Interviewing witnesses

Recognising faces - Bruce

Factors influencing identification - Loftus

the cognitive interview- Fisher

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  • Created by: Amy Leech
  • Created on: 20-03-13 08:58

Bruce; internal and external features in facial re

Background: Familiar faces are more relaibly recognised than unfamiliar, regardless of identification conditions (e.g. lighting).

Experiment 1; Aim: To investigate the relative recognisability of internal ( eyes, nose, mouth, brows) and external (head shape, hair, ears) features. Sample: 30 staff and students; Stirling university, paid £2 to sort composites, gender balanced, aged 18-60 (mean age 29). Method: Lab experiement (independant measures). Set of 10 composite/target celebrity colour photos; participants tested individually; randomly assigned to one of three composites (whole/face head), internal or external features). Task: to view the composites produced using different UK/US systems used by police, e.g. E-FIT, PRO-fit, FACES, sketch) then match them to photos.

Experiement 2; Aim: Photo array task to compare quality of external and internal composite features of first experiment (task intended to be similar to police line up identification process). Sample: 48 undergraduate volunteers, Stirling University; 21 males, 27 females; aged 18-31 (mean age 21). Method: Lab experiment. Participants tested individually; randomly assigned to one of four testing books (easy internal or external features; hard internal or external features). Task: view set of famous- face composites, then pick them out from photo line-up, comprising one celebrity and five distracter faces (foils).

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Bruce; internal and external features in facial re

Results: Experiment 1: Whole and external composites sorted 33% correct, while internal composites only 95% correct (10% correct by chance). Experiment 2: Composites of external features were identified better (42% correct) than internal features (28% correct). Performance better on E-FITS (40% correct identification) than PRO-fits (30% correct).

Evaluation: Wide age range means participants familiarity with celebrities would vary. Expectation that greater familiarity would improve sorting; however, mean sorting scores did not change with familiarity for complete and internal features (only marginal differences for external). Small samples not reliable. A typical participants so cannot generalise findings. Good control/standardisation. Lab setting  lacks ecological validity; however, photo array is similar to line-up procedure and witnesses often required to look at photos as part of identification process. Very useful to inform police/courts about lack of reliability of witness identification. Psychology as science - standardisation/controls, meets criteria (replicability, falsifiability, objectivity).

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Loftus; Weapon focus

Background: Weapon focus refers to the concentration of a crime witness' attention on a weapon and the reduced ability to remember other crime details.

Aim: To investigate and assess evidence for weapon focus.

Experiment 1: Sample: 36 students, Washington University; aged 18-31. Method: Lab experiement (independant measures). Participants viewed a series of 18 slides (people in a queue for restaurant cashier). Controls saw 'person B' holding a cheque, while 'weapon' condition saw 'person B' pulling a gun (both stimuli appeared in four slides). Eye movements recorded with a corneal reflection device. A 15 min retention interval was followed by a 20 min item, multiple-choice questionnaire (four response choices), including seven items about 'person B', e.g. 'what was the colour of B's coat?' Next, given a 'line-up' of 12 photos to test identification of 'person B'.

Experiment 2: Sample: 80 psychology students, Washington University (participating for extra credits). Method: Lab experiment, 40 in control condition (cheque), 40 in weapon condition; same slide presentation as experiment 1. After 15 minute retention interval, participants given a seven item multiple choice test of items relating to 'person B', followed by 'line up' identification test of 12 photos.

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Loftus; Weapon focus

Results: Experiment 1: No significant difference found between conditions in accuracy of questionnaire responses overall, or on seven items relating to person B (although weapon condition slightly less accurate than control). Eye movement data: significant difference found with more eye fixations (with longer duration) in weapon condition than control. 'Line-up' data analysis: controls identification slightly more accurate than weapon condition (marginally significant). Experiment 2: Questionnaire responses and line-up data analysis revealed weapon condition participants significantly less accurate than control (5% level).

Evaluation: Findings provide support for weapon focus; however, authors speculate that similar results might be found with highly unusual objects. The second study has more reliable sample size. Good control/standardisation means higher confidence in results. Lacks ecological validity (viewing slides), but could argue lack of stress (weapons condition) ethically sound. It has important implications for reliability of eyewitness identification and memory. Reductionist - doesn't take into account individual differences. Psychology as a science - standardisation/ controls, recording of eye movements, etc, meets criteria of replicability, falsifiability and objectivity.

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Fisher; Field test of the cognitive interview tech

Background/Aim: To investigate the effectiveness of the CIT (in enhancing recall in victims and witnesses) in a field experiment.

Sample: 16 experienced detectives from the Robbery Division, Florida Police Department (minimum of 5 years with robbery division). 

Method:Preliminary phase (took four months to complete). Detectives tape-recorded interviews, using standard interviewing procedures. From amount of information gathered and recommendations of detectives' commanding officer, 2 groups formed: one trained in use of CIT (10); remainder untrained control group (6). Training conducted in four one hour group sessions, followed by tape-recorded, practice interview in the field (feedback received). (three in trained group did not complete the full training programme due to changing schedules, court appearences, etc.)  Post training phase: (took seven months to complete): seven trained and six controls tape-recorded 2-7 clases each, total of 47 interviews recorded (24 by trained, 23 by untrained/controls) As in preliminary phase, these interviews were mainly victims of commercial robbery/purse snatching. Tape transcriptions and counting number of relevant, objective statements (e.g. physical descriptions of assailant, clothing, weapons etc.) completed by two different groups of research assisstants who were blind to condition of interviewer.

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Fisher; Field test of the cognitive interview tech

Results: Mean number of facts elicited per interview by detectives; 

                    Pre training phase                       Post training phase

Trained               26.8                                              39.5

Controls             23.7                                              24.2

As a group the seven trained detectives elicited 47% more information after training compared to before training, with no loss of accuracy (improvement ranged from 34-115%) (one detective did not improve: analysis of post-training interviews showed he did not use CIT recommended techniques.)

Evaluation: Limitations means the results cannot be generalised - a) very small sample is unreliable; b) data based on restricted crime type; c) detectives experienced in robbery; d) geographically specific. Nurture- techniques can be learned. Usefulness- CIT is effective in improving information retrieval from witnesses/victims; training is effective.

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