Transcript week4
Graham Davies Week 4 Enhancing police interviewing of witnesses Psychology and Police Interviewing • Interviews with witnesses still remain the major source of information in solving crime • Psychologists have been increasingly called upon to refine existing procedures for interviewing both suspects and witnesses • Work on false confessions(Gudjonnson);hypnotic and cognitive interviews Hypnotic Interview (Reiser, 1990) • focussed attention (drawing pin) • relaxation (imagery) • distancing (TV screen) • regression (context induction) • suggestion (perfect recall) Success – The LAPD Study (Reiser, 1980) • 374 ‘dead’ cases • witnesses re-interviewed under hypnosis • 54% new information • 16% cleared up Reiser’s ‘Cybernetic’ Model of Memory • All information is stored • All is potentially available • Hypnotic procedures have no impact on memories “The mind is like a videotape machine, everything is recorded, perhaps at a subconscious level and stored in the brain, but available under hypnosis” (Reiser, 1980) Predictions of Cybernetic Model • More complete recall under hypnosis • Fewer errors • Reduced impact of leading questions and post-event misinformation A facet of the wider debate as to whether hypnosis is an altered state of consciousness. Research on Hypnosis and Memory • No impact on lab tasks (Mingay, 1987; Erdelyi, 1992) • Limited realism? (Yuille & McEwan, 1985) • Confidence and leading questions (Putnam, 1979) But isolated positive findings, particularly with more realistic settings (Yuille & Kim, 1987) Cognitive explanations for positive findings from hypnosis • Impact of cognitive reinstatement instructions (Timm, 1981) • Criterion shift (Dywan & Bowers, 1983) • Hypermnesia (Cooper & London, 1973) Social explanations for positive findings from hypnosis • Compliance and belief (Wagstaff, 1999) • Relaxation and surrendering control (Wagstaff, 1982) Hypnosis: More than the sum of its parts ? • High belief in hypnosis aiding memory (Orne, 1983 - 96%) • High impact on trial outcome (Wagstaff et al., 1992) • People vs Kempinski (1980) • False memory production (Orne, 1979) The Backlash • Hypnotic testimony now banned in 25 States • People v. Shirley (1982) • All three major organisations for hypnotists now ban use with witnesses HOME OFFICE GUIDELINES (1988) • Only qualified personnel • Informed consent • No investigators present • Videotape of whole interview • only when all other methods have failed the impact of R v Browning (1994) The Cognitive Interview • An approach to interviewing grounded in theories of memory function • Simple ideas but widely taken up by the police world-wide • Developed by Geiselman & Fisher (1984) Theoretical Assumptions • Memory as a bundle of features – retrieval involves feature overlap (Bower, 1967) • Memories may be accessed via explicit but multiple pathways. Inappropriate cueing will lead to retrieval failure (Tulving, 1974) Mnemonic techniques of the cognitive interview • feature overlap induced by: - mental reconstruction of environmental/ personal context - report all details instruction • retrieval paths exploited by: - recounting event in different orders - reporting events from a different perspective Plus explicit mnemonics (alphabet searching; resemblance to known person etc.) CI vs ‘Standard’ Police interview and hypnosis (Geiselman et al. 1985) • Police training film of violent crime • Experienced police officers vs CI trained college student interviewers • 40% increase in correct information and no effect on errors • No difference between hypnotic and CI interviews. The enhanced cognitive interview (Fisher & Geiselman, 1992) • Much greater emphasis upon communication skills, less on memory • Rapport building and interviewer support • Witness-compatible questioning • Focused retrieval (imagery) • ‘Perspective change’ and ‘report all details’ de-emphasised Field study on CI Effectiveness (Fisher et al. 1989) Tape recorded interviews by 7 detectives investigating crime ‘on the street’ • Constant interruptions of witnesses • Formulaic interviews • Specific questions After training in the Enhanced CI • Increase in information from 34 – 115% • 94% of ascertainable facts corroborated Later research emphasised the importance of appropriate controls • Earlier studies flawed: number of accounts not controlled • Importance of motivation and n questions • But positive effects still present (Kohnken et al. 1994) Criterion shift or improved accuracy ? • Meta-analysis of published studies (Kohnken et al. 1999) • 35% increase in correct information but only 18% increase in errors from a low base Which components are the most important ? • context reinstatement most reliable • but least used by serving officers (Memon et al. 1995) • children may have difficulties with some components (Saywitz et al. 1995) • Reinstatement may be inadvisable in cases of trauma (Geiselman, 1995)