Estimating Indetification Accuracy

Confidence - Description

• CJS rely on eyewitness confidence to evaluate the likely guilty of a defendant or suspect

• Jurors are more likely to believe testimony when witness seems confident rather than uncertain – issues with confidence

Confidence and Accuracy

Only useful in limited circumstances

• Witnesses make an identification (opposed to no identification)

  • Choosers have a stronger confidence accuracy relationship

  • Non chooser has a less strong confidence accuracy relationship

• If initial statements of confidence are used (compared to confidence at trail)

• Identification procedure is conducted under pristine conditions

  • If any of these are false then you would be more sceptical of accuracy based on confidence

  • Confidence is not always a good predictor but can be useful only is all these points are true

Confidence - Studies

• Initial studies on witness-confidence accuracy relationship (CA) showed confidence and accuracy were poorly correlated – 1980s

  • Earlier studies focused on point-biserial correlations

• Newer research adopting calibration techniques show strong eyewitness confidence-accuracy relationship for choosers – 2000s

  • 30 different studies and found choosers had a stronger CA correlation when nonchoosers have a very weak correlation

  • Consider the example of a court faced with one witness who has made one identification with 90% confidence.

    • In this scenario, point biserial correlations do little to inform about how likely is the accuracy r value doesn’t inform you much in practice

    • An alternative analytical approach know as calibration

Confidence accuracy calibration

• If the data follows the diagonal line then it would be perfect calibration

• If points deviate from the line then you have some under and over confidence

Calibration analysis

Studies on confidence have shown that higher confident you go it tends to become closer to perfectly calibrated

This suggest that those with higher confidence it doesn’t matter the interval of time they are still rather accurate

Confidence Inflation

Some eyewitnesses may exaggerate or inflate their confidence

• Post identification feedback

• Poor witnessing conditions

• Line up rejections

• When bias lineups or instructions are used

Decision Time

• Faster identification is made the more likely it is to be accurate

• This is a predictor of accuracy in show ups

• The 10-12s rule for accurate identifications

• Lab data from larger number of eyewitnesses showed that there is a larger time range from 5s to 29s

Studies

• Correct identifications tend to be fast but if there is a biased lineup misidentification of similar looking fillers is also fast

• Important limitations for practical use of this is that police don’t routinely assess how fast eyewitnesses are in identifying someone

  • can be tackled by videoing the lineup

Decision Processes

• Accurate witnesses were more likely to show automatic recognition – he popped out to me  

• Inaccurate witnesses were more likely to use process of elimination – I compared the pictures

• Limitation with decision process is that information is unavailable unless is questioned about how they came to that decision

Individual Differences

• Argued that outcome of lineup identifications may partly depend on eyewitnesses ability to recognize unfamiliar faces

  • Performance on face identification test is positively related to eyewitness identification accuracy among choosers

• Lineup Identification test

  • Other studies suggest that individual differences may predispose eyewitness to choose someone from lineup

  • Was found individuals who have higher proclivity to choose in a lineup skills tests are more likely to choose someone from mock witness lineup – checking your response bias

  • Knowing if eyewitness are more incline to choose is important as it can be used to weigh the probative value of suspects identification

Eyewitness Metamemory

Metamemory

• Knowledge and awareness that an individual has about their own memory capabilities

• In terms of eyewitness its about their ability to recognise faces, remember faces

• Found that the more discontent people are with their ability to recognise faces the more they will make inaccurate identification

Eyewitness Issues

• Some memory issues aren’t common sense to investigators who collect the identification evidence

• Judges, juries and others in trials are often unaware of issues related to eyewitness evidence

Expert and General Knowledge

Met-analysis on eyewitness issues

• Results reveal that there are several factors for which lay knowledge is inadequate.

  • Agreed

    • Question wording

    • Alcohol intoxication

    • Attitude and expectation

  • Disagree

    • Hypnotic suggestibility

Judges Knowledge

• USA

  • Wise and safer 2004 – 160 US judges

  • Judges were often wrong on important issues

  • 80% or more of judges gave correct response for only three of the 14 eyewitness statements

• Norway

  • 80% or more of the judges giving the correct response for only five of the 15 eyewitness statements.

• Benton et al 2006

  • Jurors disagreed with experts on 87% of the issues

  • Judges and law enforcement disagreed with experts on 60% of the issues

  • “the legal system may benefit from expert assistance in the evaluation of eyewitness evidence.”

Expert Testimony

• Research that has been done provides the idea that it may not be very helpful

• Can cause jurors to become overly sceptical of eyewitness evidence

  • Leippe et al 2004

    • Expert testimony decreased perceptions of guilt and eyewitness believability

  • Martire & Kemp 2011

    • Reviewed 24 experiments

    • Only one experiment provides evidence that expert testimony can improve jurors’ ability to discriminate between accurate and inaccurate eyewitness identifications

Judicial Instructions

Biggers Criteria

• 1972 Court outlined five criteria that should be used in evaluating the accuracy of eyewitness identifications

  • witness's certainty

  • his or her quality of view

  • amount of attention paid to the culprit

  • agreement between the witness's description and the suspect

  • amount of time between the crime and the identification attempt

Henderson Instructions

• New instructions addressing case-specific factors must be presented to the jury

Jones et al

• Both Henderson instructions and expert testimony were not effective in assisting jurors to evaluate eyewitness evidence

• Instructions lead to sceptics rather than being able to determine what is strong and what is weak evidence

Teaching aids

I-I-EYE

• PowerPoint presentation

  • 1) the eyewitness interview procedures were conducted properly

  • 2) the identification procedures were conducted properly

  • 3) there were any factors present during the crime that might have negatively affected the eyewitness memory

• Compared to participants receiving general information about the trial process or the Biggers criteria, those who received the I-I-Eye teaching aid demonstrated increased sensitivity