memory Flashcards
What is short term memory (STM)?
memory for immediate events. Has a short duration - disappears unless rehearsed. Also has a limited capacity and tends to be coded acoustically.
What is long term memory (LTM)?
memory for events that have happened in the past. Has a potentially unlimited duration and capacity and tends to be coded semantically.
What is capacity?
a measure of how much can be held in memory.
How did George Miller assess the capacity of STM?
reviewed psychological research in an article called ‘The magic number 7 +/- 2’ and concluded the span of immediate memory is about 7 items
Evaluate research into STM capacity
One criticism of the research investigating STM is that Miller’s original findings cannot be replicated.
Cowan reviewed a variety of studies on the capacity of STM and concluded that STM is likely to be limited to about 4 chunks.
What is duration?
How long information can be held in memory
How was the duration of STM assessed? Lloyd and Margaret Peterson)
used 24 students
each tested over 8 trials
on each trial they were given a consonant syllable and a 3-digit number (e.g. THX 512)
they were asked to recall the consonant syllable after a retention interval of 3,6,9,12,15,or18 seconds
during the interval they had to count backwards from their 3-digit number
on average, 90% were correct over 3 secs, 20% after 9 secs, and only 2% after 18 secs.
this suggests STM has a very short duration - less than 18 secs- as long as verbal rehearsal is prevented
Evaluate the research into STM duration
Another criticism of research investigating STM is that is that it relies on performing artificial tasks. Trying to remember random numbers and letters does not truly reflect most everyday activities where what we are trying to remember is meaningful
However, we do sometimes try to remember fairly meaningless things, such as postcodes and phone numbers
this means that, although the task was artificial, the study does have some relevance to everyday life.
What is coding?
the way information is changed so that it can be stored in memory. Information enters the brain via senses. It is then stored in various forms, such as visual codes (pictures), acoustic codes (sounds) or semantic codes (meanings/experiences)
How was semantic and acoustic coding assessed in STM and LTM (Alan Baddeley)?
Alan Baddeley used words lists of words that are semantically similar but acoustically dissimilar, and words that are acoustically similar but semantically dissimilar, to test the effects of acoustic and semantic similarity on STM/LTM. He found participants had difficulty remembering acoustically similar words in STM, but not in LTM, whereas semantically similar words posed little problem in STM but led to muddled STM’s.
This suggests that STM is largely encoded acoustically whereas LTM is largely encoded semantically
Evaluate research into coding in memory
Some experiments have shown that visual codes are also used in STM
-Brandimote (1992) found that people used visual coding in STM if they were given a visual task (pictures) and prevented from doing any verbal rehearsal before performing a visual recall task. We normally translate visual images into verbal codes in STM but as verbal rehearsal was prevented, participants used visual codes. This suggests that STM is not exclusively acoustic.
What is the multi-store model of memory?
A theory proposed by Atkinson and Shiffrin to show how memory works. There is 3 separate memory stores (sensory, short term, and long term) and these are linked by the processes that enable information to transfer from one store to the other
Explain all of the stages of the multi-store model of memory
-Information is held at each of the senses in the sensory register. This store has a large capacity but a small duration (milliseconds). Info is always entering this store but will leave if not being payed attention to.
-If we pay attention to this info, this moves to the short term memory store
-Info in STM is used for immediate tasks. Has a limited duration and info will decay quickly if not rehearsed.
–If info is continuously rehearsed over a long time it moves into long term memory. This store has potentially unlimited capacity and duration
-When we need to use info from LTM we must retrieve it to transfer it back into STM.
Evaluate the multi-store model of memory
Scoville and Milner studied a man with brain damage who had his hippocampus removed. The man could remember things from before the surgery but could not form new LTM’s.This provides support for the MSM’s idea of separate stores as he could not transfer info from STM to LTM.
-The MSM suggests both STM and LTM are both single unitary stores. Research shows there are a number of qualitively different kinds of LTM e.g. maintenance rehearsal can explain long- term storage in semantic memory but does not explain episodic memory (experiences) in long term storage, which suggests the MSM may be overly simplistic.
-One limitation of research is that is is based on artificial tasks. e.g. in everyday life we from memory related to useful things - numbers, faces, places etc. However, many studies that support MSM use things like lists of numbers to remember which is not something we do daily. Therefore the MSM may not be a valid model of how memory works in everyday life so the creditability is reduced.
Who proposed the types of long term memory? What are the 3 types of memory?
Tulving
-Semantic
-Episodic
-Procedural
Outline semantic memory
memory for specific events that you have experienced
-ability to recall events in your life
-time-stamped - remember when they happened
-several elements - people + places involved
-conscious effort to recall - may be quick but you have to search for the information
e.g. a holiday
Outline episodic memory
contains your knowledge of the world
-our ‘dictionary’
-memories are not time-stamped
-less personal, more factual recall
e.g. learning the capital of France is Paris
Outline procedural memory
memory that enables you to perform a specific learned skill
-can recall without much conscious awareness or effort
e.g. riding a bike
Evaluate the types of LTM
-Case studies - HM - episodic memory impaired due to severe amnesia (had trouble remembering past events), but semantic memory was relatively unaffected (HM could not remember how to stroke a dog, but could remember the concept of a dog) - supports Tulving - different stores in LTM
-Neuroimaging evidence - Tulving et al used a PET scanner to scan brains whilst pps performed memory tasks
-found episodic + semantic memories were recalled from the prefrontal cortex, divided into the left + right hemispheres of the brain
-found the left side involved semantic memories, the right side involved episodic memories - scientific evidence to physically separate LTM stores - high validity
Who proposed the working memory model of memory?
Baddeley and Hitch (1974)
Outline the parts of the WMM
Central Executive
- main component
- controls + monitors the operations of the slave systems (other systems)
-limited capacity
-makes a decision about the data coming in and allocates it to a slave system
The Phonological Loop
- Articulatory Control System:
. subvocal repetition of info, prepares a person for speech
.the ‘inner voice’ - limited capacity (2 secs)
-Phonological Store;
.holds acoustic info (auditory coding)
.the ‘inner ear’ - limited capacity
The Visuo-Spatial sketchpad
- stores + processes visual + spatial info
-the ‘inner eye’
-limited capacity
-visual cache - stores visual data
-inner scribe - records the arrangement of objects in the visual field
Episodic Buffer
-the storage component of the central executive
-temporary store for visual, spatial and verbal information
-maintains a sense of time sequencing by recording episodes that are happening
Evaluate the working memory model
-Experimental evidence - dual performance task (pps given 2 tasks)
- 1. given a task that involved the VSSP and the phonological loop
-.2 given a task that involved using the VSSP for 2 things
-task 2 done more slowly, required more effort
-shows it is more natural for us to use 2 different slave systems at a time - evidence for separate STM stores
-Clinical evidence - KF - suffered from brain damage -memory studied - when things were said to him, he could not recall it, but when he read things, he could recall it. - provides evidence that there are separate stores in STM
Outline what is meant by interference as an explanation of forgetting
Interference is when one memory disrupts our ability to recall another. This is when memories conflict with each other and it usually happens when memories are similar, which results in one memory being forgotten or distorted
What is meant by proactive interference?
Learning that has occurred in the past interferes with our ability to learn in the current
e.g. if you are asked to recall a series of word lists, the later lists are not recalled as well as the first
What is meant by retroactive interference?
current attempts to learn something interfere with past learning
e.g. learning a new number and then forgetting your old number
Evaluate the theory of interference
-Lab experiments to come up with the theory use artificial material (list of words) that are unlike real life
- unlikely we remember word lists in daily life
-limitation because the use of artificial material makes interference much more likely in the lab, so may have low ecological validity as we do not know how far this explanation can be generalised for real life situations
-Lots of research has been conducted into interference in memory so there is lots of evidence
-most of these lab experiments show that interference is likely to be a very common way we forget info in LTM
-this is a strength as lab experiments have high control over extraneous variables, meaning they can test cause + effect - means highly valid results
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Outline retrieval failure as an explanation for forgetting
Occurs when we don’t have the necessary cues to access memory. The memory is available but not accessible unless a suitable cue is provided
cue - a ‘trigger’ of information that allows us to access a memory. Such cues ma be meaningful or may be indirectly linked by being encoded at the time of learning. For example, cues may be external - context dependent (environmental context), or internal - state dependent (mood)
Outline the key studies for context-dependent forgetting (external cues), and state-dependent forgetting (internal cues)
External cues - Godden & Baddeley
- divers learned a list of words either underwater or on land and then asked to recall the words either underwater or on land. These were the 4 conditions
-Learn on land > recall on land
-Learn on land > recall underwater
-Learn underwater > recall on land
-Learn underwater > recall underwater
Accurate recall was 40% lower in the non-matching conditions. The external cues were different from those at recall and this led to retrieval failure
Internal cues - Carter & Cassaday
-Gave anti-histamine drugs to pps. This created an internal physiological state different from the ‘normal’ state of being awake and alert.
Pps had to learn lists of words and then recall the info, again creating 4 conditions
-Learn on drug and recall on it
- Learn on it and recall not on it
- Learn not on drug - recall on it
- Learn not on drug and recall not on it
Memory was significantly worse where there was a mismatch between internal state at learning and recall. So when cues are absent, then there is more forgetting
Further evaluate the explanation of retrieval failure theory
Baddeley argues that context effects are actually not very strong, especially in real life. The contexts must be very different for an effect to occur, like land and underwater. This is a limitation because real-life application of retrieval failure due to contextual cues don’t actually explain much forgetting.
Explain factors that affect the accuracy of eyewitness testimonies.
Misleading information - incorrect info given to the eyewitness usually after the event. usually in the forms of leading questions and post-event discussion can affect how accurate the eyewitness recalls the event
Leading questions- a question which because of the way it is phrased, suggests a certain answer e.g. ‘Was their a knife in the accused left hand?’ suggests the answer is yes
Post-event discussion - occurs when there is more than 1 witness to the event. Witnesses may discuss what they have seen with co-witnesses, which may influence the accuracy of each witnesses’ recall of the event
Outline the study which tests how leading questions influence eyewitness testimonies
Loftus & Palmer
45 students shown 7 clips of road traffic accidents. After watching each clip, pps had to write an account on what they had just seen and to answer questions about the accident. The critical question was “About how fast were the cars going when they ‘ ‘ eachother?”
5 conditions to this question, pps only assigned 1 each. The blank space varied between 5 verbs (contacted, bumped, hit, collided, smashed)
Findings:
Contacted - 31.8 mph
Bumped - 34 mph
Hit - 38.1 mph
Collided - 39.3 mph
Smashed - 40.8 mph
This shows the way questions are worded can significantly affect recall of events in witnesses.
Explain why leading questions affect EWT
Response-bias explanation:
-suggests the wording of the question has no real effect on pps memories, but influences how they decide to answer. When a pp gets a leading question using the word ‘smashed’, this encourages them to choose a higher speed estimate
Substitute explanation:
-Loftus & Palmer conducted a second experiment that supports this explanation. The wording of a question actually changes the pps memory of the clip. Demonstrated because pps who heard ‘smashed’ later were more likely to report seeing broken glass (there was none) than those who heard ‘hit’. The verb altered their memory of the incident
Evaluate the study conducted by Loftus & Palmer
Watching clips are car accidents is artificial - lacks the stress + anxiety of actually witnessing the crash. Low ecological validity - may not be able to be generalised to real life crimes as the results may not be valid
PPs may show social desirability as they do not want to let down the researchers - influenced by demand characteristics - results may lack validity and therefore may not be able to be applied to real life situations
Outline the procedure testing how post-event discussion affects EWT
Gabbert et al
When post-event discussion occurs, memories may become contaminated by the other witnesses information and become combined.
In pairs, each pp watched a video of the same crime, but filmed from a different pov. Each pp could see elements of the event that the other could not. Both pps then discussed what they had seen before individually completing a recall test
Found 71% of pps mistakenly recalled aspects of the event that they did not see in the video but picked up from the discussion
0% of pps mistakenly recalled the event in the control group, where a discussion did not take place.
Concluded that witnesses often go along with eachother to win either social approval or because they believe the other witness to be correct and themselves wrong. Links to Asch’s study and normative/informational social influence
Evaluate the research into factors affecting EWT
A strength of the research is that it has practical uses in the real world, where there are real consequences of inaccurate EWT
Loftus believes leading questions in particular have a distorting effect on memory that police officers need to be aware of when phrasing questions to witnesses. This research can make a positive difference to peoples lives, improving the legal system.
Evidence that older ppl are less accurate than younger people when giving EWT
Anastasi & Rhodes found people aged 18-25 and 35-45 were more accurate than those aged 55-78. However, all groups were more accurate when identifying people their own age
What is anxiety?
A state of emotional and physical arousal. The emotions include having worried thoughts and feeling tense. Physical changes include an increased heart rate and sweatiness. It is a normal reaction to stressful situations, but can affect the accuracy and detail of EWT.
Outline the procedure testing anxiety having a negative effect on recall
Johnson & Scott
Anxiety creates physiological arousal in the body which prevents us from paying attention to important cues, so recall is worse.
PPs believed they were going to take part in a lab study. While seated in a waited room, pps heard an argument in the next room
Low anxiety condition- a man walked through the waiting area, carrying a pen with grease on his hands
High anxiety condition - also heard breaking glass. A man walked through with a paper knife covered in blood
The pps later picked out the man from a set of 50 photos
49% of pps in low anxiety condition could identify him
33% of pps in high anxiety condition could identify him
The tunnel theory of memory suggests a witness’ attention narrows to focus on a weapon, because it is a source of anxiety
Outline the procedure that tests anxiety having a positive effect on recall
The fight-or-flight response is triggered which increases our alertness and improves our memory for the event because we become more aware of cues
Study conducted on a real life shooting in a gun shop in Canada. The shop owner shot a thief dead.
Of the 21 witnesses, 13 agreed to take part in the study. Interviews were held 4-5 months after the incident and these were compared with the original police interviews made at the time of the shooting. Accuracy was determined by the number of details reported in each account. Witnesses asked to rate how stressed they felt during the incident on a 7-point scale, and if they had any problems since the event such as sleeplessness
Found witnesses were very accurate and there was little changes in accuracy after 5 months. Those who reported the highest levels of stress were most accurate
highest stress levels - 88% accurate
lowest stress levels - 75% accurate
Evaluate the effects of anxiety on EWT
Pickel proposed that reduced accuracy of identification due to the weapon focus effect may be due to surprise rather than anxiety. Arranged for pps to watch a thief in a salon carrying scissors (high threat, low surprise), gun (high threat, high surprise), wallet (low threat, low surprise), and a raw chicken (low threat, high surprise). Identification was least accurate in high surprise conditions rather than high threat - supports the view that weapon focus is related to surprise rather than anxiety
Ethical issues as pps are being placed into stressful situations, causing them anxiety without their full consent.
What is a cognitive interview?
a method of interviewing eyewitnesses to help them retrieve more accurate memories. It uses four main techniques.
Explain the 4 main parts to a cognitive interview (FIsher & Geiselman)
- Report everything - encouraged to include every single detail even if it seems insignificant or the witness is not confident on it, as this can help trigger other important details
- Context Reinstatement -
witness should return to the scene in the mind and imagine their environment and emotions at the time (links to context-dependent forgetting) - Recall in reverse order
- events are recalled in a different order to how they happened. Stops people from reporting expectations of how the event should happen, more likely to be accurate recall of events rather than a pre-scripted story - improves validity of recall - Recall from a changed perspective - witnesses should recall the incident from other people’s perspectives. done to disrupt the effect of expectations and schema on recall
What is the enhanced cognitive interview?
Developed version of the CI to focus on the social dynamics of the interaction. The interviewer is specially trained to know exactly when to give eye contact and when to stop it. The enhances CI also includes ideas such as reducing eyewitness anxiety, minimising distractions, and asking open-ended questions
Evaluate the cognitive interview
Time-consuming - takes longer than standard police interviews. must establish a relationship so witness feels comfortable. requires officers to be trained - expensive
Milne + Bull believe each CI element is crucial = does lead to discovery of new information
however, a combination of ‘Recall everything’ and ‘Context reinstatement’ produced better recall than any other condition
These findings are a strength as even if full CI is not used, using some elements of CI can help to improve recall
