working model of memory

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Cognitive Psychology The working Model of Memory By Baddeley and Hitch (1974)

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Working Model of Memory

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Cognitive Psychology

The working Model of MemoryBy Baddeley and Hitch (1974)

Learning objectives• Understand what is meant by the

concept of working memory.• Describe the working memory model

and understand the functions and limitations of its components.

• Describe and evaluate the evidence on which the working model is based.

• Understand the strengths and weaknesses of the model.

Background to the WMM• Baddeley and Hitch (1974)

believed that there was more to STM than in the multi-store model (i.e. more than just being one store house).

The components of the WMM

• A complex and flexible system with different components

A MORE ACTIVE MODEL OF MEMORY

3 main components• The central executive (supervisor)• Has overall control• Limited capacity• Can process information from any

sensory modality

Central Executive• Responsible for a range of control

processes e.g. • setting task goals, • monitoring and correcting errors, • starting rehearsal process, • switching attention between tasks,• inhibiting irrelevant information• Retrieving information from LTM• Coordinating activity needed to carry

out more than one process at a time.

Two slave systems• The slaves to the CE can be used

as storage systems• Which frees up some of the CE’s

capacity to deal with more demanding information processing tasks.

• The slave systems have separate responsibilities and work independently of one another.

1. Phonological Loop• (the inner voice)

has limited capacity

• A temporary storage system for verbal information in a speech-based form.

2. The visuo-spatial sketchpad• The inner eye• Limited capacity• Temporary

memory system for holding visual and /or spatial information

Revised model (1999)• Phonological loop now = passive

storage system called• Phonological store which is linked to a

rehearsal system called• The Articulatory Loop• Maintained by subvocal repetition.• The visuo-spatial sketchpad = passive

visual store called• Visual cache (collection of data) which is

linked to an active ‘inner scribe’ that acts as a rehearsal mechanism.

The dual task method• To test the function of STM,

Baddeley and Hitch asked participants to perform:

• A reasoning task (sentence-checking)

• While reciting a list of 6 digits.• According to the multi-store model

the capacity of the STM would be taken up with the digit task.

Recite the six digit number 482917 aloud while ticking True or False

• 1. B is followed by A BA• 2. A is preceded by B AB• 3. A is not followed by B BA• 4. B follows A AB• 5. B does not follow A BA• 6. B is not followed by A AB• 7. A follows B AB• 8. B is not preceded by A AB• 9. A is not followed by B BA• 10. B does not precede A AB

Findings• Participants made very few errors

on either task (although the speed of sentence checking was slightly slower than when done on its own).

Conclusions• Baddeley and Hitch concluded that

STM must have more than one component and

• Must be involved in processes other than simple storage, e.g. reasoning, understanding and learning.

• STM is a kind of workspace where a variety of operations can be carried out on both old and new memories.

A MORE ACTIVE MODEL OF MEMORY

Very important• Two tasks can be carried out at

the same time as long as• They are being carried out by

different modalities (parts of the memory system).

• LTM is a more passive store for previously learned material.

• The ACTION is in the STM.

Evidence for the phonological loop• Baddeley et al. (1975)

• Visual presentations of word lists for a brief time

• Participants asked to write them down in serial order.

• Condition 1 – lists consisted of 5 words familiar, one-syllable English words, e.g. harm, wit, twice.

• Condition 2 – 5 words, polysyllabic, e.g. organisation, university, association.

findings• More short words were recalled• This was called ‘the word length

effect’• Conclusion• Capacity of the loop is determined by

the length of time it takes to say a word rather than by the number of items.

• The estimated time was 1.5 seconds

Method • Laboratory experiment using a

repeated measures design • Evaluation• Well controlled• Longer words may be less familiar

than short words. This could have affected the recall rather than the length.

• No ethical issues if fully informed consent obtained.

The word length effect under articulatory suppression

• Participants were given a task that would usually make use of the articulatory loop

• Asked to repeat a meaningless chant aloud e.g. la-la-la

• The word length effect disappeared and recall for short words was no better.

• This suggests that a verbal rehearsal system is important and when suppressed, processing has to take place elsewhere (maybe the central executive)

Evidence for the visuo-spatial sketchpad

• The visual store also has limited capacity.

• Shepard and Feng (1972) asked participants to imagine folding flat shapes in order to make a cube.

• They had to decide whether the arrows would meet head on.

findings• The time taken to make the decision

was related to the number of folds they would have had to make if they had actually been doing the task.

• Visual images work in a similar way to real life perception.

• People are likely to find it difficult to do two tasks simultaneously if they both use the visuo-spatial sketchpad.

Research: Baddeley et al. 1973Participants were given a

tracking task (following a spot of light with a pointer around a circular path while imagining block capitals such as H, T, F

and E.

• Participants were asked to start at the bottom left-hand corner, to respond to each angle with a ‘yes’ if it included the bottom or top line of the letter and a ‘no’ if it did not.

F H

findings• Participants had enormous difficulty

in tracking the spot of light and accurately classifying the corners.

• The two tasks were competing for the same limited resources of the visuo-spatial sketchpad.

• This is supported by the fact that participants could carry out the tracking task while performing a verbal task.

Logie (1995)• Suggested that the visual cache

stores information about visual form and colour

• The inner scribe processes spatial and movement information.

Klauer and Zhao (2004) supported this

• Participants carried out one of two tasks:A visual taskA spatial task

• At the same time they were asked to do either

• A spatial interference task• A visual interference task• No secondary task (control condition)

findings• Performance of the spatial task was

much poorer for those carrying out a spatial distractor task at the same time compared with those doing the visual distractor task and vice versa.

• PET scans show evidence for separate systems. Brain activity differs.

• More activity in the left half for visual • More activity in the right half for

spatial

Evidence for central executive• Critical role in attention, planning

and coordination.• Most flexible component of the

working memory.• More difficult to find evidence for.• Easier to study the slave systems.• Research on the CE tends to focus

on the different functions.

Baddeley (1996)• Investigated the functions of the

CE in selective attention and switching retrieval plans.

• Participants were asked to generate random strings of digits by pressing numbered keys on a keyboard.

Try this (if you have a computer)• Think of a sequence of eight digits

that show no systematic pattern (Note that patterns easily emerge so this is difficult).

• At the same time:• Recite the alphabet• Count from 1• Alternate between letters and

numbers (A1B2C3D4E5F6 etc)

findings• Baddeley found that the generated digit

string became considerably less random in Condition 3 when particpants were switching from alphabet to numbers at the same time.

• Baddeley concluded that both the random number generation task and the alternation task were competing for the same central executive resources.

Evaluation of the working memory model

• A very influential model• Accepted by cognitive psychologists in

preference to the idea of a STM store.• More plausible than the multi-store model

because it explains the STM in terms of active process rather than passive storage alone.

• Verbal rehearsal is accepted as one optional process within the articulatory loop rather than the only way to transfer information to the LTM.

More positives of the WMM• It can account for some of the

findings that the MSM finds difficult to explain.

• Research support comes from dual-task studies although

• KF could remember visual but not verbal stimuli in STM – supports the idea of at least 2 separate systems in the STM.

• Brain scans show different areas of the brain are used for visual and verbal tasks which supports the WMM.

• The role of the CE is not fully understood and it is likely to be comprised of more than one component.

• Fails to account for musical memory as we are able to listen to instrumental music without impairing performance on other acoustic tasks.