guest lecture - dr. jessica salerno

psychology and law

confirmation bias

favouring information consistent with your belief

we search for and attend to information that provides evidence for our beliefs

forensic confirmation bias

an individual’s preexisting beliefs, expectations and motives influence the collection, perception and interpretation of evidence during the course of a criminal case

what does confirmation bias affect?

1. collection/search for evidence

2. perception of evidence

3. interpretation of evidence

why was amanda knox a suspect?

mignini only believed that

• women would cover a dead person’s body with a sheet

• knox wasn’t emotional enough

• knox displayed weird/quirky behaviour

collection/search for evidence

mock suspects and interrogators

half of interrogators led to believe that most suspects were guilty

interrogators who expected guilty suspects used more guilt-presumptive questions, worked the hardest to get a confession

perception of evidence

people were motivated to find similarity in handwriting even if there was low similarity

interpretation/use of evidence

adversarial allegiance effect - the tendency of expert witnesses to slant their professional opinions to favour the party that hires them

evidence by judges and juries

seeing gruesome photos in colour influences juries to side with the prosector and ignore defense

perseverance of belief

strong belief despite new information firmly contradicting

motivated skepticism

working hard to disprove info that disagrees with your beliefs

how did all these effects manifest in amanda knox’s case?

once a suspect, always perceived as guilty

forced to elicit false confession

poor collection of evidence

pre-trial publicity

scientifically informed interventions

independent evidence evaluation

blinding experts

videotape every interrogation

education/experts on confessions

independent evidence evaluation

foresic examiners should have NO contextual information and be out of the prosecutors’ offices

blinding experts

evidence line ups

court-appointed experts or blinding to who hired them