"Eyewitness memories are not as reliable as they are generally thought to be"
Reliability
Memory manipulation
Eyewitness Testimony
- Juries highly value eyewitness testimony
Has been used for several decades in law enforcement
Definitions
Testimony: A written or spoken statement, typically referring to a type of evidence used in a court of law
Eyewitness: A person who has seen something and can / does give a first-hand description of it
Lofthus study
18% found the defendant guilty with circumstantial evidence
72% found guilty with same evidence + an eyewitness
- Accounts for approx. 50% of wrongful convictions
Being trustworthy
Natural memory change
The human brain and memory is believed to record and store all information accurately and without change
Disproven in many studies
People believe memories are accurately 'played back'
In fact memories are repeatedly reconstructed
Uses pre-existing and new information
Memory retrieval
Memory accuracy and quantity decline over time
- 9/11 Memory study
References
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After one year: 77% accurate
The misinformation effect
Leading questions
Questions which include presumptions about the incident
During reconstruction, the memory uses new information, including presumed information from questions
E.g. "When the car crashed" implies the car was going fast, and there was a major accident, even if it was merely a light tap
During reconstruction, the memory uses new information, where misinformation can then be used to 'edit' the recollection
Encoding memory
STM
Memory is better encoded with stronger emotions
Lasts for 20seconds
Disappears without rehearsal
7 +- 2 pieces of information at a time
If working memory used at the same time, the STM is already dealing with multiple pieces of information
Can emotion enhance or stifle memory?
If a witness's attention is on a for example a gun, then their memory of the face behind the gun may be limited
Interference from other memories
Retroactive interference
New information interferes with the recalling old information
Events after the crime can interfere with remembering the crime
After one week: 88% accuracy
Retrieval cues
Context-dependent cues
Cues present in the encoding environment which assist in the retrieval of the memory, e.g. forgetting what you came for when you go to another room, then remembering when you return
State-dependent cues
Cues associated with the psychological and physiological state during encoding, e.g. remembering other memories associated with hunger when you feel hungry
Memory Storage
The brain requires time to consolidate any new information
Memories can be disrupted at this time
At least 30min of 'drying' for the memory
This is required for new connections to be physically built between information in the LTM
This creates 'memory traces'
These traces decay without reactivation and usage
A physical / chemical change representing stored information
Using definitive articles, e.g. "broken headlights" vs "the broken headlights"