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34 Cards in this Set
- Front
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Describe behaviours recorded by observers from the videotapes (Mann Et Al.) |
Gaze aversion: number of seconds for which the participant looked away from the interviewer Blinking: frequency of eye blinks NB: blink more / blink less = 2 marks (as indicate that frequency was measured) Head movements: frequency of head nods (upward and downward movement was counted as a separate nod), head shakes (similar to head nods, each sideways movement was counted as a separate shake) and other head movements that were not included as head shakes or head nods (eg tilting the head to the side, turning the face etc.) Self-manipulations: frequency of scratching of the head, wrists etc. (touching the hands was counted as hand/finger movements rather than self-manipulations) Illustrators: frequency of arm and hand movements which were designed to modify and/or supplement what was being said verbally Hand/finger movements: any other movements of the hands or fingers without moving the arms Speech disturbances: (they were scored on the basis of typed verbatim text) frequency of saying “ah” or “mmm” etc. between words, frequency of word and/or sentence repetition, sentence change, sentence incompletion, stutters etc. Pauses: Number of seconds where there is a noticeable pause in the monologue of the participant, when the suspect actually stops between words for a period of approx 0.5s or more, stopping the free-flow of conversation for a period of time whilst the suspect thinks of the next word. |
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Describe individual differences in deceptive behaviour (Mann Et Al.) |
head movements – 50% increased when lying, 50% decreased when lying speech disturbances – 50% increased when lying, 50% decreased when lying gaze aversion – 56% increased when lying, 44% decreased when lying blinking – 81% decreased when lying pauses – 81% increased when lying Could also quote results from other studies reported by MVB:hand/arm movements – 69% decreased when lying, 31% increased when lying |
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Explain why Mann et al challenged the simplistic view that typical deceptive behaviour exists.(Mann Et Al.) |
“Importantly, the findings of this study demonstrated large individual differences in deceptive behaviour and they challenge the simplistic view, even expressed by professional lie- catchers that a typical deceptive behaviour exists.” |
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Explain why this is an experiment. (Mann Et Al.) |
has IV and DV IV (of lying or telling the truth) is manipulated DV (of gaze aversion, blinking etc.) is measured comparison between groups (lying or telling the truth) / looking for differences (between lying or telling the truth) investigates causal relationships (lying affects behaviour) controls employed (coders unaware of reason for coding) |
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Outline one advantage of laboratory experiments using this study as an example (Mann Et Al.) |
controls employed: coders unaware of reason for coding can manipulate IV: e.g. correctly select truth / lie segments of video |
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Aims of study(Mann Et Al.) |
to investigate whether there are systematic differences in behaviour between lying and truth- telling; to investigate individual differences in behaviour during lying and truth-telling; to investigate real-life lying (of criminal); to investigate lying in high-stake settings (suspected of murder); to extend the work of Vrij and Mann (2001). |
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Explain why it is hard to investigate the nonverbal behaviours accompanying deception.(Mann Et Al.) |
“because it is difficult to capture on tape people lying spontaneously where it is known for certain that they are lying, and at which point” difficult to judge, observer bias more likely e.g. “It’s hard to know if they’re lying; and there would be demand characteristics in a lab study” |
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How did they overcome the problem of investigating the nonverbal behaviours accompanying deception.(Mann Et Al.) |
They examined: videotapes of real criminals being questioned by police, using suspects who initially denied but later confessed to high stakes crimes, and studied videotapes of truthful and deceptive behaviour |
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Previous laboratory studies have been on lie detecting. How are they unreliable?(Mann Et Al.) |
1. because the participant has been asked to lie, s\he need feel no guilt about deceiving the target 2. participant will most likely be videotaped and will be aware that this is entirely for the purpose of enabling art least one person who knows when s\he is lying or telling the truth 3. previous research is generally based on participants telling lies of negligible consequence. Although researchers can offer monetary or other rewards to encourage a convincing impression from the liar they cannot ethically offer a substantial punishment as motivation. |
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Describe sample(Mann Et Al.) |
16 police suspects (13 males and 3 females) Four were juveniles (3 were aged13, one was 15) 15 caucasian 1 asian (first language punjabi) who spoke fluent english Majority of participant ( out of 16) were well known to the police and had been interviewed relating to previously committed offenses |
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Crimes of suspects(Mann Et Al.) |
Theft = 9 Arson = 2 Attempted rape = 1 Murder = 4 |
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How were the videotapes collected and what were they based on (Mann Et Al.) |
Police detectives were asked if they could recollect videotaped interview in which they were involved where the suspect had lied at one point and told the truth at another. Once they were collected the experimenter scoured the files looking for forensic evidence of substantial reliable independent witness statements to corroborate instances of truth or lie as implicated by the investigating officer. An example of such an appropriate case would be where the suspect initially denies any involvement in the crime and then confess after being presented with substantial forensic/witness evidence. cases without such evidence were eliminated |
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Describe videotape (Mann Et Al.) |
hour long consisting of clips from 16 suspects. the truths that were selected were chosen so as to be as comparable as possible in nature to the lies 65 clips. Truths = 27. Lies=38 For each participant there was a minimum of 2 clips and a maximum of 8 clips of which no less than 3 clips were truths and no more than 5 clips were lies. Total length of clips per participant ranged from 41.4 to 368.4s. |
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Who coded the behaviors?(Mann Et Al.) |
Two observers Independently coded the 8 behaviours They were not informed about the hypotheses and nature of the video clips. They were not informed if the suspects were lying or telling the truth. Coder 1 coded all clips and coder 2 coded a random sample of 36 clips (clips from each of the 16 suspects) |
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How were similarities checked between the coders (Mann Et Al.) |
A pearson’s correlations was conduct between the two sets of data from the two coders to assess similarities in judgement. |
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Why not both coders code all the clips? (Mann Et Al.) |
“Given the sensitivity of the video footage it was desirable that as few people outside the police as possible would be shown the tapes, therefore we decided to let the second coder code a sample of the clips first and perform coder reliability checks on this sample” |
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What were the different tests that were made and what did the result show?(Mann Et Al.) |
t tests were used to test the average differences between the 2 coders did not differ none of these t tests were significant |
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How was Data analyzed?(Mann Et Al.) |
Data were analyzed utilizing a MANOVA with veracity (truth/lie) as the only (within-subjects) factor and the six behaviors (gaze aversion, blinks, head movements, hand\arm movements, pauses, speech disturbances) as dependent variable. At a multivariate level, the analysis was significant. F(6,10) = 3.42. |
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Why do some liars do not show nervous behaviour? (Mann Et Al.) |
Liars may not exhibit nervous behaviours because they are probably simultaneously experiencing other processes particularly increased cognitive load and/or attempted behavioural control, which will negate their nervous behaviours. |
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Why did the experimenters predict that the participants will exhibit cognitive load?(Mann Et Al.) |
First, the liars will probably have to think hard in order to make their lies convincing because a contradiction in the story could lead to a conviction. Evidence has demonstrated that people engaging in cognitively complex tasks make fever movements such as fewer illustrators, self manipulations, and other subtle hand movements, and suggests that increased cognitive load results in a neglect of body language, reducing overall animation. Increased cognitive load can result in increased speech disturbances and longer pauses before giving an answer. It has been found that increased cognitive demand results in eye blink suppression Second, liars often attempt to control their behaviour in order to give a credible impression to the interviewer the higher the motivation to succeed in the lie the greater the likelihood that liars will attempt to control their behaviour. They called this the motivational impairment effect. |
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Describe limitations of the study (Mann Et Al.) |
Different interviewers were used for different participants Sometimes more than one interviewer was present The total number of people present varied depending on number of interviewers, presence of attorney, appropriate adult..etc. |
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What were the different tests that were made and what did the result show?(Mann Et Al.) |
t tests were used to test the average differences between the 2 coders did not differ none of these t tests were significant |
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Describe weaknesses (Mann Et Al.) |
16 participants is not a large sample. The study cannot be generalized, because of characteristics of liars to those in police custody. For example there is a chance that people who have been arrested are more likely to commit crimes, might experience less fear or guilt, might be more experienced liars, and might care less about consequences than non criminals who are in involved in high-stakes lies situations |
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Was there support for cognitive load? (Mann Et Al.) |
Two significant differences occurred: suspects blinked less and passed longer while lying. These findings give some support for cognitive load process in explaining deceptive behavior, as both fewer blinking and longer pauses are possible indicators of cognitive load. |
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Variables (DV and IV) (Mann Et Al.) |
Independent variable:Researchers did not manipulate an IV. It was a choice of a suspect whether to tell a lie or the truth, but the IV could be said to be a truth or a lie. Dependent variable:The dependent measure was the behaviour shown by the suspects on the videotape, which was observed and categorized. |
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Controls(Mann Et Al.) |
The researchers did not code the video clips because they may have been biased and ‘seen what they wanted to see’ The suspects’ truths and lies were confirmed by the police and because the suspects later confessed and admitted lies. The observers were not told what the study was about. They did not know whether a statement was true or false. They merely recorder the number of times each of the target behaviors occurred. |
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Method(Mann Et Al.) |
Natural experiment with naturalistic observation because the participants did not know their behaviour would be analysed for a psychological study |
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Describe the agreement of inter-rater reliability (Mann Et Al.) |
Inter-rater reliability between the two observers was excellent. Observations were analysed with pearson’s correlation test with correlation on a scale of 0 \9no agreement) to 1 (perfect agreement). Agreement was: Gaze aversion 0.86 Blinking 0.99 head movements 0.95 self manipulations 0.99 illustrators 0.99 hand/finger movements 0.99 speech disturbances 0.97 pauses 0.55 |
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Why is this study a quasi experiment?(Mann Et Al.) |
This study is described as a quasi experiment because the independent variable was not directly manipulated by the experimenter. |
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Outline the data collection process and explain why it was done that way(Mann Et Al.) |
Observers collected data by watching an hour-long video, consisting of clips of 16 suspects telling truths and lies. They were then asked to analyse the content by producing quantitative data, which was often numerical. That was done to simply detect trends and remove subjectivity or experimenter bias (seeing what they wanted to see) |
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Outline the data collected(Mann Et Al.) |
Quantitative data - an hour long videotape consisting of of clips of 16 suspects. The truths that were displayed were also comparable to the lies that the suspect made. The truth about their name was not comparable to a response to them committing murder for example. Total of 65 clips that varied in length. 27 truths and 38 lies. |
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Describe procedure |
Observers were instructed to code the one hour video footage, also called content analysis. They were not told the hypothesis or the nature of the clips, to enhance ignorance and deception. Once they coded the behaviors, they transformed into a manageable format so that the truths and the lies could easily be compared. The result was one truth-telling score and one lie telling score for each behavior of each participant. Then, two observers were asked to independently code the behavior. After all of this collection of data, a Pearson correlation statistical test was used between the two independent observers and the others, which showed a strong consistency between the two coders. This means that there was no significant difference between the two coders. |
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Results(Mann Et Al.) |
Behaviors recorded: Gaze AversionBlinkingPausesHead MovementsSpeech Disturbances (stuttering) -Behavioral results for the 6 categories were not significantly different -Noticeable differences were found between the hand and arm movements and pauses -The deceptive group paused longer and blinked less but there were many individual differences |
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Conclusions(Mann Et Al.) |
Note: Because they did not measure nor manipulate cognitive load and nervousness in this study, all conclusions are speculative. This gives some support for the cognitive load process in explaining deceptive behavior as both long pauses and fewer blinking suggest and indicate to cognitive load. However, because they did not manipulate or measure cognitive load and nervousness, all conclusions are speculative. |
