Short Term Memory (STM)
Capacity - 7 +/- 2 (7 plus or minus 2)
Jacobs - Used the digital span technieque to see how many numbers the participants (P's) could remember. (The size of the numbers increase by one each time e.g. 658, 7356, 25478, etc)
Duration - 20 - 30 seconds
Peterson and Peterson - Used trigrams to see how long the P's could remeber them for (by delaying the recall time). Repeated measures were used.
Encoding - Acoustically
Conrad - Gave the P's 6 consonnants (e.g DNBYWX) and found that letters that sounded disimilar were easier to remember (because they didnt get confused e.g B getting confused with V)
Long Term Memory (LTM)
Capacity - Unlimited
Duration - A life time
Bahrick et al - 392 students, split into 2 groups. Recall Group had to recall names from photos, while the Recognition Group had to match names to Photos. The recognition gorup was better.
Encoding - Mainly semantically
Baddeley - There are different types of LTM, some are 'Know hows' (e.g. knowing how to ride a bike) others remember smells, tastes, etc and others that make 'cognitive sense' (e.g. remembering a movies content but not the actual words).
Support for the MSM
Glanzer & Cunitz
- Looked into the primacy and recency effect.
- P's were shown 20 words and asked to recall the words.
- There were 2 groups. The Immedaite recall group and the Delayed recall group. (The delayed group was delayd by 30 seconds)
- The immediate recall group recalled the words from the begining from the list correct (which were rehearsed and passed to the LTM) and the last words (which were still in the STM).
- The delayed recall group only got the words at the end of the list right because they had been transferred to the LTM, while the words at the end were forgotten as they had decayed from the STM.
Working Memory Model (WMM)
The Centeral Executive deals with complex tasks (e.g. decision making). It also allocates tasks to the 'slave systems'. The centeral executive is also incharge of deciding which tasks are more important. It has a limited capacity, but can process information from the senses and is very flexible (since it can divert attention to more important tasks e.g. driving and not talking).
The two slave systems are the Phonological Loop and the Visuo-Spatial sketch (or scratch) pad.
The Phonological Loop has two parts to it.
Articulatory Control System controls verbal rehearsal and has time based capacity. It is also known as the "The Inner Voice"
The Phonological Store is speech based storage, with a decay rate of 2 seconds and is also known as "The Inner Ear"
The Visuo-Spatial Sketch/Scratch Pad deals with spatial and visuo information, it has a limited capacity and is also known as "The Inner Eye"
Research to support the MSM
Baddeley & Hitch
P's were given 6 digits to remember and were then told to do reasoning tasks. The P's were able to do both tasks successfully. If the two task required the same component, then the tasks would not be able to both be completed due to lack of capacity.
Case study of KF
After a accident he had visual and auditory problems, limited to verbal material (e.g letters and digits) but his knowledge of meaningful sounds (e.g. phone ringing) was intact. This show that the damage was restricted to the Phonological Loop.
Eye Witness Testimony (EWT) research
Loftus & Palmer
- A lab experiment
- Independant groups design (45 students, in 5 groups of 9)
- They watched a video of cars sliding on ice/snow into each other and were asked how fast the car was going when it ______. The verb was changed to see if the verbs effected memory. The verbs used were -
- Smashed participants guessed 41 mph
- Collided participants guessed 39 mph
- Bumped participants guessed 38 mph
- Hit participants guessed 34 mph
- Contacted participants guessed 32 mph
Loftus weopan focus
P's heard differnet types of arguments, one where a man walked out with a oily pen, another where there was a fierce argument and sound of breaking glass, then a man rush out with a blooded paper knife.
When asked to indentify the person the man holding a pen was correctly identified 49% while the man with the knife was correctly identifieds 33% of the time.
Loftus suggested the witness would focus on the weopan instead of the person.
Yuille & Cutshall found results that contridicted these findings. In a real life shooting the accuracy of recall remained the same, even after months. They were able to give details and were uneffected by leading qustions. Those who were the most distressed were the most accurate.
The accuracy of evidence given by children is greatly questioned, as children may not have developed correct schema's yet and are easily influenced by things like leading questions.
Adults evidence may also be questionable, as prior knowledge may effect their memory (e.g. steiortypes people). Accuracy also drops over time.
Kent & Yuille
Found children are more likely to identify people who they had interactions with two days ago from a list of photos. However, if the person wasn't shown the child still picked a picture, as they felt like they had to choose one to please the adults.