Memory

• Capacity of STM and LTM

  • George Miller- concluded that the span of immediate memory is about 7 items
  • He noted that people can count 7 dots flashed onto a screen, but not many more.
  • The same is true if asked to recall music notes, letters and even words
  • Miller also found that people can recall 5 words as well as they can recall 5 letters- we chunk things together and can then remember more
  • The capacity of the LTM is potentially infinite
• Duration of STM

  • STM- Lloyd and Peterson- studied the duration of STM, using 24 students. Each participant was tested over 8 trials.
  • In each trial they were asked to recall a consonant syllable and a three-digit number, from between 3-18 seconds.
  • During this period they had to count backwards from their three digit number
  • 3 seconds- 90% correct, 9 seconds- 20% correct, 18 seconds- 2% correct
  • Suggests STM has a very short duration, as long as verbal rehearsal is prevented
• Duration of LTM

  Bahrick et al. tested 400 people of various ages on their memory of classmates. A photo-recognition test and free recall was used

  15 years of graduation- 90% identifying faces, 48 years of graduation- 70% identifying faces

  15 years of graduation- 60% free recall, 48 years of graduation- 30% free recall
• Coding of STM and LTM

  Information we store has to be ‘written’ in memory in some form- it is described as a ‘code’ in which it is held in the form of sounds (acoustic), images (visual), or meaning (semantic)

  Baddeley- used semantic and acoustic word lists to test their effect of STM and LTM.

  Participants had difficulty remembering acoustically similar in STM, but not LTM

  Participants had difficulty remembering semantically similar in LTM, but not STM

  Suggests STM is coded acoustically, where LTM is coded semantically
• MSM key points

  The MSM was first described by Atkinson and Shiffrin in 1968

  It is called ‘multi store’ because it consists of three memory stores, linked to each other because the processes that enable transfer of information from one store to the next
• MSM- Sensory register

  The place where information is held at each of the senses- eyes, nose, etc, and the corresponding areas of the brain

  These registers have a very large capacity

  The sensory registers are constantly receiving information, but most of this receives no attention and remains in the sensory register for milliseconds

  If a person’s attention is focused on one of the sensory stores, then the data is transferred to the STM
• MSM- short-term memory store

  Information is held in STM so it can be used for immediate tasks

  STM has a limited duration - it is in a 'fragile' state and will disappear (decay) relatively quickly it it isn't rehearsed.

  STM has a limited capacity- information will disappear from STM if new information enters STM, pushing out (or displacing) the original information.
• MSM- long-term memory store

  LTM is potentially unlimited in duration and capacity.

  You may feel that there are many things you once knew but have forgotten, but the evidence suggests that either you actually had never really made the memory permanent or it is there, you just can't find it

  The process of getting information from LTM involves the information passing back through STM. It is then available for use.
• MSM- maintenance rehearsal

  • Repetition keeps information in STM but eventually such repetition will create a LTM
  • Repeating information over and over again is called maintenance rehearsal. It is mainly acoustic
  • Atkinson and Shiffrin proposed a direct relationship between rehearsal in STM and the strength of the LTM- the more the information is rehearsed, the better it is remembered.
• The WMM key points

  Baddeley and Hitch (1974) felt that the STM wasn’t just one store, but a number of stores.

  They thought this because if you do two things at the same time (dual task performance) and they are both visual tasks, you perform less well than if you were to do them separately

  This suggests there are separate stores for different processes
• Episodic memory

  • ‘Episodic’ comes from ‘episode’- an event of a group of events occurring as part of a larger sequence
  • It is explicit memory
  • Concerned with personal experiences. You may recall the time and place of such events as well as who was there
  • You may also recall associated emotions felt at the time
  • Episodic memories have three elements- specific details, context and emotion
• Semantic memory

  • Knowledge about the world which is shared by everyone rather than the personal kind of knowledge that is classed as episodic memories.
  • Semantic memories may relate to things, to what behaviour is appropriate, and abstract concepts
  • They generally begin as episodic memories because we acquire knowledge based on personal experiences.
  • There is a gradual transition from episodic to semantic memory where the memory slowly loses its association to particular events, so that the information can be generalised
• • Procedural memory
  • Concerned with skills, such as knowing how to tie a shoelace
  • About remembering how to do something rather than knowing the rules of what to do
  • Acquired through repetition and practice.
  • This kind of memory is implicit. We are less aware of these memories because they have become automatic.
  • If you try to think too much about such procedural memories it prevents you acting them out.
  • Attention to the step-by-step procedure disrupts the automatic performance.
  • It is important that procedural memories are automatic so we can focus our attention on other tasks
• Retroactive interference

  • Georg Müller and his students were the first to identify retroactive interference effects.
  • They gave participants a list of nonsense syllables to learn, and then, after a retention interval, asked them to recall the lists
  • Performance was worse if participants had been given an intervening task between initial learning and recall
  • The intervening task produced retroactive interference because the later task of describing pictures interfered with what had previously been learned
  • Retroactive interference- current attempts to learn something interfere with past learning
• Proactive interference

  • Underwood analysed the findings from a number of studies and concluded that when participants have to learn a series of words they don’t learn the lists encountered later on in the sequence as well as lists of words encountered earlier on
  • Overall, Underwood found that if the participants memorised 10 lists, recall after 24 hours was 20%
  • For participants who only learned one list, recall after 24 hours was 70%
  • Proactive interference- past learning interferes with current attempts to learn something
• Real world study of interference

  • Baddeley and Hitch investigated interference effects in an everyday setting of rugby players recalling the names of the teams they had played against
  • Some players played in all of the games in the season whereas others missed some games because of injury.
  • The time interval from start to end of the season was the same for all players but the number of intervening games was different for each player because of missed games.
  • Those players who played most games forgot proportionately more because of interference
• The encoding specificity principle

  • Tulving proposed that memory is most effective if information present at encoding is also available at the time of retrieval.
  • The ESP further states that a cue doesn't have to be exactly right but the closer the cue is to the original item, the more useful it will be.
  • Whenever any information is learned, we also often remember the environmental context or our emotional state at the time.
  • This information is encoded to varying degrees along with the material learned.
  • Being reminded of a particular place or mood can act as a cue to help access a memory.
• Context-dependant forgetting

  • A study by Godden and Baddeley investigated the effect of contextual cues.
  • Scuba divers were participants and they had to learn a set of words either on land or underwater.
  • Subsequently, they were tested either on land or underwater, so there were again four experimental conditions.
  • The results again showed that highest recall occurred when the initial context matched the recall environment, e.g. learning on land and recalling on land.
  • Context-dependent forgetting- The physical location one is in at the time of learning acts as a cue for memory
• State-dependant forgetting

  Goodwin et al. (1969) asked male volunteers to remember a list of words when they were either drunk or sober.

  The participants were asked to recall the lists after 24 hours when some were sober but others had to get drunk again.

  The recall scores suggested that information learned when drunk is more available when in the same state later.

  State-dependent forgetting- The mental state one is in at the time of learning acts as a cue for memory
• Loftus and Palmer experiment 1

  45 students were shown seven films of different traffic accidents. After each film the participants were given a questionnaire including one critical question about ‘how fast were the cars going when they hit/smashed/collided/bumped each other?’

  Smashed- 40.8 mph

  Collided- 39.3 mph

  Hit- 34.0 mph

  Contacted- 31.8 mph
• Loftus and Palmer experiment 2

  • The leading question may bias a ptp's response or may actually cause information to be altered before it is stored.
  • To test this, a new set of participants were divided into three groups and shown a film of a car accident lasting 1 minute, and again asked questions about speed.
  • The ptps were then asked to return one week later when they were asked the critical question, of ‘Did you see any broken glass?'
  • There was no broken glass in the film but those who thought the car was travelling faster might be more likely to think that there would be broken glass.
• Post-event discussion

  • The memory of an event may also be altered or contaminated through discussing events with others and/or being questioned multiple times
• The conformity effect

  • Co-witnesses may reach a consensus view of what actually happened
  • Fiona Gabbert- Participants were in pairs where each partner watched a different video of the same event so that they each viewed unique items.
  • Pairs in one condition were encouraged to discuss the event before each partner individually recalled the event they watched.
  • A very high number of witnesses (71%) who had discussed the event went on to mistakenly recall items acquired during the discussion.
• Repeat interviewing

  Each time an eyewitness is interviewed there is the possibility that comments from the interviewer will become incorporated into their recollection of events.

  It is also the case that an interviewer may use leading questions and thus alter the individual's memory for events.

  LaRooy- This is especially the case when children are being interviewed about a crime
• Anxiety has a negative effect on accuracy

  Anxiety might reduce the accuracy of EWT is the weapon focus effect- a weapon in a criminal's hand distracts attention (because of the anxiety it creates) from other features and therefore reduces the accuracy of identification.
• Anxiety has a negative effect on accuracy- Johnson and Scott (1976) procedure and findings

  • Procedure- Johnson and Scott asked participants to sit in a waiting room where they heard an argument in an adjoining room and then saw a man run through the room carrying either a pen covered in grease or a knife covered in blood. Participants were later asked to identify the man from a set of photographs.
  • Findings- supported the idea of the weapon focus effect.
  • Mean accuracy was 49% in identifying the man in the pen condition, compared with 33% accuracy in the knife condition.
• Anxiety has a negative effect on accuracy- Johnson and Scott (1976) conclusions

  Loftus et al.- anxiety does focus attention on central features of a crime (e.g. the weapon).

  The researchers monitored eyewitnesses' eye movements and found that the presence of a weapon caused attention to be physically drawn towards the weapon itself and away from other things such as the person's face.
• Anxiety has a positive effect on accuracy

  High anxiety/arousal creates more enduring and accurate memories.

  There is an evolutionary argument that suggests it would be adaptive to remember events that are emotionally important so that you could identify similar situations in the future and recall how to respond
• Anxiety has a positive effect on accuracy- Christianson and Hubinette (1993)

  • Procedure- questioned 58 real witnesses to bank robberies in Sweden. The witnesses were either high anxiety victims or low anxiety bystanders
  • The interviews were conducted 4-15 months after the robberies.
  • Findings- all witnesses showed generally good memories for details of the robbery itself (better than 75% accurate recall).
  • Those witnesses who were most anxious (the victims) had the best recall of all. This study generally shows that anxiety does not reduce accuracy of recall.
• The Yerkes Dodson Effect

  Deffenbacher reviewed 21 studies of the effects of anxiety on eyewitness memory.

  He found that 10 of these studies had results that linked higher arousal levels to increased eyewitness accuracy while 11 of them showed the opposite.

  Deffenbacher suggested that the Yerkes-Dodson effect can account for this apparent inconsistency.

  According to this principle there would be occasions when anxiety/arousal is only moderate and then eyewitness accuracy would be enhanced. When anxiety/arousal is too extreme then accuracy will be reduced.
• Cognitive interview key facts

  Cognitive interview- a police technique for interviewing witnesses to a crime, which encourages them to recreate the original context of the crime, increasing the accessibility of stored information

  Geiselman (1984) developed an interviewing technique called the cognitive interview, which was based on proven psychological principles concerning effective memory recall.
• Cognitive interview- 1. Mental reinstatement of original context

  Where the interviewer encourages the interviewee to mentally recreate both the physical and psychological environment of the original incident.

  The aim is to make memories accessible. People often cannot access memories that are there. They need appropriate contextual and emotional cues to retrieve memories.
• Cognitive interview- 2. report everything

  The interviewer encourages the reporting of every single detail of the event without editing anything out, even though it may seem irrelevant.

  Memories are interconnected with one another so that recollection of one item may then cue a whole lot of other memories.

  The recollection of small details may eventually be pieced together from many different witnesses to form a clearer picture of the event.
• Cognitive interview- 3. change order

  • The interviewer may try alternative ways through the timeline of the incident, for example by reversing the order in which events occurred.
  • Our recollections are influenced by schemas. For example, if you think about when you went to a restaurant a few weeks ago your recollection will be influenced by your general expectations of what is likely to happen at a restaurant
  • If you have to recall the events starting from the end of the event backwards this prevents your pre-existing schema influencing what you recall.
• Cognitive interview- 4. change perspective

  This approach was suggested by the research by Anderson and Pichert

  The interviewee is asked to recall the incident from multiple perspectives, for example by imagining how it would have appeared to other witnesses present at the time.

  This is again done to disrupt the effect that schemas have on recall.