits. The length of the sequence is increased until the person fails to recall correctly. The average adult span is 7 ± 2 items.
What task is used to measure the duration of STM and how does it work?
The Brown-Peterson task is used. Participants are shown 3 consonants (e.g., “D-P-R”) and must recall them after a filled retention interval, such as counting backward by 3s, to prevent rehearsal.
What are the findings of the Brown-Peterson task regarding STM duration?
Recall drops to 50% at 3 seconds, 20% at 9 seconds, and near 0% after 12–18 seconds, showing rapid decay without rehearsal.
What is the primacy effect and how does it support the existence of LTM?
The primacy effect is the better recall of early list items, which is believed to result from increased rehearsal and transfer into LTM.
What is the recency effect and how does it support the role of STM?
The recency effect is the better recall of the most recent items on a list, which are still active in STM.
Why are middle list items harder to recall?
Middle items are often not rehearsed enough for LTM storage and fade from STM before recall, making them least likely to be remembered.
What experimental evidence supports the existence of separate STM and LTM stores?
The recency effect disappears when a filled retention interval disrupts STM. The primacy effect is eliminated when rehearsal is prevented with a concurrent task. These findings suggest different mechanisms and stores.
Q15: What did Craik & Tulving’s (1975) experiment investigate?
They investigated how different types of processing affect memory encoding and recall by having participants encode words at different levels.
What were the three types of processing in Craik & Tulving’s experiment?
Shallow (visual): “Is this word in uppercase?”
Intermediate (phonetic): “Does this word rhyme with X?”
Deep (semantic): “Does this word fit the sentence ‘The X ate the grass’?”
What were the results of the levels of processing experiment?
Semantic (deep) encoding led to the best recall, while shallow processing led to the poorest recall.
How did the findings challenge the original STM model?
The results suggest that STM is not just a passive maintenance system; it also supports meaningful encoding, challenging the idea that only rehearsal transfers information to LTM.
What is the phonological loop and what is its function?
The phonological loop holds and manipulates auditory-verbal information, such as in digit-span backward tasks. It relies on a left-hemisphere fronto-temporal neural network
What is the visuo-spatial sketchpad and what is its function?
It stores and manipulates visual-spatial information, like mental rotation or Corsi block-tapping. Its neural basis lies in the right occipital-parietal network.
What is the central executive and what does it do?
The central executive is responsible for attention control, planning, and task-switching (e.g., in problem-solving). It operates through the prefrontal cortex, including the dorsolateral PFC and anterior cingulate.
What is the episodic buffer and its role in cognition?
The episodic buffer integrates multi-modal information (e.g., scenes, episodes) into a unified representation for conscious awareness. It is associated with the parietal cortex (association area).
How did Baddeley’s model shift the understanding of STM?
It replaced the idea of a single STM store with a multi-component system (phonological loop, visuo-spatial sketchpad, episodic buffer, and central executive) that supports active, goal-directed reasoning and processing.
What are the neural correlates of each component in Baddeley’s model?
Phonological Loop: Left fronto-temporal network
Visuo-Spatial Sketchpad: Right occipital-parietal network
Central Executive: Prefrontal cortex
Episodic Buffer: Parietal cortex
