Memory

Atkinson and Shiffrin (1968) proposed the MSM. This model assumes that there are three seperate memory stores:

Sensory Memory, Short-Term Memory, Long-Term Memory 

Evidence that there are seperate stores of long term memory and short term memory can come from PET scans. When the different stores are being used, different parts of the breain are shown to be active.

Duration - is how long a memory lasts before it is no longer available

Peterson and Peterson (1959)

• Set out to investigate the duration of STM
• 24 psychology students (participants) were briefly shown nonsense trigrams
• After, they were told to count backwards (to prevent rehearsal)
• They were stopped after different length intervals and then asked to recall the trigrams

They found that STM has a very brief duration when rehearsal is prevented. Recall after 3 seconds was 80% accurate and after 18 seconds only 10% accurate.

Evaluation:

• Lacks mundane realise as they were nonsense syllables, they were made up so cannot be applied to real life situations.
• The study cannot be generalised as it was carried out on 24 participants, meaning the sample is not representative.
• Lacks validity as it was only test on psychology students, therefore it cannot be used as a legitmate explanation of behaviour.

Bahrick et al (1975)

• Set out to establish the existence of VLTM and the difference between recognition and recall
• 392 graduates from an American High school aged between 17-74
• The carried out 4 tests that included: free recall of names, name and photo matching, name recognition and photo recognition

They found that in name and face recognition was 90% accurate all round, free recall was 60% after 15 years but only 30% after 48 years. They concluded that recognition is better than recall and classmates rarely forgot after recognition cues were given.

Evaluation:

• It has high validity because the information used was not random to the participants, therefore this research is a legitimate explaination of how memory works.
• It has high mundane realism due to the information having meaning, therefore it can be applied to real life.
• The study has external vaility, it was tested on a large and varied sample size, this means the findings can be generalised.

Capacity - this is how much can be held in the memory

Jacobs (1887):

• Set out to investigate the capacity of STM
• His participants were given a string of unrelated letters or digits, that increased by one each time.
• The way capacity was measured was at the point where participants could no longer recall the sequence correctly.

They found on average, the span for digits was 9.3 and for letters was 7.3, he therefore concluded that STM capacity was limited to 7 +/- 2.

Miller (1956):

Miller also found this and therefore came up with'Magic number7'. His theory is supported by numerous studies including Jacobs.

The capacity of LTM is said to be unlimited. No one has ever filled their long term memory and researchers can only use anecdotal evidence rather than experimental to find this out.

Encoding- encoding is the way in which infomation is processed so that it can be stored in the memory.

Conrad (1964):

• He set out to discover the effects of acoustic encoding in STM
• Participants were shown a random sequence of six consonants that were either acousticall similar or disimilar.
• After a presentation they were asked to write the letters down in order

They found that participants found it harder to recall leters that were acousticall similar, this shows that STM relies more on sound of words rather than their meaning.

Evaluation:

• Lacks mundane realism as the ltters were random, therefore it cannot be related to real life situations.
• Lacks internal validity as pariticpants kept making mistakes, this shows that the research may not be valid.

Baddeley (1966):

• Their aim was to discover the effects of acoustic and semantic coding in LTM
• Participants were divided into four groups and given a list of 10 words that were either acoustically similar or disimilar, semantically similar or disimilar.
• There was an interval were they were then given another task to do (to prevent rehearsal), then they had to recall the words.
• The procedure was repeated 4 times.

They found that recall was much worse when words were semantically similar 55% than disimilar 85%. Therefore they concluded that LTM makes use of semantic coding.

Evaluation:

• Lacks mundane realism as you wouldn't have the words in the same sentence, thereofre cannot be applied to real life.
• Lacks internal validity as it set out to test semantic and acoustic coding but only had results for semantic.

Most research that the MSM is based on is from lab experiments, e.g. Peterson and Peterson. This allows high levels of control over extraneous variables allowing us to determine cause and effect more easily.

The MSM was an early infuential model, this lead psychologists to investigate memory further. This was good because it increased our scientific understanding of how memory worked.

A negative of the MSM is that it is seen as over simplistic, it assumes that there is one STM store and one LTM store. Later research however shows that these stores are much more complex than that.

Baddeley and Hitch (1974)

They proposed an alternative model to explain STM, they didn't believe it was just 'one store' due to the fact you are able to do visual and audio tasks inaffected whereas 2 similar tasks are more difficult.

The Central Executive:

• This area controls attention and determines where information arriving needs to be sent.
• It briefly stores information and has a very limited capacity.

The Phonological Loop:

• This deals with only audio information.
• It consists of two parts: the phonological store that simply holds words you hear also known as the inner ear and the articulary process that is used for words that have been seen or heard which is also know as the inner voice.

Visuo-Spatial Sketch Pad:

• Here visual and spatial information is temporarily stored.
• It is used for tasks such as counting windows on your house.

The Episodic Buffer:

• This is stored unit and can hold visual and auditory information.

Evidence for the relationship between components:

• Baddeley and Hitch (1974) gave participants a dual task.
• One was reading aloud and the other was checking sentences.
• They found that participants were able to do both tasks very well simultaneously.

This shows that STM must have different components that can process more than one type of information at a time.

• Baddeley et al (1973) also gave participants a dual task.
• One was trackiing a moving spot of light and the other was visual imagery.
• They found that participants were much poorer at the dual task compared to performing them seperately.

This is because both tasks needed the visuo-spatial sketchpad meaning they were competing for the same resource.

If huge demand is placed on one of the slave systems, it is the job of the central executive to rellocate resources to another slave system where it is needed more. E.G. you may need to concentrate on something more than another.

There is concern on the central executive as to what it actually is. Some psychologists feel it is too vague and doesn't explain much especially as it being the most important part of the model.Evidence from brain damaged patients suggests that is can be divided into two however this is not shown in the model, this is a limitation to the study as it means it is incomplete, therefore reducing its usefulness.

Evidence for this model comes from a lot of studies of brain damaged patients, by doing this we are unable to make a before and after comparison. This means that we cannot be sure their memory has changed due to the brain damage e.g KF study. Therefore we are unable to identify cause and effect and validity of the model is reduced meaning it cannot be used as a legitimate model of memory.

A strength of this model is the use of PET scans to establish the use of different parts of the brain for visual and verbal tasks. This is biological evidence that supports the existence of the phonological loop and visuo-spatial sketchpad that are components suggested by the WMM, therefore has high mundane realism as it mirrors the real world.

This is the evidence given in court or at police investigations by someone who has witnessed a crime or accident.

There are several factors that affect the accuracy of eyewitness testimony:

• Misleading information
• Anxiety
• Age

There are 3 stages of eyewitness testimony:

The witness first encodes details of the event into their LTM, they then retain the information for a period of time and finally the witness retrieves the memory from storage. This reconstruction of memory can be affected by the way questions are asks and cues that are given.

Loftus and Palmer (1974)

• They set out to investigate the effect of misleading information on the accuracy of EWT
• They took 45 participants split them into 5 groups and they were shown 7 films of different car accidents.
• After each film they given a set of questions including one important question of how fast the car was going.
• Each group was given this question however the verb was changed to either hit, smashed, collided, bumped or contacted.
• They calculated the average speed recorded by participants, the word smashed recorded a higher average speed of 41mph and the lowest average speed was contacted at 32mph.

They concluded that misleading information can reduce the accuracy of eyewitness testimony. In their study they showed how strong the effect is as one word was able to change the speeds recorded by participants.

Loftus and Palmer - Evaluation:

The study can not be a representative of real life as it was a lab experiment. People may not take them seriously/be emotionally aroused as they would be in a real incident. Yuille et al found arousal enhances accuracy of memory, therefore ecological validity is reduced as participants may not display their natural behaviour as they would in a real life situation.

The study is seen as very reliable by other psychologists, this study has been replicated many times and the findings have been the same. This therefore shows a high level of consistency and accuracy of the study showing it can be trusted.

A strength of this study is the clear real life application as videos of car accidents were used. This gives researchers more accurate results, which were found as a negative impact on leading questions. This allows proffesionals who use EWT to be more careful with the way they word questions that can lead to a lower rate of false convictions.

Anxiety is the state of heightened arousal due to a danger or threat. There are studies that say anxiety has a positive effect on recall, but others that found it has a negative effect.

Christianson et al (1993):

• They set out to investigate the effect of anxiety on EWT.
• They surveyed 110 people who has witnessed 22 different bank robberies.
• They were either bystanders or direct victims of the incident.

They found that participants who experienced higher levels of anxiety (direct victims) had more detailed and accurate recalls than those who were bystanders. They concluded that anxiety improves accuracy of EWT.

Loftus (1979):

• Set out to investigate the effects of anxiety on EWT.
• Conducted a lab experiment where participants were asked to stand outside a lab where they thought they were listening to a genuine converstation.
• Those in condition 1 overheard a conversation, followed by a man coming out of the room holding a pen with grease on his hands.
• Those in condition 2 overheard a more heated conversation and the sound of funiture being moved. This was followed by a man carring a blood stained knife.
• Both groups were then asked to identify the man from a set of 50 photos.

They found participants who had witnessed a more violent scene were more anxious and therefore less accurate when identifying the man (33%) compared to those in a low anxiety condition (49%). They concluded that anxiety can worsen the accuracy of EWT

Loftus identified this as the weapon focus effect, this is where participants focus more on the weapon than the facial details of the culprit therefore making recall less accurate.

Due to different studies suggesting different things about the effects of anxiety on EWT, they set a compromise. It said there is a certain point (optimum) where anxiety increases alerness and focus however past this point the witness becomes too distressed to take in any detail.

A major strength of Christianson et al study is the clear real life application, however because participants were asked to recall a distressing event in artificial conditions it breaches the protection from harm ethical guidelines. Therefore this study does not take into account ethical guidelines and participants may not have been debriefed about this before taking part.

Loftus' study is a lab experiment, meaning participants may not experience the same level of emotional reaction that they would in real life so natural behaviour is not demonstrated. This reduced ecological validity meaning the study cannot be generalised to other situations.

Loftus' study found the negative effects of anxiety on the accuracy of EWT, this means now investigators do not rely on EWT as much as they did in court. This has increased the use of hard evidence such as DNA in court which can lead to a lower rate of false convictions.

The age of the witness is also thought to influence how accurate their testimoney will be, there is evidence for adults being more accurate but also inaccurate.

Yarmey (1993):

• Stopped 651 adults in public places.
• They asked them to recall the physical characteristics of a young woman they had briefly spoken to 2 minutes before.
• Younger adults were more confident with their recall however there was no significant difference in accuracy to recall in comparison to older adults.

Parker et al (1989):

• Compared primary school children and college students in their ability to correctly identify a target individual after being briefed about a mock crime.
• Children had a higher rate in photo identification however were more likely to make mistakes.
• Overall they concluded that children were more accurate in EWT.

Own age bias is a huge limitation to many studies carried out investigating EWT.

This is because of the differential experience hypothesis created by Brigham et al that says the more contact you have with a particular age or ethnic group, the better the memory would be for such individuals.

Therefore studies have not taken into consideration of age groups having superior memory for faces in their own age group, meaning findings are invalid and cannot be use when applying to everyday life.

This is a police technique for interviewing witnesses to a crime, which encourages them to recreate the original context in order to increase the accessibility of stored information.

Our memory is made up of a network of association rather than discrete events, memories therefore can be accessed through retreival strategies.

• Report everything: witnesses might not realise that some details are important and they may help recall significant information.
• Mental rienstatement: recalling how you felt and the context enhances recall (cues). This includes the environment and how they were feeling at the time.
• Change narrative order: witnesses reconstruct based on their schemas when in a forward order, if order is changed it may be more accurate.
• Recall with perspective change: witness is asked to recall the event from different points of view, this encourages many retreival paths.

Fisher et al added a few extra features to the cognitive interview, these include:

No distractions, open questions, active listening, no interuption and speaking slowly.

Instructions of this technique may be too complicated for children to understand, as a result it can reduce a childs accuracy at recalling events.Therefore this limits the techniques usefullness so we are unable to generalise it as it cannot be applied to all situations.

This technique is only usefull when used within a short period of time of the crime happening. Fisher et al found that the technique wasn't as effective with crimes that happened a longer time after they were interviewed than those in short space of time suggesting they will recall more when they haven't had a long period after the crime has happened.

Adequate training is necessary for cognitive interview to be effective. Most police officers are not given this training and do not have the time to conduct a full cognitive interview during their investigations.This therefore reduces the effectiveness of the technique as it can lead to less informatio being available from EWT.

Mnemonics is another word for memory tool, they are techniques for remembering information that otherwise is quiet difficult to recall.

2 main stategies are:

• Verbal Mnemonics
• Visual imagery mnemonics

How do the techniques work?

Role Of Organisation - By organising data we establish links that help with recall, word association and visual imagery create links. Organised informaion is found a lot faster.

Role OF Elaborative Rehearsal - these techniques make us elaborate the information so that it is remembered. The amount of rehearsal is improtant but the nature of rehearsal/elaboration is more important.

Dual Coding Hypothesis - Pavio proposed that words and images are processed seperately, words that can be made into images are then dual coded increasing our likelyhood of remembering that information.

Visual imagery mnenomics:

• Method of loci - Loci means places, you associate parts of the material to be recalled with different places, rooms or sites in order that they are to be recalled. This creates a memory link and you are able to remember it more easily.
• Key word method - This is used to associate two pieces of information.

Verbal mnemonics:

• Acronym - This is where a word or sentence is formed from the initial letters of other words
• Chunking - Involves dividing a long string of information into memorable chunks.  We are able to then pack more information into our memory (7+/- 2)

Evaluation:

These stategies are very reliable, they reduce the time it takes to learn specific information and they involve very little effort. These techniques are therefore very useful in real life applications as many different groups of people use them for many different reasons.

However not all strategies work with all types of information and they do not work for all types of people, these reasons therefore reduce the effectiveness of the techniques are they are unable to be used by everyone in every situation.