Elsevier

Psychoneuroendocrinology

Volume 84, October 2017, Pages 135-138
Psychoneuroendocrinology

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“Lie to me”—Oxytocin impairs lie detection between sexes

https://doi.org/10.1016/j.psyneuen.2017.07.001Get rights and content

Highlights

  • We examine how the hormone oxytocin affects lie detection.

  • It decreases the ability to correctly classify other-sex statements as truths/lies.

  • This effect may hint to its underlying mechanism as a catalyst for social adaption.

Abstract

The hormone oxytocin modulates various aspects of social behaviors and even seems to lead to a tendency for gullibility. The aim of the current study was to investigate the effect of oxytocin on lie detection. We hypothesized that people under oxytocin would be particularly susceptible to lies told by people of the opposite sex. After administration of oxytocin or a placebo, male and female participants were asked to judge the veracity of statements from same- vs. other-sex actors who either lied or told the truth. Results showed that oxytocin decreased the ability of both male and female participants to correctly classify other-sex statements as truths or lies compared to placebo. This effect was based on a lower ability to detect lies and not a stronger bias to regard truth statements as false. Revealing a new effect of oxytocin, the findings may support assumptions about the hormone working as a catalyst for social adaption.

Introduction

Lying is a fact of everyday life: Humans lie about their feelings, achievements, plans, reasons and facts in one out of three to five social interactions to protect or enhance themselves or others (DePaulo et al., 1996). Detecting lies, on the other hand, is a more difficult task: Humans are able to correctly identify messages as deceptive or truthful in only 54 of 100 cases (Bond and DePaulo, 2006). Thus, people‘s average ability to detect lies is barely above chance. However, people vary in their tendency to regard others as truthful (Bond and DePaulo, 2008). Particularly, people who are especially trusting in communications regard others as lying to a lesser extent (Levine and McCornack, 1991).

Oxytocin (OT) might influence this tendency. The nonapeptide modulates various aspects of social behaviors from increasing positive communication (Ditzen et al., 2009) to enhancing in-group cooperation and trust (De Dreu et al., 2010; but see Nave et al., 2015). A recent study indicates that OT even seems to have the power to make people more gullible. After male participants had watched video clips involving discussions between two TV show contestants, they predicted whether the contestants would cooperate or defect; the study revealed that people under OT had more difficulties predicting the contestants’ decisions than people under placebo (Israel et al., 2014). Although being an interesting example for OT’s effects on credulity, this study did not investigate lie detection but trustworthiness in risky social exchanges.

As underlying function, it has been argued that OT may promote social adaption by adjusting behaviors to fit social environments (Ma et al., 2016). Taking into account this social adaption framework, it seems plausible that people under OT are less able to detect lies. The most lies are told to benefit the liar making him or her appear kinder or smarter and protecting him or her from embarrassment or conflict (DePaulo et al., 1996). Giving deference to the ‘faces’ others are claiming, on the other hand, is important for everyday social life to proceed smoothly (Goffman, 1967, Goffman, 1971). Thus, being more generous with regard to lies more likely results in positive social relations. A lower ability to detect lies towards the opposite sex seems to be particularly “adaptive” with regard to an optimal adjustment to the social environment. Opposite-sex compared to same-sex relationships are characterized by higher uncertainty and ambiguity (e.g., Afifi, 1993), and individuals are most concerned with self-presentation when interacting with opposite-sex counterparts (Leary et al., 1994). Thus, to initiate and maintain social relations, trust is particularly important between males and females (Larzelere and Huston, 1980). OT, in turn, seems to be highly effective in this regard as research has shown that the hormone decreases the distance between members of the opposite sex (Preckel et al., 2014).

Therefore, we predicted OT to lower the ability to detect lies in females when facing men and in males when facing women. To test this prediction, male and female participants intranasally administered OT or a placebo and, analogue to previous research, judged the veracity of statements from male and female actors who lied or told the truth.

Section snippets

Participants and design

Seventy-nine participants (mean age = 22.96 years, SD = 5.33; 45 female, 34 male), were recruited around campus. Sample size determination was oriented towards past OT research (e.g., Radke and de Bruijn, 2015, Unkelbach et al., 2008; Nmean = 22 per condition), and data collection was stopped at the end of the academic term. Exclusion criteria were significant medical or psychiatric illness, medication, smoking more than five cigarettes per day, drug or alcohol abuse, allergies, hypersensitivity to

Results

For descriptive statistics, see Table 2.

Discussion

How successful are people under OT at detecting lies? If faced with the other sex, it does not bode well it seems. In our study, OT decreased the ability of male and female participants to correctly classify other-sex statements as truths or lies. This effect was based on a lower ability to detect lies (and not a stronger bias to regard truth statements as false). The participants’ affective state could not provide an explanation for our effects.

Although there seem to be small signs of

Contributors

All authors contributed to the study concept and the study design. Testing and data collection were performed by W. Erk and A. Reinelt. M. Pfundmair performed the data analysis and interpretation. M. Pfundmair drafted the manuscript, and W. Erk and A. Reinelt provided critical revisions. All authors approved the final version of the manuscript for submission.

Conflicts of interest

None.

Acknowledgment

The authors wish to thank Tabea Mehrbrodt for contributing to the study design and data collection.

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    This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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