Evidence for the Working Memory Model. From lab experiments From case studies From brain scanning

Ethics You will be taking part in a number of short experiments on working memory Please note You have the right to withdraw at any point You will not be harmed during the experiment Please write any answers down on the answer sheet and do not put your name on it. Any questions?

To test the idea of more than one component in STM , Baddeley and Hitch devised the dual task technique. The following is one example of this ….. Ppts were asked to perform a ‘reasoning task’ whilst simultaneously reciting aloud a list of 6 digits.

482917 Your turn! Answer - true B is preceded by A A B True/False A follows B A B True/False Answer -False Repeat the numbers below aloud, whilst ticking the true/false answers on the sheet in front of you 482917

1: B is followed by A BA True/False 2: A is preceded by B AB True/False 3: A is not followed by B BA True/False 4: B follows A AB True/False 5: B does not follow A BA True/False 6: B is not followed by A AB True/False 7: A follows B AB True/False 8: B is not preceded by A AB True/False 9: A is not followed by B BA True/False 10: B does not precede A AB True/False

Although it takes longer this task is possible to do 1: B is followed by A BA True/False 2: A is preceded by B AB True/False 3: A is not followed by B BA True/False 4: B follows A AB True/False 5: B does not follow A BA True/False 6: B is not followed by A AB True/False 7: A follows B AB True/False 8: B is not preceded by A AB True/False 9: A is not followed by B BA True/False 10: B does not precede A AB True/False Although it takes longer this task is possible to do

Baddeley & Hitch (1975-6)….. So they asked participants to perform a reasoning task whilst simultaneously reciting aloud a list of 6 digits. If the MSM is correct and STM is a unitary store, then participants would be expected to show impaired performance on the reasoning task because their STM would be fully occupied. However, Baddeley & Hitch found Participants made few errors, although the speed was slightly slower.

What does this tell us about STM? Clearly STM is more than a unitary store with limited capacity and limited duration. It is more complex than the MSM suggests

The results of their research lead Baddeley to conclude that STM could not be a single and entirely separate store – it was clearly made up of different parts The next thing he needed to do was to find evidence for the different components of working memory

Aim: to find evidence for the central executive To do this Baddeley (1996) investigated selective attention. Procedure: He asked participants to generate random strings of digits on a keyboard (this is quite hard as you have to pay close attention in order to avoid some kind of pattern emerging). Cond 1 The primary task of generating random strings of digits was carried out alone Cond 2 The primary task was carried out alongside another task such as reciting the alphabet or counting from one Cond 3 The primary task was carried out alongside alternating between letters and numbers (A1, B2, C3) Result: The generated digit string became increasingly less random in Condition 3 where participants had to switch from alphabet to numbers at the same time. Conclusion: Baddeley concluded that both the random number generation task and the alternation task were competing for the same central executive resources which is why ppts were unable to do the task successfully

More evidence for Central Executive fMRI scans Bunge et al (2000) found that when Ppts were doing a dual-task, fMRI scans showed significantly more activation This shows that the increased attentional demands of the two simultaneous tasks increased brain activity This provides support for the proposed role of the central executive as the aspect which directs attention and allocates resources

Evidence for the phonological loop and articulatory process Experiment coming up….. Remember the following words which you will then be asked to write down

Twice

Harm

Calm

Share

Tree

Book

Sun

Four

Key

Short

Did you recall all 10 of them? Harm Twice Calm Share Tree Book Sun Four Key Short

And again..recall these:

Association

Representative

Discouragement

Meaningfulness

Suppression

Enhancing

Component

Performances

Forgetting

Damaging

Recall them! How many did you get right? Association Representative Discouragement Meaningfulness Suppression Enhancing Component Performances Forgetting Damaging This experiment supports the existence of the phonological loop. The word-length effect occurs – because people cope better with short words than long words in working memory as the memory trace doesn't last very long and so long words are quickly forgotten

Word- length effect It seems that the phonological loop only holds the amount of information that you can say in 1.5 - 2 seconds (short duration) This makes it hard to remember a list of long words such as ‘association’ and ‘representative’ compared to shorter words like ‘harm’ and ‘twice’

But….. The word length effect disappears if a person is given an articulatory suppression task (like saying ‘the, the, the’ while reading the words). The repetitive task ties up the articulatory process which means you can’t rehearse the shorter words any more quickly than the longer ones, therefore the word length effect disappears.

Evidence for the visuo-spatial sketchpad Participants were given a visual tracing task (they had to track a moving light with a pointer). At the same time they were given one of two other tasks Task 1 was to describe all the angles on the letter F Task 2 was to perform a verbal task. PPts found Task 1 very difficult, PPts found Task 2 was easy because the second task involved two different slave systems. This was controlled laboratory experiment using a repeated measures design to eliminate individual differences. However the task was artificial. F

Logie (1995) suggested that the visual cache stores information about visual form and colour and the inner scribe processes spatial and movement information.

PET SCAN Evidence Studies using positron emission tomography (PET) scans have also provided evidence for separate spatial and visual systems. There appears to be more activity in the left half of the brain of people carrying out visual working memory tasks but more in the right half of the brain during spatial task.

Evidence for the episodic buffer Baddeley et al (1987) PPTs were shown words and then immediately asked to recall them He found that recall was much better for sentences than unrelated words This Supports the idea of a ‘general’ memory store that draws on LTM (knowledge/semantics/meaning)

Further evidence comes form case studies KF for example (Shallice & Warrington 1970) – whose auditory digit span was only 2 – clearly his STM was damaged, but he could still transfer information to LTM. His visual memory was unaffected though. He could remember a list of digits presented visually. This suggests there must be several different components to STM.

Other case studies include .. SC – who had generally good learning abilities with the exception of being unable to learn word pairs that were presented out loud. This suggests damage to the phonological loop LH - had been involved in a road accident. He performed better on spatial tasks than those involving visual imagery. This suggests separate visual and spatial systems. For more information on case studies see the additional power point on your blog