STM Flashcards
STM can be divided into separate stores depending on the material. Name them and describe them.
– VERBAL short term memory (much traditional research)
– VISUAL short term memory (more recent research)
– SPATIAL short term memory (split from an earlier visuo‐spatial store)
Rehearsal has a limited capacity of:
Earlier research overestimated the capacity limit due to chunking: Miller (1956): the magical number 7! Cowan (2000): the magical number 4!
Define a chunk.
Chunk = collection of concepts that have a strong association to one another and a much weaker association to other chunks concurrently in use.
What are the factors that can extend rehearsal capacity?
Probably best to think of the limit in terms of speaking time, with a capacity limit that can be extended a bit by chunking, easy links between items and a good natural rhythm.
Name and describe three pieces of evidence for the phonological nature of the phonological loop.
- Phonological similarity effect: if multiple items sound similar they are more confusable.
Baddeley (1966): Phonological similarity leads to poor immediate serial recall of five‐word sequences, whereas similarity of meaning has little (but significant) effect. - Word length effect: Long words take longer to rehearse and also produce lower memory spans [Baddeley, Thomson & Buchanan (1975)]. The effect corresponds to reading time.
- Articulatory suppression effect: preventing phonological rehearsal (e.g. by repeating a phrase such as “the the the” over and over) impairs verbal STM. A typical serial position curve for free recall of unrelated words: recency effect vanishes when recall is briefly delayed.
But: Articulatory suppression reduces the word length effect!
Does decay or rather interference better account for decline in STM performance when reharsal is prevented?
Keppel & Underwood (1962) looked at the data from Brown‐Peterson (1958/59) –> memory task: Present a triplet of letters on every trial (e.g. S F U), prevent reharsal for 3 or 18 seconds:
Proactive Interference (PI): earlier memories interfere with current memory (e.g. your old pin code interferes with your new pin code). Implications:
– Worse performance not (or hardly) due to decay of the current memory;
– Even memories of the previous trials were not gone (decayed)
see also release from PI experiment, evidence for the same thing
Delos Wickens (1976): release from PI. Remember three professions list - 12 sec of counting backwards. What happens?
- STM Memory loss occurs mainly through interference from information before (PI) (and after: RI), and not due to decay.
- Information in STM is not just phonological, but clustered according to semantic category (animals, fruits…), since different categories interfere less.
In VISUAL STM, what is a factor that heavily influences perfomance? Provide some evidence.
Complexity. As complexity increases visual STM content fades more quickly.
Phillips (1974) Recognition memory for random patterns as a function of complexity. Each pattern was followed by a test item comprising either an identical pattern or one which had a single square changed.
Luck and Vogel (2008) Change detection task: e.g. the green square has been changed to yellow. The probability of detecting a change declines with the number of squares to be remembered.
How many objects can be kept in visual STM, and how fast can they enter the store?
3 to 4 objects can be kept in visual STM and can be entered into visual STM at a rate of about 1 per 50 ms.
Name a test for spatial STM.
Corsi test of visuo‐spatial memory span: the experimenter taps a sequence of blocks and the participant seated opposite attempts to imitate. Numbers are there to help the experimenter.
Evidence for a division between visual and spatial STM?
Klauer and Zhao (2004): Primary spatial task (dot location) is disrupted by a secondary spatial task (movement), but not by a secondary visual task (color). Whereas a primary visual task (Chinese ideographs) is disrupted by a secondary visual task (color), but not by a secondary spatial task (movement).
