Year 12 Haze Cover Work Psychology

Transcription

1 Year 12 Haze Cover Work Psychology 1. Students to read through the Mann et al. (2002) study in their Cambridge books using the core studies booklet that was handed to them at the beginning of the unit students should summarise the study in their own words. 2. Students must evaluate the study based on the evaluation techniques that we have looked at over the last two weeks. 3. Student should then write a reflection on how the findings from Mann et al. (2002) are applicable to everyday life.

2 Suspects, Samantha Mann, Aldert Vrij and Ray Bull (2002) SUSPECTS, LIES AND VIDEOTAPE: AN ANALYSIS OF AUTHENTIC HIGH STAKE LIARS

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4 WHAT TO LOOK FOR IN A LIAR People believe that liars fidget more and avoid eye contact In reality, most people move less and become quite still, and there is no relationship at all between eye contact and lying. Most data obtained via laboratory experiments where subjects are asked to lie/tell the truth about their opinions, personal details, films they have just seen etc etc hence problems with ecological validity in these studies.

5 PROBLEMS WITH SUCH STUDIES Subjects need feel no guilt Subjects will be aware that they are being closely observed and/or videotaped Lies that are told may be of minimal consequence saying you support Manchester United rather than Chelsea... or is that of consequence?

6 SO THIS STUDY... Studies real suspects in police custody. High stake the costs of losing a bet or being found telling a lie are high the person has a lot to lose. High stakes for 4 out of 16 suspects conviction would mean life sentences. The effort required to create convincing lies inhibits other movements, including eye-blinking; and increases speech errors and delays in response to questions. Liars are aware of the stereotypes (fidgeting and eye contact) and can overcompensate, often becoming rigid and maintaining too much eye contact. Even in high stake situations, then, liars do not necessarily show an increase in nervous behaviour.

7 SO IS THERE A UNIVERSAL INDICATOR OF LYING? Probably not. The authors do not expect to find a predictor of deception to be found which overrides all the individual differences in deceptive behaviour.

8 PARTICIPANTS 16 police suspects (13 male, 3 female). Four were juveniles (three 13 year old and one 15 year old) and all others were adults. 15 caucasians and 1 asian (Punjabi) Theft (9), arson (2), attempted rape (1) and murder (4). Majority were well known to the police and had been interviewed before.

9 PROCEDURE Kent police force, UK Detectives asked to identify videotaped interviews in which suspect lied at one point and then told the truth at the other. Case files then collected and experimenter checked details to find forensic or other evidence which supported the truth or dishonesty of the suspect. Sections of videos where these criteria were made were edited to make a one-hour long video involving 16 suspects.

10 PROCEDURE 2 Total of 65 clips: 27 truths and 38 lies For each participant there was a minimum of two clips (one truth and one lie) and a maximum of eight clips (no less than three truths and no more than 5 lies) Length of clip varied between 5 to 145 seconds, though authors are confident length of clip does not affect the measurement of the behaviour.

11 DEPENDENT VARIABLES Two observers independently coded the eight behaviours (one saw all of them, the other saw a random sample of 36 clips) This was to limit the exposure to the video footage as much as possible for ethical reasons. Coders were blind to whether or not the clips were truth or a lie.

12 THEY LOOKED FOR 8 CATEGORIES Gaze aversion Blinking frequency Head movements Head shakes, head nods, other movements Self manipulations Scratching the head, wrists etc Illustrators hand movements involving arms to exaggerate a point Hand/finger movements (ie not involving arms) Speech disturbances Ah, mmm, repetition, sentence incompletion etc Pauses

13 RESULTS Observations were transformed into figures so that truth telling and lies could be directly compared: Quantitative data. Length of time per minute spent in pauses, or gaze aversion. Frequency of blinks, head and arm/hand movements per minute. Number of speech disturbances calculated for each participant per 100 words.

14 RESULTS Behaviour Gaze aversion Blinks Head movements Hand/arm movements Pauses Speech disturbances Truth ** * 5.22 Lies Truth Lies

15 RESULTS As predicted, there was no behaviour that all liars exhibited. For example, 56% showed more gaze aversion and 44% showed less; 50 % showed more head movements and 50% showed less. The most reliable indicators of deception were blinking and pauses, where the majority of participants paused longer (81%) and blinked less (81%) when lying.

16 DISCUSSION One of the very few to examine real-life high-stake setting. Suggest that the factors of less blinking and longer pauses represent the cognitive load of lying. Remember that the study did not measure or manipulate cognitive load, so these findings are speculative. The finding that there is no typical deceptive behaviour, and individual differences play a large part.

17 PROBLEMS Different interviewers used for different videos Sometimes more than one interviewer was present Total number of people present varied They did not compare the behaviour of high-stake liars with high stake truth-tellers those genuinely denying an offence they did not commit. Is 16 suspects enough? Authors suggest that limited availability of suitable tapes and time constraints for both police and authors was a problem.

18 ECOLOGICAL VALIDITY ETC Think about this study in terms of ecological validity. How true to life do you think it is.? How real were the measurements they obtained, bearing in mind that not all interviews were the same length, and that some measures (hand movements per minute) are biased depending upon the length of the video clip.

19 THINK USEFULNESS How useful would it be to police officers, lawyers and judges to be able to diagnose truth telling or lies?