The Working Memory Model
Baddeley and Hitch (1974) - Short term memory research 'what is it for?' Multi-store Model argued STM was unitary store. Baddeley and Hitch referred to the case of KF who had a digit span of 2 but could still transfer new information into his long term memory to prove this wasn't the case.
To test that there is more than one component in the STM Baddeley and Hitch devised the dual task method. This is where participants are asked to carry out a primary task whilst also engaging in a secondary task. Performance is compared to performance on each of the tasks when done individually.
Conclusion that two tasks can be carried out in the STM simultaneously. LTM was seen to be a more passive store.
The components of the working memory Model
According to Baddeley and Hitch there are three main components:
- Central executive has overall control. It has limited capacity. Can process information from any sensory system. Responsibility for goal setting and starting the rehearsal process. It is supported by storage systems.
- Phonological loop a limited-capacity, temporary storage system for holding visual and spatual information.
- Visuo-spatial sketchpad a limited-capacity, temporary memory system for holding visual and spatial information.
Evidence for the phonological loop
Baddeley, Thomson and Buchanan (1975)
Researchers gave visual presentations of word lists for very brief exposures and asked participants (pp's) to write them down in serial order.
One condition the lists consisted of 5 words taken from one syllable English words such as halm, wit, twice.
Second condition 5 words came from polysyllabic words e.g. organisation and university. Better recollection was found in the short words.
This is called the 'word length effect'.
Conclusion: the capacity of the loop is determined by length of time it takes to say words rather than number of items.
Methodological issues: laboratory experiement using repeated measurements.
Ethical issues: informed consent and debriefing is always necessary.
Evidence for visuo-spatial sketchpad
Baddeley, Grant, Wight and Thomson (1973)
Participants were given a simple tracking task while carrying out a simultaneous visual imagery task.
The two tasks were competing for the same limited resources of the visuo-spatial sketchpad. This is supported by the finding that participants could successfully carry out the tracking task at the same time as performing a verbal task.
Methodological issues: highly controlled laboratory experiment although the task was artificial. They used repeated measures to eliminate effects of individual differences.
Ethical issues: consent from participants was necessary as well as debriefing afterwards. Participants may have felt frustrated at being unable to complete both tasks effectively and it is important they were given reassurance that this is normal.