Meta-Analysis on the Psychology of Lying

Synthesis of 565 studies reveals who lies most often

January 08, 2019

From cheating on tax returns to major corruption scandals—there is no denying that people often lie to their advantage. Numerous experimental studies have investigated individual and environmental factors that motivate people to lie. Researchers at the Max Planck Institute for Human Development and Technion—Israel Institute of Technology have conducted a comprehensive meta-analysis synthesizing the results of 565 studies on dishonesty. Their findings show that dishonesty is associated with age and gender. The study has been published in Psychological Bulletin.

The fundamental conflict underlying every lie is a choice: Either you tell the truth and risk missing out on something or you lie in a bid to better your position. Why people lie depends on individual and environmental factors. To examine these factors empirically, many published studies have simulated this fundamental conflict in simple experiments such as the coin-flip task. Here, participants toss a coin out of view of the experimenter. They then report the outcome to the experimenter—for example, by computer. If they toss a head, they win a small amount of money; if they toss a tail, they get nothing. When this experiment is repeated again and again with large numbers of participants, the ratio of heads to tails should be fifty-fifty. But almost all studies find that participants report more heads than tails. In other words, at least some participants lie in order to “earn” more money.

Over the last decade, researchers have conducted numerous studies using this or a similar set-up to investigate the various factors that lead to dishonesty. Do nuns lie more often than prison inmates? Are people more likely to lie online or over the phone? Are they more dishonest when more money is at stake? In their meta-analysis, researchers at the Max Planck Institute for Human Development and Technion – Israel Institute of Technology analyzed data from 565 studies and a total of 44,050 participants. “Although a wealth of studies have investigated who lies, when they lie, and why, the findings are mixed and sometimes contradictory. By using this large set of data from all the studies, we can now draw clearer conclusions on some of the factors involved,” says Philipp Gerlach, adjunct researcher at the Max Planck Institute for Human Development and lead author of the study.

Overall, 42% of all men and 38% of all women in the experiments lied. The meta-analysis thus confirmed that men lie more than women—although the difference was not pronounced. In addition, younger people lied more than older people. The probability of lying decreased by 0.28 percentage points with each year of life, from about 47% for a 20-year-old to just 35% for a 60-year-old. Other factors often suggested to play a role did not prove to be associated with dishonesty. For example, there was no indication that business students lie particularly frequently.

The meta-analysis drew on published and unpublished studies from the fields of psychology and economics that have used a small but diverse set of experimental setups to investigate the prevalence of dishonesty. Some, such as the coin-flip task, involve a random outcome. Others test participants’ abilities, such as whether they manage to solve a math puzzle. The researchers found that these structural differences in the experimental set-up influenced participants’ behavior, leading to differences in findings on the prevalence of dishonesty. “If you want to gauge the likelihood of people behaving dishonestly, you need to take into account the experimental situations and temptations they face. Our findings suggest that dishonesty is not simply an individual characteristic, but that it interacts systematically with the environmental conditions,” says Ralph Hertwig, Director of the Center for Adaptive Rationality at the Max Planck Institute for Human Development.

Original Publication
Gerlach, P., Teodorescu, K., & Hertwig, R. (2019). The truth about lies: A meta-analysis on dishonest behavior. Psychological Bulletin, 145(1), 1–44. doi:10.1037/bul0000174

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