Phonological Loop model (Working Memory)

Phonological Loop model (Working Memory)

1. developmental & cross-linguistic differences

   • developmental differences
     • faster rehearsal means better recall (more rehearsal per per 2sc)
     • developmental growth of memory span, Dempsey (1981)
     • as children's rate of speech increases so does their recall span, Nicholas (1981)
   • cross-linguistic differences
     • differences with mean digit span correlates with differences in how long it takes to say them
       • NOTE: these are correlations not causal relations
   • younger children have poorer recall performance on longer spoken words compared to same stimuli presented as images
     • older children (7yo) show word-length effect in both modalities, Hitch et al. (1988)

2. Irrelevant speech effect

   • Salamé and Baddeley (1982) ignoring irrelevant speech was more interfering than other irrelevant noise
     • demonstrates unattended speech enters phonological store (Blocking subvocalised word stimuli) BUT other noises don't
     • Suppression eliminates the irrelevant speech effect (possibly by blocking word encoding)
   • Macken & Jones (1995) contradictory evidence that unattended non-speech (tones) can cause the same disruptive effect
     • possibly due to broader memory mechanisms rather than phonological loop
   • possible both theories correct in different situations

3. neurological study

   • Vallar & Baddeley (1984) - studied P.V. who showed selective verbal memory deficit
     • Left parietal lesion from stroke- only left with 2 digit auditory span yet fluent and normal rate of speech
       • Poor recall with phonemically similar words- possible phonological store damage? Had no word length effect- also support phonological store damage theory
         • subvocal rehearsal wouldn't help recall shorter words rather than long words
       • better memory span with visual words than spoken
         • showed no phonemic similarity or word length effect
           • possibly compensating for phonological loop damage by using her visio-spatial scratchpad more
     • this is an example of dissociation suggesting storage and rehearsal are separate
   • Paulesu et al. (1993)- used PET scans for 3 tasks
     • task assumptions- phonological loop associated with Broca's area and supramarginal gyrus. rehearsal associated with Broca's area. phonological store associated with supramarginal gyrus. if these assumptions are correct!

4. theoretical issues

   • it doesn't explain irrelevant speech effect
   • Lovatt et al. (2000)- challenged word length effect. claimed word complexity was responsible. word length effect could be eliminated if complexity was the same.
   • Hulme et al. (1984)- challenged rehearsal is affected by word length. example: 4yo not developed rehearsal ability showed word length effect.
   • Cowan et al. (1992)- demonstrated word length effect caused by output delays (doesn't affect rehearsal)
   • Baddeley (2000) - suggested a 4th component- the episodic buffer.
     • explains that articulatory suppression which 'should' eliminate recall by occupying all resources (rehearsal/subvocalisation), thereby preventing visual stimuli registering in the phonological loop, has only a weak effect.
     • evidence shows visual similarity of word stimuli affect span. suggesting visual and phonological info are bound. therefore, a separate system involved.
     • very amnesic patients (damaged episodic LTM) can keep current info in mind (not learned). eg. Tulving recorded a patient could remember the objective in a game of bridge, the cards played and the score across a series of games. suggesting if STM & LTM not linked there must be another store.
   • addressing the issues:
     • create a new model from scratch
     • revise the model addressing its deficiencies
     • use computational modelling to create alternative models.

5. phonological store

   • stores small amount of what's seen/heard

6. subvocalisatino process

   • speech automatic access to loop. visual stimuli needs recoding

7. Phonological working memory, Baddeley (1975)

   • articulatory suppression, Baddeley (1984)
     • secondary task involving repetition of irrelevant words
       • word-length effect
     • memory span reduced
     • word length effect reduced in both modalities
     • phonemic similarity effect reduced in visual stimuli
     • eliminates word-length effect for both modality
     • only eliminates phonemic similarity effect in visual stimuli
   • phonemic similarity effect
     • more difficult to remember similar sounding words