The Reliability of Eyewitness Testimony
• While human memory is generally accurate, over time it degrades for two main reasons;
information fades over time and memory can be distorted by post event information.
• The reliability of EWT is of huge importance in criminal proceedings, and The Innocence
Project claims that incorrect EWT is the leading cause of wrongful convictions.
• It is therefore vital that we understand how memory works, what can alter it and how we can
prevent this from happening.
• Devlin Committee (1974): Of 347 cases were persecution occurs with only EWT, 74 resulted in
conviction.
• In a court, witnesses are instructed to give only the truth, which suggests there are two
possibilities; lying and not. However, a third possibility is that someone will tell their truth
however what they can remember is not an accurate depiction of what actually happened.
Eyewitnesses are not Reliable
Post Event Information
• Loftus and Palmer (1974): Information from this classic research showed that information
suggested or implied after an event can be incorporated into the memory.
• Loftus and Zanni (1975): 7% of participants asked ‘Did you see a broken headlight?’ Said they
saw one, compared with 17% who were asked ‘Did you see the broken headlight?’.
• The Post Event Information and independent variable was the word A or The.
• The research demonstrates that even subtle changes in the wording used in questions can
influence a participant’s recollection.
• This suggests that a witness’s recollection of an event may be distorted depending on how
they are questioned by their family, friends, police and lawyers.
• People can distort their own memories through self-generation, when the eyewitness can
introduce new information simply by thinking about a robbery.
• Overtime it becomes harder to differentiate between which was actually observed, and
information introduced later on.
• Often the effect of post event information is inconsequential, however, when an eyewitness to
a crime it is important to know exactly what happened.
• The distortion in memory which results from post event information is referred to as the
misinformation effect.
• According to the trace strength theory of suggestibility, if a child is recalling an event that was
experienced several times, he or she would be expected to have a more accurate memory of
the event and be less vulnerable to suggestive influences such as biased interviewing
procedures than if the event had occurred only once.
• This is especially important in child abuse cases because it is common for a perpetrator to
frequently abuse the same child.
• An important constraint on the effect of post event suggestion is that implausible events are
less likely to be suggestively planted in memory than plausible events
Crimes are Emotive Experiences
• Wells, Memon and Penrod (2006): The emotional experience of an eyewitness is one of the
main variables which effect the reliability of eyewitness testimony.
• The central argument is that individuals who witness a negative emotional event will
remember central details but have impaired memory of peripheral details.
• The two working definitions of central are central to the actual scene of a crime, as in the
foreground, and central to the plot of an event thus studies provide varying results of what
people remember.
• Stein and Memon (2006): Descriptions of actions may be recalled to different levels of
completeness and accuracy than person descriptions.
• Eyewitnesses may not be reliable because crimes are so unexpected and potentially
traumatising that memories may be repressed.
• Repression is an idea put forward by Freud and is an Ego Defense Mechanism whereby
threatening memories are pushed into the unconscious mind.
• Today some psychologists call it ‘motivated forgetting’ but either way eyewitness testimony is
not reliable because the crime can have such an emotive effect.
• Research suggests that high stress can seriously impair a person’s ability to identify a
perpetrator even if they were encountered for a considerable amount of time.
• While human memory is generally accurate, over time it degrades for two main reasons;
information fades over time and memory can be distorted by post event information.
• The reliability of EWT is of huge importance in criminal proceedings, and The Innocence
Project claims that incorrect EWT is the leading cause of wrongful convictions.
• It is therefore vital that we understand how memory works, what can alter it and how we can
prevent this from happening.
• Devlin Committee (1974): Of 347 cases were persecution occurs with only EWT, 74 resulted in
conviction.
• In a court, witnesses are instructed to give only the truth, which suggests there are two
possibilities; lying and not. However, a third possibility is that someone will tell their truth
however what they can remember is not an accurate depiction of what actually happened.
Eyewitnesses are not Reliable
Post Event Information
• Loftus and Palmer (1974): Information from this classic research showed that information
suggested or implied after an event can be incorporated into the memory.
• Loftus and Zanni (1975): 7% of participants asked ‘Did you see a broken headlight?’ Said they
saw one, compared with 17% who were asked ‘Did you see the broken headlight?’.
• The Post Event Information and independent variable was the word A or The.
• The research demonstrates that even subtle changes in the wording used in questions can
influence a participant’s recollection.
• This suggests that a witness’s recollection of an event may be distorted depending on how
they are questioned by their family, friends, police and lawyers.
• People can distort their own memories through self-generation, when the eyewitness can
introduce new information simply by thinking about a robbery.
• Overtime it becomes harder to differentiate between which was actually observed, and
information introduced later on.
• Often the effect of post event information is inconsequential, however, when an eyewitness to
a crime it is important to know exactly what happened.
• The distortion in memory which results from post event information is referred to as the
misinformation effect.
• According to the trace strength theory of suggestibility, if a child is recalling an event that was
experienced several times, he or she would be expected to have a more accurate memory of
the event and be less vulnerable to suggestive influences such as biased interviewing
procedures than if the event had occurred only once.
• This is especially important in child abuse cases because it is common for a perpetrator to
frequently abuse the same child.
• An important constraint on the effect of post event suggestion is that implausible events are
less likely to be suggestively planted in memory than plausible events
Crimes are Emotive Experiences
• Wells, Memon and Penrod (2006): The emotional experience of an eyewitness is one of the
main variables which effect the reliability of eyewitness testimony.
• The central argument is that individuals who witness a negative emotional event will
remember central details but have impaired memory of peripheral details.
• The two working definitions of central are central to the actual scene of a crime, as in the
foreground, and central to the plot of an event thus studies provide varying results of what
people remember.
• Stein and Memon (2006): Descriptions of actions may be recalled to different levels of
completeness and accuracy than person descriptions.
• Eyewitnesses may not be reliable because crimes are so unexpected and potentially
traumatising that memories may be repressed.
• Repression is an idea put forward by Freud and is an Ego Defense Mechanism whereby
threatening memories are pushed into the unconscious mind.
• Today some psychologists call it ‘motivated forgetting’ but either way eyewitness testimony is
not reliable because the crime can have such an emotive effect.
• Research suggests that high stress can seriously impair a person’s ability to identify a
perpetrator even if they were encountered for a considerable amount of time.
