The Houses of Parliament have produced a note on Unintentional Bias in Court which deals with the issue of how assumptions, stereotypes and “contextual information” can influence judgement unintentionally. The note concentrates upon the impact in criminal proceedings. However it is worthwhile looking at the research in relation to “witness certainty”.
Above all, it is important to avoid the fallacy of supposing that, because a witness has confidence in his or her recollection and is honest, evidence based on that recollection provides any reliable guide to the truth.”
THE HOUSES OF PARLIAMENT PAPER
“Witness confidence and certainty
Some factors can make a witness more certain that an event occurred without making it more likely that it did. Further, people may interpret a display of confidence as an indication of accuracy, even though it does not necessarily increase the likelihood that a witness is accurate.
Factors which increase witness certainty
A Dutch study showed that peoples’ certainty in a recollection increases the more they retell the story, which may be relevant when eyewitnesses give multiple interviews. Furthermore, US research shows that hearing feedback that corroborates a claim raises mock witnesses’ certainty in the claim, even when feedback is misguided.Post-identification feedback affects real UK witnesses: telling them if they did or did not pick the suspect affects how difficult they think the identification task was.
Juror interpretations of witness confidence
A display of confidence by a witness might reinforce jurors’ beliefs that a witness is accurate whether or not they are. In a US study, participants who read a transcript written by an eyewitness displaying high confidence subsequently remembered the eyewitness as having had a better view of the event than participants who read a transcript from an eyewitness displaying low confidence. In another US study where an eyewitness displayed greater confidence in court than in their original statement, mock jurors only reduced their estimation of the eyewitness’ accuracy if the eyewitness was explicitly challenged about the inflation of confidence during cross-examination.”
CREDIBILITY IN THE CIVIL COURTS: COMPARISON WITH THE GUIDANCE IN GESTMIN
Many of these issues have been recognised by the civil courts. We have looked several times before at the guidance given in the judgment of Mr Justice Leggatt in Gestmin SGPS S.A. -v- Credit Suisse  EWCA 3560 (Comm). The central issues that the confidence of a witness is not, in itself, a good indicator of accuracy is recognised and set out.
THE KEY MATTER: CONFIDENCE AND HONESTY DOES NOT AMOUNT TO ACCURACY
“Above all, it is important to avoid the fallacy of supposing that, because a witness has confidence in his or her recollection and is honest, evidence based on that recollection provides any reliable guide to the truth.””
POINT BY POINT: THE GUIDANCE IN GESTMIN ON ASSESSING WITNESS EVIDENCE
- There obvious difficulty with allegations and oral evidence based on recollection of events which occurred several years ago is human memory.
HUMAN MEMORY IS FALLIBLE
- Everyone knows human memory is fallible.
- The legal system has not sufficiently absorbed the research into the nature of memory and the unreliability of eyewitness testimony.
- We are not aware of the extent to which our own memories are unreliable and believe our memories to be more faithful than they are.
COMMON MISCONCEPTIONS WITH MEMORY
Two common and related errors are that:
- The stronger and more vivid is our feeling or experience of recollection the more likely the recollection is to be accurate.
- The more confident another person is in their recollection, the more likely their recollection is to be accurate.
THE FAULTY MODEL OF MEMORY AS A MENTAL RECORD
Underlying both these errors is a faulty model of memory as a mental record which is fixed at the time of the event and fades over time.
- Memories are fluid and malleable.
- They are constantly rewritten whenever they are retrieved.
- This is true of “flashbulb” memories of a shocking or traumatic event.
- The very description “flashbulb” memories is misleading because it reflects the misconception that memory is like a camera.
- External information can intrude into a witness’s memory as can their own thoughts and beliefs.
- This can cause dramatic changes in recollection.
- Events can be recalled as memories which did not happen at all or which happened to someone else (“a failure of a source of memory”.
MEMORY IS ESPECIALLY UNRELIABLE WHEN IT COMES TO RECALLING PAST BELIEFS
Memory is unreliable when it comes to past beliefs.
- Memories are revised to make them more consistent with our present beliefs.
- Studies show that memory is particularly vulnerable to inference and alteration when a person is presented with new information or suggestions when their memory is already weak due to passage of time.
THE PROCESS OF CIVIL LITIGATION ITSELF SUBJECTS MEMORY TO BIASES
The process of civil litigation itself subjects the memories of witnesses to powerful biases.
- Witnesses have a stake in a particular version of events.
- This is more obvious in relation to parties and those with ties of loyalty to parties.
- More subtle influences include the very process of making a witness statement and going to court to give evidence.
- A desire to assist the party calling a witness and a natural desire to make a good impression can be significant motivating factors.
THE PROCEDURE OF PREPARING FOR TRIAL HAS A CONSIDERABLE INTERFERENCE WITH MEMORY
Considerable interference with memory is introduced by the process of preparing for trial.
- A witness is often asked to make a statement a long time after the relevant events.
- The statement is usually drafted by a lawyer who is lawyer who is conscious of the significance of the issues in the case.
- The statement is made after a witness’s memory has been “refreshed” by reading documents.
- The documents include pleadings and other argumentative material which the witness did not see at the time or which came into existence after the event.
- The statement goes through several versions before it is finalised.
- Months later the witness is asked to re-read the statement and documents before giving evidence in court.
- The effect of this is to establish in the mind of the witness the matters in the statement and documents whether they be true or false.
- This also causes the witness’s memory to be based increasingly on the material and later interpretations rather than the original events.
THE DIFFERENCE BETWEEN RECONSTRUCTION AND RECOLLECTION
Witnesses are often asked in cross-examination the difference between reconstruction and recollection.
- These questions are misguided.
- There is a presumption that there is a clear distinction between recollection and reconstruction.
- All remembering of distant events involves reconstruction processes.
- Such questions disregard the fact that such processes are largely unconscious and that the strength, vividness and apparent authenticity of memories is not a reliable measure of their truth.
THE APPROACH OF THE JUDGE
Mr Justice Legatt was particularly concerned with commercial cases. However, again, these matters are probably universal.
- A judge places little, if any, reliance on witnesses’ recollections of what was said in meeting and conversations.
- Factual findings are based on inferences drawn from the documentary evidence and known probable facts.
THIS DOES NOT MEAN THAT ORAL EVIDENCE SERVES NO USEFUL PURPOSE
- The utility of witness evidence is often disproportionate to its length.
- Its value largely lies in the opportunity which cross-examination affords to subject the documentary record to critical scrutiny and to gauge the personality, motivations and working practices of a witness rather than what the witness recalls of particulars conversations and events.