Mann -- Lying

Question 1

Define deceptive behavior.

Answer 1

Behavior that indicates lying

Question 2

What is the Old theory of Non-functional movement in liars?

Answer 2

People who are lying avoid eye contact, fidget or act nervous, touch their face, or put hands over eyes or mouth.

Question 3

What does the previous research say?

Answer 3

There is no relationship between eye contact and deception and they usually become unnaturally still

Question 4

What was the previous method to observe lying behavior? What was the issue?

Answer 4

Experimental lab.

Lying wasn’t natural.

Question 5

Define cognitive load.

Answer 5

The total amount of mental effort being used in the working memory

Question 6

AIMS/Hypothesis?

Answer 6

AIM 1: to investigate whether there are systematic differences in behavior between lying and truth telling

AIM 1: to investigate individual differences in behavior during lying and truth telling

AIM 3: to investigate real-life lying

AIM 4: to investigate high stakes lying

AIM 5: to extend the work of Vrij and Mann

Hypothesis: liars will not display nervous behavior because…

1. Cognitive load and behavioral control
2. Previous research supports that liars become unnaturally still, do not decrease eye contact, and that there is no relationship between eye contact and deception

Question 7

Participants/sampling?

Answer 7

16 police suspects (9 theft, 2 arson, 1 attempted rape, 4 murder)

13 males, 3 females

4 juveniles (13-15) and 12 adults (below 65)

15 Caucasian, one Asian

10/16 already known to police/had been previously interviewed

Got interviews from U.K. police department (self-selecting)

VERY HIGH ECOLOGICAL VALIDITY!!

Question 8

Sampling for truths/lies?

Answer 8

Files were scoured looking for forensic evidence or substantial reliable independent witness statements to corroborate instances of truth or lie as implicated by the investigating officer

O R

In some cases the suspect initially denies any involvement in the crime, and then confesses after being presented with substantial forensic/witness evidence

Question 9

Method?

Answer 9

Natural experiment with observation

Question 10

Design?

Answer 10

Repeated measures (participants are told both truths and lies)

Question 11

Experimenters?

Answer 11

Mann et. al set up the study and then analyzed the results but didn’t code the video clips

Coding was done by two naïve observers

Question 12

Observation coding?

Answer 12

2 observers watched the clips, not knowing the study, and would code if the behavior happened

At the end of the tape it would be determined which behaviors happened the most and whether these were during the lie or the truth

Question 13

Behaviors coded?

Answer 13

Gaze aversion, blinking, head movements, self-manipulations, illustrators, hand/finger movements, speech disturbance, pauses. KNOW WHAT IS MEANT BY EACH OF THESE

Question 14

Controls?

Answer 14

Double blind design (participants and observers did not know the AIM, researchers didn’t do coding)

Suspects’ ‘truths’ and ‘lies’ were confirmed

Info such as name and address were not included in the clips due to the ease of answering these questions

Question 15

Apparatus?

Answer 15

A 1 hour videotape with 65 clips of the 16 suspects

27/65 clips were truths and 38 were lies

Each suspect had between 2 and 8 clips

Each clip lasted 41 seconds-6 mins

Coding scheme/response categories on which the observers could record their observations

Question 16

Independent variables?

Answer 16

Truth or lie

Question 17

Procedure for the observation of video?

Answer 17

1. Video tapes of authentic liars from police records were obtained. Clips were broken down so there was at least one truth and one lie per participant. A final tape was created, lasting one hour.
2. Observer 1 watched all clips and coded behaviors
3. Observer 2 watched 36 clips, at least one of each participant, and coded behavior
4. Checks were done to see it there was strong agreement (inter-rater reliability)

Question 18

Wha is inter-rater reliability and how does it apply to this study?

Answer 18

Mann et al. ran a Pearson’s r to determine if the two observers had a strong correlation in coding the behaviors. Here’s what they found: (0 no agreement, 1 perfect agreement)

Blinking, self-manipulations, illustrators, hand/finger movement: .99

Speech disturbances: .97

Gaze aversion: .86

Pauses: .55

Question 19

Data?

Answer 19

Quantitative data was gathered: each time a behavior was observed, it was recorded

Coding was then converted to truth-telling score and lie-telling score

Means and standard deviations were calculated and the results were analyzed for meaning

Question 20

Findings?

Answer 20

No difference:
Head movement and speech disturbance
–50% increased, 50% decreased when lying

Gaze aversion
–56% showed more, 44% showed less

More participants:
Hand and arm movement
–69% showed a decrease

Most reliable indicators:
Blinking and pauses
–81% blinked less when lying
–81% paused longer when lying

Question 21

Explain their findings?

Answer 21

There are NO behaviors that all liars exhibit!! Each person exhibits individual differences or deceptive behavior.

Comparison between high-stakes liars and high-stakes truth tellers was omitted because the behaviors might be too similar.

Question 22

Conclusions?

Answer 22

Challenges simplistic view that a typical deceptive behavior exists.

Demonstrated large individual differences.

Cognitive load processes occur during lying.

CONTRADICT the belief that liars behave nervously.

Hypotheses are confirmed.

Question 23

Validity?

Answer 23

The videotape consists of genuine police interviews…is it studying what it claims to be?

Is there even such a thing as authentic high-stakes liars?

Question 24

Generalizations? (Is it ecologically valid?)

Answer 24

Can the results be generalized?

Yes, confirmed by previous research.

Does the ecological validity strengthen the ability to generalize?

Question 25

Reliability?

Answer 25

Yes!

• HIGH Inter-rater reliability
• Objective measures such as blinking

No!

• Some measures like pauses were subjective
• Some behaviors had huge individual differences (KNOW WHICH ONES!!)

Question 26

Ethnocentric bias?

Answer 26

How is ethnocentric bias present in this study?

WE DON’T KNOW WHAT BEHAVIORS OTHER CULTURES EXHIBIT WHEN LYING!