Factors that affect short term memory (STM)
- grouping numbers and/or letters in a recognisable pattern with a particular rhythm
- chunks tend to be 2-6 individual characters
- makes remembering individual characters easier
- affects STM by increasing the capacity as it is a form of repetition (read it, say it, hear it)
- the shorter the time a word takes to pronounce, the easier it will be to remember
- the longer the time a word takes to pronounce, the more it will need to be repeated
- study done on this: Narah-Benjamin and Ayres (1986)
- effects of medication, drugs, alcohol, smoking, syndromes, illness, sleep deprivation and more
Duration of short term memory (STM) - Petersons
Definition of duration
- How long information is stored in memory
Peterson and Peterson (1959)
- Participants* shown a nonsense trigram (three constonants used to make a 'word' e.g DVM) for one second.
- Nonsense tirgram taken away from view and participants given a three digit number.
- Participants asked to count backwards in 3's for 3-18 seconds.
- Participants asked to write down the nonsense trigram.
*24 university students
Peterson and Peterson continued
- 90% short interval, 2% long interval (correct nonsense trigram).
- Information remains in STM for up to 18 seconds if rehearsal is prevented.
- The duration of short term memory is 18 seconds.
- Low in ecogolical validity (not a real life situation)
- Relates to one aspect of memory only.
- Low in population validity (based on university students)
Duration of long term memory (LTM) - Bahrick study
- Photo-recognition: 400 participants (17-74 yrs) shown 50 photos from their year book and asked to identify.
- Free recall: participants asked to write down the names of the members of their graduating class.
- When tested within 15 years of graduation: 90% accuracy in photo-recognition and 60% accuracy in free recall.
- When tested within 48 years of graduation: 70% accuracy in photo-recognition and 30% accuracy in free recall.
- Recognition gained a higher accuracy rate overall than recall.
- Memories are always there but we often need a cue to prompt them.
- In real life, our memory holds a lot of information but we cannot always recall it.
- Possibility of extraneous variables.
- High in ecological validity.
Encoding - Baddeley study
Definition of encoding
- The way information is stored in memory. (All information is rewritten in order to be stored)
- Participants presented with a list of five words and asked to write down immediately after hearing the entire list. This is repeated several times with different lists, some containing specifically similar words. (STM)
- Participants presented with a list of ten words and are interrupted from rehearsing. The lists are repeated four times and are then written down after a 20 minute interval. (LTM)
- When testing STM, participants remembered less words from the acoustically similar list. (e.g mad, map, mat, cat, cap - sound similar) Therefore, STM encodes acoustically. We know this because acoustic confusion highlights it.
- When testing LTM, participants remembered less words from the semantically similar list. Therefore, LTM encodes semantically.
Characteristics of short term memory
Short term memory (STM)
Capacity - 7 +/- 2 items of information
Duration - Up to 18 seconds
Encoding - Acoustic
Short term memory is a limited storage for information with a capacity of 7 +/- 2 pieces of information, lasting in the storage unit for a duration of 18 seconds. It is encoded acoustically.
Characteristics of long term memory
Long term memory (LTM)
Capacity - Unlimited
Duration - 2 minutes to a lifetime depending on the type of information
Encoding - Semantic
Long term memory is an unlimited storage for information with a capacity that cannot be measured (limitless), with a duration ranging from 2 minutes to a lifetime. It is encoded semantically.
The multi-store model of memory (MSM) - EXAM Q
Outline and evaluate the multi-store model of memory. (12 marks)
The multi-store model of memory was produced by Atkinson and Shiffrin in 1968. Information from the environment enters the sensory memory stoage unit via the five senses. Studies have suggested that that sensory memory has a capacity of 12 items and a duration of 1-2 seconds. At this stage, the sensory memory unit will filter out unnecessary information, causing it to be forgotten although you were never consciously aware of it. As soon as you pay attention to the information though, it enters your short-term memory storage unit. In this model, short-term memory is seen as a single storage unit where 7 +/- 2 items of information can be stored for up to 18 seconds. If information is not rehearsed 1-1000 times, then information in your short-term memory unit will decay after the 18 seconds, ultimately being forgotten. Information encodes from acoustics in short-term memory to semantics in long-term memory. When you need certain information, it is retrieved from the unlimited storage unit, long-term memory into short-term memory. The new information may replace the old information retrieved (displacement). This information can stay in long-term memory from 2 minutes to a lifetime but decays if not used. (AO1)
The multi-store model of memory (MSM) - EXAM Q
The multi-store model has been supported by Peterson and Peterson as they have shown that rehearsal is essential in remembering information. In their experiment, participants were asked to recall nonsense trigrams after counting backwards for varying amounts of time. It was found that few participants remembered letters after 18 seconds. This therefore highlights the need for rehearsal but also that short-term memory has a limited duration and is distinct from long-term memory. All of which is mentioned in the multi-store model. (AO2)
The model has also been supported by Glanzer and Cunitz as they have proven the need for rehearsal and that there is a distinct difference between short-term and long-term memory. In their experiment, participants were given a list of 20 words and were then asked to recall them. It was found that participants remembered more words from the beginning and end of the list than in the middle. The serial position curve highlights the need for rehearsal and a difference between the stores through words at the beginning of the words being rehearsed and therefore processed into long-term memory (primacy effect) whilst words at the end of the list being remembered as they are still in short-term memory (recency effect). Also, the serial position curve distinguishes a difference between the stores which is represented in the multi-store model of memory. (AO2)
However, Eysneck and Keane have stated that the model is oversimplified. They backed up this statement by considering everything we store in long-term memory. We store things such as 2+2=4 and that Justin Timberlake is a postar and knowing what we had for breakfast in our long-term memory. Surely all this information cannot be stored in one unit. Therefore, the multi-store model is oversimplified as showing that long-term memory is a single storage unit and that all information is piled into one box within our memory - surely information is stored into groups (e.g maths, food, conversation). (AO2)
This shows that the multi-store model of memory has both positive and negative points surrounding its accuracy. It should also be mentioned that flashbulbs do not support the multi-store model in its need for rehearsal. Flashbulbs do not need to be rehearsed, details are simply remembered because of the significance of the event. (AO2)
The working memory model (WMM) - EXAM Q
Outline and evaluate the working memory model. (12 marks)
Baddeley and Hitch (1974), produced the working memory model which shows the process of short-term memory. Information from the surrounding environment enters the central executive via the five senses. The central executive is a control system which is in charge of attention, rehearsal and retrieval. Verbal information such as listening, talking, reading and writing enters the phonolgical loop and is then rehearsed or stored. If the information is not used, it simply decays. This is one of the two slave systems and has a duration of 2 seconds. The slave systems are a two way process which, when the central executive is full, takes information from it in order to free space. The visual and spatial information, such as pictures and 3D depth, enters the visuospatial sketchpad which also has a duration of two seconds and if the information is not used, it simply decays. Soon after, Baddeley and Hitch added another section called visioscribe (rehearsal) and visiocache (storage) which takes this information from the visuospatial sketchpad. If not needed, it simply decays. (AO1)
The working memory model (WMM) - EXAM Q
Shallice and Warrington supported the working memory model in its entirety by showing that short-term memory is not a single storage unit. They studied a patient with poor short-term memory and it was found that the deficit was only limited to verbal manner and not meaningful sounds. This therefore highlights that short-term memory is not simply one unit, but it is divided into sections. This is shown in working memory model. (AO2)
A study produced by Baddeley, Thomson and Buchanan (1975) shows evidence for phonological loop. In their experiment, they showed participants a visual presentation of words for a very short period of time. There were displays of a set of short words as well as a set of long words. It was found that more people recalled more short words than long words. This concluded that the capacity of the loop os determined by the length of time it takes to say the word. This is displayed in the working memory model. (AO2)
The main studies supporting the working memory model have been done by Baddeley, one of the two persons that created the model. This poses a lot of proble,s including that of researcher bias. He claims to have tested many things that cannot be tested individually, yet suggests that they have a capacity. (Central executive, for example). This raises questions such as; do the sub-sections actually exist and were the tests actually done? Also, there are not many results to these 'tests' suggesting that the real results were not published in order to prove the model correct and to not degrade his work. This highlights that the studies and the model need to be viewed carefully. (AO2)
The working memory model has both positive and negative points towards it, but it should also be mentioned that psychologists have disproved this model claiming that it is improper and missing detail. Many studies have found evidence for sensory memory and processes between short-term memory and long-term memory, but none of this is portryaed within the working memory model. This shows that it is not a full representation of memory. (AO2)
Eye Witness Testimony (EWT)
- All research has been conducted during the time period 1970-1980.
Definition of an eye witness testimony
- An eye witness is someone who has witnessed an event and is asked to recall what has happened, normally through interviews and/or police interviewing.
- Attention - is focused on a specific aspect causing other details to be missed (decreases accuracy)
- Retain - talk to others after an event and hear their version causing your memory trace to be altered (displacement)
- Retrieval - Police used to use leading questions encouraging wrong answers (incorrect statement)
Negatives of eye witness testimony
- Fruzetti et al (1992) suggested that thousands of people are wrongly convicted each year due to eye witness testimony.
- Kebbel and Milne (1998) survey found that juries and British Police rely heavily on eye witness testimony.
Eye Witness Testimony - Loftus (1975)
- Participants shown a film of events leading up to a car accident and then split into two groups (a control group and an experimental group).
- Participants asked questions about what they had seen: control group asked questions in relation to what they'd seen, whereas, experimental group asked a question including misleading information (they were asked if they had seen the barn which in fact did not exist).
- 17% of experimental group reported seeing the barn.
- 3% of the control group made the same error with a leading question.
- Some partiticpants given the misleading post-event information absorbed it as being what they had actually seen.
- Artificial situation - controlled lab experiment with realistic material.
- Low ecological validity - participants knew they had to pay attention, in real life they would not be pre-prepared.
- Some critics say the participants were subject to demand characteristics.
- Investigators must obtain full consent from participants - Loftus could not so that they could not guess the hypothesis.
- Participants must not become subject to psychological harm - watching a car accident could be distressing for some.
Eye Witness Testimony - Loftus studies
Loftus and Zanni (1975)
- Participants shown brief film clips about a car accident.
- Half of participants asked if they'd seen 'a' broken headlight, whilst the other half were asked if they had seen 'the' broken headlight.
- Although there was no broken headlight in the film, 17% asked 'the' reported seeing one and 7% asked 'a' made the same error.
Loftus and Palmer (1974)
- Participants shown a short film of a car accident and then asked a series of questions.
- Crucial question concerned the speed of the car on impact.
- One group was asked 'How fast were the cars going when they hit each other?' The other was asked the same using different verbs.
- 'Smashed' produced the highest estimate.
- 'Contacted' produced the lowest estimate.
- A week later, participants asked 'smashed' reported seeing glass when there was none.
Factors affecting eye witness testimony (EWT)
- Heightens the body's responses and gets ready for fight or flight (stress and adrenaline).
- Yerkes and Dobson Law: looks at the impact of anxiety on a memory recall or performance.
- A graph for which would look like an upside down 'U', with 'Memory Recall/Performance' on the y-axis, and 'Anxiety Level' on the x-axis.
- Small amount of anxiety improves recall performance because attention is focussed due to the situation being unusual.
- Too much anxiety decreases memory recall - a traumatic experience causes us to recall less due to panic and fear.
- Young children make poor witnesses because they feel as though they may get in trouble and so do not tell the full story. Also, they are easily influenced and will do what people tell them to.
- The elderly also make poor witnesses because their memories aren't that good for new information due to natural deterioration.
Memory Improvement Strategies - Meaning
- Bartlett argued that we remember things because they are meaningful to us.
Craik and Tulving (1975)
- Participants were shown a series of words, on each of which they were asked a question. The questions required either structural, phonological or semantic processing.
- Participants were then given an unexpected recognition task, in which they were asked to pick out the words that they had been shown from others they had not seen.
- Participants were significantly better at identifying words that they had processed semantically than those they had processed structurally or phonologically.
- This highlights that if people were to remember things based on its meaning then they would remember more because they would have associated it to similar things and stored the information in the relevant schemas.
Memory Improvement Strategies - Organisation
- Organisation of information in LTM is essential for recall.
- Recall is something that we do automatically to a certain extent.
- There must be a form of system that enables us to access information quickly and easily through categories.
- Participants were asked to learn 60 words, 15 in each of four categories - vegetables, animals, names and professions - presented in a random order.
- They were then asked to recall as many as possible in any order.
- There was a tendency to recall the items in clusters.
- Material is organised in LTM in categorical clusters.
Memory Improvement - Encoding Specificity Principl
- Tulving suggested that we remember information better if we recall it in the setting in which we saw, learnt or remembered it.
- This means that we would do better in exams if we sat them in the room in which we learnt the new information.
- This explains the situation where you get up to get something and forget what it was once you move then remember when you go back to where you were.
- The idea is that the cues in the environment help us to remember the information we are looking for.
Method of Loci
- This involves putting objects you need to remember along a memorable route.
- People remembering a shopping list will associate the items on their list to significant points along the route.
- This enhances memory as people are encoding the word both visually and verbally.
Craik and Lockhart's levels of processing model (1972)
- Structural level (What does the word look like? e.g capitals or lower-case letters?) - Shallow processing
- Phonological level (What does the word sound like? e.g does it rhyme with 'cat'?) - Deep processing
- Semantic level (What does the word mean? e.g is it a type of food?) - Deeper processing