The processing of evidence

• Motivating factors of finger print experts:

  • job satisfaction
  • use of skill
  • satisfaction linked to catching criminals and solving crimes
  • solving high profile cases
• Expectation Bias - the expectation of what will be found affects what is actually found

  Confirmation bias - people test hypotheses looking for confirming evidence rather than for potentially conflicting evidence

  Contextual bias - where someone has other information aside from that being considered, which influences the outcome of the consideration
• Dror

  Examined the effect of contextual bias in fingerprint analysis using 27 university student volunteers. 96 pairs of fingerprints were used half were clear and the other half were more ambiguous. There were two emotional states a low one with bike theft and a high one with murder. Results showed in the ambiguous condition 58% were matched in the high emotional context condition compared to 49% in the low emotional context.
• HALL & PLAYER

  Aim- to test if context affected fingerprint identification by fingerprint experts

  Method- An experiment with a volunteer sample of 70 fingerprint experts. There was no time limit and participants were either assigned to the low emotional context or high one. They were then asked if they felt the information on the examination report had affected their analysis.

  Results- 52% of the high context condition said they felt affected compared to only 6% in the low context. The decisions made by the experts were very similar regardless of the emotional context.
• APPLICATION - Independent analysis of the latent and comparison mark (expectation bias)

  Analyse the latent mark from the crime scene separately so the experts aren’t looking for particular features but are analysing the whole print making false accusations less likely.
• APPLICATION - Working in isolation from other evidence (context bias)

  Work in isolation from others and not able to access any crime notes so the expert doesn’t read a high emotional context which influences them to identify a false match in order to get justice.