Memory key studies

• Aim - to see how information is stored in STM and LTM. 
• Procedure - groups were given word lists and had to recall in the correct order.
  • Group 1 - given acoustically similar words. 
  • Group 2 - given acoustically dissimilar words. 
  • Group 3 - given semantically simliar words.
  • Group 4 - given semantically dissimilar words.
• Findings
  • 1 and 2 - when words were recalled immediately, group 1 performed worse (Similar sounding words)
  • 3 and 4 - when words recalled after 20 minutes, group 3 performed worse (words with similar meanings)
• Conclusion - STM has acoustic coding, LTM has semantic coding. 

• Aim - to see how much information the STM can hold at one time. 
  
• Procedure - researcher read 4 digits, and the participant must repeat them back in the same order. If correct, length of digits increases by 1 each time. This procedure was repeated for letters. 
  
• Findings - on average, participants could remember 9.3 numbers, and 7.3 letters. 
  
• Conclusion - the capacity of the short term memory lies between 7 and 9 on average. 

Miller 

• Found that many things come in groups of 7, and that people can recall 5 words as well as they can recall 5 letters. 
  
• Concluded that capacity of STM was 7 ± 2 items. 

• Aim - to see how long information is held in the short term memory. 
  
• Sample - 24 student participants. 
  
• Procedure - each participant was given a trigram (eg. CMV) to remember. they then counted backwards from a given number in intervals to prevent mental rehearsal. The participants repeated the trigram. 
  
• Findings - after 3 seconds, average recall was 80%, but after 18 seconds it was just 3%. 
  
• Conclusion - the duration of short term memory is a maximum of 18 seconds, unless mental rehearsal takes place.  

• Aim - to see how long information can be held in the LTM. 
• Sample - 392 Americans between 17 and 74 years old. 
  
• Procedure 
  • Photo recognition - asked to identify the person in images, including members of their class in high school. 
  • Free recall of names - had to recall names of all members of their graduating class with no prompts. 
• Findings
  • Photos - those who graduated 15 or less years ago were 90% accurate. After 48 years, recall was 70%
  • Names - those who graduated 15 or less years ago were 60% accurate. After 48 years, recall was 30%.
• Conclusion - duration is a lifetime for some items.  

• Aim - to see why we forget
• Procedure - all participants were given the same set of words to start, but were given an additional list as followed:
  • 1 - similar meanings as originals
  • 2 - opposite meanings to originals
  • 3 - words unrelated to originals 
  • 4 - consonant syllables 
  • 5 - three digit numbers
  • 6 - no new list 
• Findings - the group with the worst recall was group 1, which had the words which were similar in meaning to the original list. 
  
• Conclusion - interference is strongest when memories are similar. 

• Sample - deep sea divers 
• Aim - to see whether training on land hindered or helped their underwater work
• Procedure - divers were given a list of words to learn but learned and recalled in differing conditions:
  • Group 1 - learn on land, recall on land
  • Group 2 - learn on land, recall underwater
  • Group 3 - learn underwater, recall on land 
  • Group 4 - learn underwater, recall underwater 
• Findings - recall was higher in matching learning and recall conditions. Recall was 40% lower when the contexts differed. 
  
• Conclusion - absence of external cues at learning and recall cause retrieval failure. 

• Aim - to see if difference in individual state affects memory.
• Procedure - participants given list of words or sections of writing to remember. The personal states differed as follows:
  • Group 1 - learn on drug, recall on drug
  • Group 2 - learn on drug, recall off drug
  • Group 3 - learn off drug, recall on drug
  • Group 4 - learn off drug, recall off drug
  • The drug used was an antihistamine to treat hayfever, but caused drowsiness in users.  
• Findings - a mismatch in internal state between learning and recall caused poor results.
• Conclusion - absence of internal cues at learning and recall cause retrieval failure. 

• Aim - to see whether the use of a leading question influences answers. 
  
• Sample - 45 students 
• Procedure - participants watched a video clip of a car crash. Asked how fast the cars were going when they '__________'. the verb used to describe the crash changed.
• Findings - the verb used had an influence on the speed given. 
  
  • contacted - 31.8 mph
  • hit - 34.0 mph
  • bumped - 38.1 mph
  • collided - 39.3 mph
  • smashed - 40.5 mph
• Conclusion - leading questions negatively effect quality of EWT. 

• Procedure - same as baseline. Participants were asked if they saw broken glass at the scene of the crash (there was none)
• Findings - participants who had "smashed" as their variable were more likely to report broken glass at the scene, despite not seeing any. 
  
• Conclusion - leading questions can also affect memory of the incident. participants asked leading questions are likely to admit seeing something they didn't. 

• Aim - to see whether discussion with others causes misinformation 
• Procedure - participants were paired and watched the same video from two different perspectives. they could see things the other could not. They discussed what they had seen in the video and completed a questionnaire. 
  
• Findings - 71% of participants recalled aspects of the crime they did not see in their video but had learned through discussion. The control group (no discussion) has 0% incorrect recall. 
  
• Conclusion
  • memory conformity - change their ideas as they think they are wrong and the other witness is correct. 
  • memory contamination - discussion with others distort ones memories of the event. 

• Aim - to see if anxiety affects the validity of EWT. 
• Procedure - participants believed they were participating in a lab study, and whilst waiting they heard either a casual chat (1) or an argument (2) then saw a man with 1) a pen and greasy hands, or 2) a knife and bloody hands.
• Findings - when asked to identify the man from a series of 50 photos, 49% of pen group (1) could identify the man. Only 33% of knife group (2) could identify the man. 
  
• Conclusion - weapons focus has an impact on the second group's memory - where an individual focuses too heavily on the weapon in a crime and subsequently cannot remember other details. 

• Aim - to see if anxiety has a positive effect on recall.
• Sample - 13 witnesses to a shooting
• Procedure - witnesses were interviewed 4 to 5 months after the shooting took place and answers were compared to official police reports from the time of the shooting.
• Findings - witnesses remained extremely accurate in their answers and while some details such as age and height were slightly different, they averagely remained similar. 
  
• Conclusion - Anxiety does not have a detrimental effect on EWT accuracy and may enhance it. 

The process of the cognitive interview 

• Report everything - witnesses should say everything they remember from the event, even if they don't think it is important. 
• Reinstate the context - return to the crime scene mentally and imagine the environment (linked to CDF)

• Reverse the order - change the order in which events occurred (e,g, work backwards from the final event)

• Change perspective - think about the event from the stance of another person, and think what they saw or heard.