Capacity, Duration and Encoding:
Capacity: 7 Chunks +/- 2 Unlimited
Duration: 20 seconds Unlimited
Encoding: Acoustic & visual Semantic
Duration of STM:
Duration: Peterson and Peterson (1959) --> 24 students were asked to complete nonsence trigrams e.g WRT 303 (the idea was to remember this after prevention of rehursal was completed) The prevention was counting back in 3's from the number you started with, in this case 303. Each test lasted either 3,6,9,12,18,20.
Results: 90% had accurate recall at 3 seconds - this is because the duration of prevention of rehursal was minimal compared to the 2% that remember at either 18 or 20 seconds
Validity? - might not be valid because it lacks ecological validity as it can't be assossiated with a task that we may do in our lives. It is also a lab experiment and therefore people will act differently under pressure and may try to please the experimetor or vice versa - ruin the experiment
Bahrak et al (1975) - year book experiment - asked people to put names to faces - 48 years later able to recall more than 70% - more ecological validity.
Capacity of STM:
George Miller (1956) - magic number 7 + OR - 2 - How many chunks of information you could remember
Simon (1974) - suggested that the size of chunks mattered - e.g. trying to remember an 8 word phase is harder than trying to remember 8 sylballs
Cowan (2001) - suggested that it was atchually 4 chunks of information - suggesting that it wasn't as extensive as first thought
Vogel et al (2001) - thought that visual encoding in STM was limited to 4 chunks - showing that encoding was also though visual not just verbal in STM
Individual differences in STM capacity:
Josef Jacobs (1887) - used the digital span technique:
Remembering a list of numbers by looking at the first, covering it up, recalling it and then adding the second number to the list, repeating till you can't remember all of the digits in the list.
Results: Recall for digits = 9.3, whereas recall for letters = 7.3 - more likely to remember digits because there is less of them - leaving less room for variation
JJ also investigated whether capacity increased with age and found the digit span for 8 year olds is 6.6 whereas as for 19 year old it is 8.6 - suggesting his hypothesis is true. This could be due to increase in brain capacity and known use of memory stratagies
Semantic - though meaning
Acoustic - thorugh sounds
Baddely (1966) - looked at acoustic and semantic encoding in short and long term memory. Asked participants to recall words that were either acoustically or semantically similar or dissimilar.
Results: Easier to remember semantically similar in ST and acoustically similar in LT
Brandimote (1992) - if given a visual task when verbal rehursal was prevented (by saying lalala) participants were able to recall better in visual than in verbal where normally it would be translated to verbal information.
Atkinson and Shiffrin 1968
Sensory Memory: this is taken in through an environmental stimulus (what you see around you), you don't often notice you are looking at it and unless important is not transfered into STM memory
The duration of sensory memory is extrememly limited, less than a second.
Sperling (1960) - asked participants to look at either a grid of letters and numbers or a row for 50 milliseconds (a blink of an eye) and asked to recall what they could remember
Results: For the etire grid they were able to recall 5 items with 42% accuracy and at three items they were 75% accurate
This showed that sensory memory has a duration of approximitly 50 milliseconds and that the capacity of it is approximitly 5 items
Serial position effect:
Glanzer and Cuntiz (1966) - gave participants 20 words to remember (each shown individually)
Results: Able to remember the first few words (primacy effect) because they had been stored into LTM and the last few words (recency effect) because these are still in your short term capacity
Validity? - Labotory experiment and therefore lacks mundane realism.
The position of your memory in the body:
Your prefrontal lobes, at the front of your head store STM whereas your hypocampus stores LTM (this is located in the middle, bottom part of your head)
Weaknesses of MSM:
- It is very vague and doesn't go into detail about any of the stores
- Shows STM and LTM as unitary stores whereas later research has proved this not to be the case - EVIDENCE FOR THIS... KF suffered brain damage, could use visual representations and image images still but he was unable to verbally communicate
Spires et al (2001) - 147 patients with amnesia, their procedure and representation were ok but everything else wasn't. This shows that LTM is not a unitary store
Validity - all evidence here has eco-logical validity and was an observation study - this could mean the experienter sees what they want to see, however here it is clear that they are or aren't able to do something and therefore this is unlikely to happen.
Scatcher et al (2000) suggested that there were four LTM stores... Semantic memory - memory for knowledge about the world Eposidic memory - what you did yesterday or the film you watched last week Procedural memory - riding a bike or learning to read Perceptual - representaton system (PRS) - e.g. words that have been seen before you are able to identify even if not completely there e.g. D_N_CIN_ (Dancing)
Logie (1999) - STM relies on LTM and therefore cant come first - e.g. trying to remember a long list of letters, if they have meaning you need these meanings to help you remember them (the meanings come from LTM) e.g. BBCITVABCIBM
Ruchkin et al (2003) - asked participants to recall persuade words (made up words) + real words - easier to remember real words - used more parts of your brain showing that it was using LTM to remember the wirds
Positives of the MSM:
Simple structure - easy for anyone to follow and understand and gives people a basic idea of how the memory works
Clearly identifies that there are different stores of memory and how we use them
Studies have proved that this a reliable and more or less accurate diagram just simple