Studied by 1 person
STM - duration, capacity, encoding
Duration - 18-30 seconds
Capacity - 5-9 bits
Encoding - Acoustically
LTM - duration, capacity, encoding
Duration - Unlimited
Capacity - Unlimited
Encoding - Semantically
Sensory Registers - duration, capacity, encoding
Duration - 1/4 second
Capacity - V. large
Encoding - Five senses
Jacobs (1887)
Aim – To investigate the capacity of STM
Procedure - Participants are made to recall a series of letters or numbers in serial order and to recall immediately after. They increase the digits each time.
Findings - It was found on average participants remembered 9 numbers and 7 letters.
Conclusion - STM has a capacity of 5-9 bits.
Jacobs (1887) A03
High control, more valid
Low mundane realism, less generalisable
Low ecological validity, less generalisable
Pioneering, useful
Reliable, increases validity
Peterson & Peterson (1959)
Aim – To investigate the duration of STM
Procedure – Participants are given a trigram to remember then had to count back in 3s from a random number to prevent rehearsal. They has to recall the trigram after a certain amount of time (3s,9s etc).
Findings – After 3 seconds, 80% of trigrams were recalled. There was 50% recall after 6 seconds and less than 10% after 18 seconds.
Conclusion - STM has a duration of 18-30 secs.
Peterson & Peterson A03
High control, high internal validity
Low mundane realism, low external validity
Low ecological validity, low external validity
Reliable, increases validity
Bahrick (1975)
Aim – To investigate duration of LTM
Procedure – He asked participants, aged 17-74, to recall classmates using free recall, photo recognition, name recognition and name and photo matching.
Findings - After 34 years recall was 90% and after 48 it was 80%.
Conclusion - Duration of LTM is unlimited.
Bahrick A03
High mundane realism, high external validity
Low control, decreases internal validity
Pioneering, useful
Type of information, questionable
Baddeley (1966)
Aim – To investigate how memory is encoded
Procedure – Participants are given four sets of words (acoustically similar, acoustically dissimilar, semantically similar, semantically dissimilar) and asked to immediately recall them. Then they had to recall after 20 seconds.
Findings - More mistakes were made on acoustic words when using STM. Whilst using LTM, participants confused more semantic words.
Conclusion - STM encodes acoustically and LTM encodes semantically.
Baddeley A03
High control, high internal validity
Low mundane realism, low external validity
Low ecological validity, low external validity
Volunteer bias, not representative
Multi store Model
The multi store model begins with processing information from our surroundings. When information is detected by the five senses it is sent to the sensory registers which has a duration of ¼ of a second, but it has a large capacity. There are two main stores in the sensory register: iconic and echoic memory. If attention is paid, the information enters the short-term memory which has a capacity of 5-9 bits and is encoded acoustically. Information is lost after 18-30 seconds unless maintenance rehearsal is carried out and the information is able to be retrieved. If prolonged rehearsal is carried out, the information is passed to LTM which has unlimited capacity and duration and encoded semantically. LTM is able to retrieve information from the STM when it is needed.
MSM A03
Pioneering, useful
Supporting research, valid model
Doesn’t account for flashbulb memories, limited in explaining memory store features
Contradictory evidence, too simplistic
Prolonged rehearsal isn’t needed, too simplistic
Case Studies - KF, HM, CW
KF had brain damage from motorcycle accident. He had no issue with LTM, but his STM was only 2 bits and he forgot auditory stimuli more than visual stimuli.
HM had brain surgery to cure epilepsy where his hippocampus was removed. He lost the ability to create new memories (anterograde amnesia). This showed he damaged his LTM, but his STM was still intact.
Clive Wearing had an infection that spread to his brain. He damaged his STM and parts of LTM. CW was able to recall how to play a piano but not his wedding day.
Working Memory Model
The Working Model Memory (WMM) was created by Baddeley and Hitch in response to criticism of the Multi Store Model of single unitary stores. People believed the STM had different parts, so the WMM showcases the STM. The model suggests that the working memory is an active store as it contains information that is currently thought about. When attention is paid to information, the information passes to the Central Executive, which holds overall control of the STM. The Central Executive is multi-modal as it deals with both stimuli but has a very limited capacity, so it passes information to one of two slave stores: Phonological Loop and Visuo-Spatial Sketchpad. Visual and Spatial information passes to the Visuo-Spatial Sketchpad which has two sub-stores. The visual cache stores visual information e.g., shape and colour. The second sub store, Inner Scribe, deals with the spatial relationship between objects e.g. distance. The Phonological Loop holds auditory information and passes it to its sub stores. The articulatory control system carries out maintenance rehearsal rehearsing the words in a loop for two seconds. The phonological store contains words you hear. In the 2000s, the Episodic Buffer was added to the WMM. The Central Executive and the Episodic Buffer pass each other information that the Episodic Buffer combines to make episodes/memories. This links to the Long-Term Memory.
WMM A03
Supporting evidence from KF, valid model
Support evidence from Dual Task Method, valid model
Supporting evidence from PET scans, valid model
Pioneering model, useful model
Very little is known about the Central Executive, model is too simplistic
Doesn’t account for musical memory, reduces validity
Suggests spatial and visual information are linked to the VSS, too simplistic
Types of LTM - Episodic Memory
Ability to recall personal events (episodes) from our lives. These memories are complex and time-stamped, involving a conscious effort to recall the memories. Lots of information interwoven to produce a single memory.
Types of LTM - Procedural Memory
How to do things. These memories aren’t usually time stamped and we don’t have to consciously recall it.
Types of LTM - Semantic Memory
Shared knowledge of the world. These memories aren’t time stamped but we must consciously recall it. It is constantly being added to.
LTM Stores A03
Clive Wearing support, valid theory
Lack of variable control, findings are less valid
Brain scans aren’t reliable, less valid
Real life application, more useful
Interference
When one memory blocks another, causing one or both memories to be disrupted or forgotten.
Proactive Interference
When old memories disrupt the recall of new memories, causing new memories to be forgotten.
Retroactive Interference
When new memories disrupt the recall of old memories, causing old memories to be forgotten.
Interference Support - McGeoch and McDonald
Participants are made to learn a new list of words after being able to 100% accurately recall the first list. The new list ranged in similarity to the first list and then they had to recall the original list.
The more similar the words were to the original list, the worst the recall of the original list was. This shows us that interference causes more forgetting when words are similar.
McGeoch & McDonald A03
Lab support, more valid
high control, more valid
Lacks ecological validity, less generalisable
Retrieval Failure
When the lack of cues means memory is available but not accessible.
Context-dependent forgetting
When memory is forgotten due to the lack of external cues e.g. environment
State-dependent forgetting
When memory is forgotten due to the lack of internal cues e.g. emotions
Encoding Specificity Principle
A helpful cue must be present at encoding and present at retrieval. If cues at encoding and retrieval are different, there will be some forgetting.
EWT - Misleading Information - Gabbert et al. (2003)
Aim: To investigate the effect of post event discussion on the accuracy of eyewitness testimony.
Procedure: 60 university students and 60 older adults watched a video of a girl stealing money from a wallet. They were either tested individually (control group) or in pairs (co-witness group). The pairs watched different videos but were told they’d watched the same one – one had actually watched the girl stealing. The pairs discussed the crime together. All participants completed a questionnaire on the event.
Findings: They found 71% of the witnesses in the co-witness group recalled information they hadn’t seen and 60% said the girl was guilty when they hadn’t seen her commit a crime.
Conclusion: Post-event discussions can change eye-witness testimonies.
EWT - Misleading Information - Loftus and Palmer
Aim – To investigate the effect of leading questions as misleading information on EWT.
Procedure – 45 students were shown 7 videos of a traffic accident, followed by a series of questions about “how fast were the cars going when they {smashed, collided, bumped, hit or contacted} each other?” The IV was the verb used and DV was the speed reported.
Findings – The more severe verbs resulted in higher speed estimations. Smashed had the highest speed of 40.8mph and contacted had the lowest speed of 31.8mph.
Conclusion – The harsher the verb used the higher the speed estimated, showing the leading question reduced the accuracy of EWT.
EWT - Anxiety - Johnson and Scott (1976)
Aim – To investigate if anxiety affects the accuracy of eyewitness testimony and facial recognition
Procedure – Participants sat in a reception area of a laboratory. The receptionist left the participants alone. They experienced one of two conditions:
1. ‘No weapon’ condition – They overheard a conversation about equipment failure then an individual (target) left the lab and walked past the participant holding a pen, hands covered in grease.
2. ‘Weapon’ condition – They overheard a heated exchange and the sound of breaking glass and crashing chairs, followed by the target running into the reception area, holding a bloodied letter opener.
They were then shown 50 photographs and asked to identify the target.
Findings – Those who saw the man holding a pen correctly identified the man 49% of the time and those who saw the man holding a knife correctly identified the man 33% of the time.
Conclusion – Those in the ‘weapon’ condition had higher anxiety so had lower accuracy.
EWT - Anxiety - Yuille and Cutshall (1986)
Aim – To investigate the effect of anxiety in a real life shooting.
Procedure – They interviewed 13 out of 21 witnesses, aged between 15 and 32, that the police originally interviewed, 4-5 months later.
Findings - They found those who took part in the follow up interview were accurate in their eye witness testimonies five months later. All of the major details stayed the same but minor details changed e.g. estimates of age, height and weight. The witnesses avoided leading questions and anxiety experienced at the time of the event had little or no effect on their memory of the event.
Conclusion – In real life cases of extreme anxiety, the accuracy of eyewitness testimony is not affected.
Cognitive Interview Techniques
Recall Everything – Witness recalls every single thing, no matter how minor they think the details are.
Context Reinstatement – Witnesses are asked to put themselves back into the environment in hopes of triggering a cue.
Recall in Reverse Order - Witnesses start from a point of the event and go backwards in time.
Change in Perspective – Witnesses recall from another witnesses point of view.
Note
Flashcard