Memory

• Encoding


  Storing information in different formats
• Baddeley's study


  • Visually presented students with letters one at a time
  • Found letters which are acoustically similar are harder to recall than acoustically dissimilar
  • Participants did worse with acoustically dissimilar words when asked to recall after 20mins
• Artificial stimuli used rather than meaningful material. The words had no personal meaning so tells us little about everyday memory tasks. Therefore findings can't be generalised to everyday memory tasks and study lacks validity.
• Capacity


  How much information is stored in STM and LTM
• Jacobs' study


  • Researcher gives 4 digits and participant must recall these correctly
  • If correct, another digit is added until participant can't recall the order correctly
  • Found mean span for digits was 9.3 and letters is 7.3
• Limitation is the study was conducted a long time ago and probably conducted in a less scientific environment with less controls. This impacts validity of the research. However, the results of the study have been confirmed by other pieces of research.
• Miller's suggestion


  We can hold 5-9 objects in STM at 1 time. Magic number 7 +- 2.
• Limitation of Miller's research is that it may have overestimated capacity of STM. Cowan reviewed other research and concluded that capacity of STM is 4 chunks. This suggests that 5 items may be more appropriate than 7 items.
• Peterson & Peterson's study

  • 24 students given 3 constants to recall and a 3-digit number to count backwards from
  • Retention interval varied
  • After 3s recall was 80%, after 18s recall was 3%
  • STM duration without recall is 185-30s
• Lack of ecological validity. Same as Baddeley.
• Bahrick's study


  • 392 participants asked to recall classmates' names without pictures and with
  • Recall test - participants listed names of classmates. 60% recall after 15yrs, 30% after 48yrs
  • Recognition test - pictures of classmates from yearbook. 90% accurate after 15yrs, 70% after 48yrs
• High external validity. Meaningful memories studied. When studies with meaningful information were conducted, recall rates were lower. Therefore Bahrick's findings reflect a real estimate of LTM.
• Multi-Store Model (MSM)


  Model of memory with 3 stores: sensory register, short-term memory (STM), and long-term memory (LTM)
• Sensory register


  • All stimuli from the environment pass into the SR
  • Has 5 stores, one for each sense
  • Coding: visual=iconic, acoustic=echoic
  • Duration: half a second
  • Capacity: very high
• STM


  • Limited capacity store of temporary duration
  • Coding: acoustic
  • Duration: 18s unless rehearsed
  • Capacity: 5-9 items
• LTM


  • Permanent memory store
  • Coding: semantic
  • Duration: up to a lifetime
  • Capacity: unlimited
• Strength of MSM is supporting evidence such as Baddeley. His research shows that STM encodes acoustically and LTM encodes semantically. This proves that both stores are separate as they encode differently. However, the material used was artificial so it is unrealistic and therefore lacks validity.
• Limitation is evidence suggesting there is more than 1 STM store. KF had amnesia. His STM recall for digits was poor when he heard them but much better when he read them. Other studies confirm there may be a separate STM for non-verbal sounds. Therefore, MSM is wrong to claim that there is just 1 store.
• Another strength is research support from case studies. HM suffered from epilepsy. He had surgery to relieve this. A part of his hippocampus was removed from both sides of his brain. His LTM was tested again but never improved. His STM was completely fine. He was tested and performed well on immediate recall questions. This suggests that LTM and STM are separate. However, this is a case study so it can't be generalised to the population.
• Working Memory Model (WMM)


  More detailed explanation of short-term memory
• Central Executive


  • Directs attention to particular tasks
  • Controls the other systems by determining how resources will be allocated
  • Has a limited storage capacity
• Episodic Buffer


  • A general store which was added in 2000 to account for things that use both visual and acoustic information
  • A temporary store which links WMM to LTM
• Phonological Loop


  • Deals with auditory information and the order of information
  • Split into 2 components: phonological store and articulatory process
  • Phonological store stores the words we hear, articulatory process allows maintenance rehearsal
• Visuo-Spatial Sketchpad


  • Processes visual and spatial information
  • Subdivided into inner scribe and visual cache
  • Visual cache stores visual data, inner scribe records the arrangement of objects in the visual field
• Strength of Central Executive is supporting research. Bunge did a research study using fMRI scans and found that when participants performed a single task, activity was seen in the CE. When participants were asked to do 2 tasks, dual task additional activity was seen in the CE. This suggests that the CE must exist and performing additional tasks may overload it.
• Strength of WMM is supporting clinical evidence. For example, KF was in a motorcycle accident which resulted in brain damage to his left occipital lobe. His STM was damaged, but LTM was normal. He remembers words better when presented visually then auditory. This supports the view that they are separate visual and acoustic stores. However, the findings of this study cannot be generalised as it is a case study.
• Limitation of the WMM is lack of validity. Dual-task studies support the WMM because they show that there must be separate components. However, these studies are highly controlled and used tasks that are not like everyday tasks. This challenges the ecological validity of the model because it is not certain that WM operates in everyday situations.
• Leading questions


  A leading question is one that suggests certain answer because of the way it is raised
• Response bias explanation


  Wording of the question has no enduring effect on an eyewitness's memory of an event but influences the answer given
• Substitute explanation


  Wording of a question does affect eyewitness memory, it interferes with the original memory, distorting its accuracy
• Loftus & Palmer's study


  • 45 participants watched film clips of car accidents and then answered questions about speed
  • The question used a different verb: 'hit', 'contacted', 'bumped', 'collided' or 'smashed'
  • The verb 'contacted' produced a mean estimate speed of 31.8 mph, 'smashed' produced 40.5 mph
  • The leading question biased eyewitness recall of an event
• Post-event discussion


  Witnesses discussed what they had experienced, affecting the accuracy of their recall
• Memory contamination


  Witnesses mix information from other witnesses with their own memories
• Memory conformity


  Witnesses go along with each other to win social approval because they believe others are right
• Gabbert's study


  • Paired participants watched a video of the same crime but from different points of view
  • Participants discussed what they had seen on the video before individually completing a test of recall
  • 71% of participants mistakenly recalled aspects of the event that they didn't see but had picked up in the discussion
• Strength is real world applications in the criminal justice system. The consequences of inaccurate eyewitness testimony are serious. Loftus argues police officers should be careful in phrasing questions to witnesses because of distorting effects. Psychologists sometimes act as expert witnesses in trials and explain limits of eyewitness testimony to juries. Therefore, psychologists can improve how the legal system works and protect the innocent from faulty convictions based on unreliable eyewitness testimony.
• Limitation of the substitution explanation is evidence challenging it. Sutherland and Hayne found that participants recall central details of an event better than peripheral ones even when asked misleading questions. This is presumably because their attention was focused on the central features and these memories were resistant to misleading information. Therefore, the original memory of the event survived and was not distorted, which is not predicted by the substitution explanation. Another limitation is demanding characteristics. Lab studies give researchers high control over variables so they can demonstrate that misleading post-event information causes inaccurate eyewitness testimony. Lab experiments also suffer from demand characteristics. Therefore, to maximise internal validity researchers should reduce demand characteristics by removing the cues that participants used to work the hypothesis.
• Anxiety


  An unpleasant emotional state where we fear that something bad is about to happen. People often become anxious when they're in stressful situations. This anxiety tends to be accompanied with physiological arousal.
• Johansson and Scott's study


  • Participants sat in a waiting room believing they were going to take part in a lab study
  • Condition 1 - participants heard a casual conversation and then saw a man walking through the waiting room with a pen and grease on his hands
  • Condition 2 - intense argument and the sound of glass breaking. A man walked through the waiting room with a knife covered in blood
  • 49% of participants who had seen the man carrying the pen could identify him, 33% remembered the guy with the knife when shown short pictures of men
• Yuille and Cutshall's study


  • In an actual crime, a gun shop owner shot a thief dead. There were 21 witnesses, 13 agreed to be in this study
  • Participants were interviewed 4 to 5 months after the incident. The information was then compared to police interviews at the time of the incident
  • Witnesses rated how stressed they felt then. Witnesses who reported the highest level of stress were 88% accurate compared to 75% for the less stressed group