Does Once a Cheater Mean Always a Cheater?
A new study explored how likely it is that someone who cheats once cheats again.
Posted May 31, 2025 | Reviewed by Gary Drevitch
Is someone who cheats on their partner also more likely to cheat in an exam or in a poker game to win more money? And are they more likely to also evade taxes? The question of whether someone who shows unethical behaviour like cheating in a game does so “just once” because the situation gives them the opportunity, or whether the tendency to cheat is a consistent part of the person’s personality has not been answered clearly in psychological research.
A new study on the consistency of cheating over time
A new study entitled “Cheat, cheat, repeat: On the consistency of dishonest behavior in structurally comparable situations" and just published in the scientific Journal of personality and social psychology , focused on the research question to what extend cheating is something that some people do again and again over time ( Thielmann and co-workers, 2025 ). The research team, led by Isabel Thielmann from the Max Planck Institute for the Study of Crime , Security and Law in Freiburg, Germany, analysed data from a large group of volunteers that was collected at several different time points.
At the first time point, more than 2900 volunteers filled out questionnaires about their personality and the dark factor of personality—an integrative measurement of various “dark” personality traits such as narcissism , psychopathy , amorality, egoism, greed, Machiavellianism , sadism, and spitefulness. These questionnaires also included questions on honesty and dishonesty.
At the second time point, the same 2900 volunteers participated in the so-called "mind game," a behavioural measure of dishonesty. In this experiment they had to write down a number between 1 and 8 on a piece of paper. Next, they were shown a random number between 1 and 8 on a screen. They then had to respond “Yes” or “No” to the question whether the number they had written on the paper matched the number on the screen. If they indicated “Yes”, they received 2 euros; if they indicated "No", they received no money. The volunteers were informed that the scientists could not check whether the response was truthful, or not. Thus, in principle, a volunteer could always say “Yes” to get the maximum amount of money.
At the third time point, dishonesty was measured again using another task, the so-called coin-toss task. About 1,900 of the volunteers who participated in the first two measurements also participated in this one. The volunteers were asked to choose a side of a coin (heads or tails) and then throw a coin exactly three times. They then had to report “Yes” or “No” on whether they hit the chosen side of the coin on all three trials. Comparable to the first task, a “Yes” answer resulted in a payment of 2 Euros and a “No” answer resulted in no monetary reward.
About 3 years later, the last measurement of the experiment took place. About 800 of the original volunteers also participated in this last part of the experiment. At this time point, volunteers had to complete a lottery task. Each volunteer was shown a randomly chosen month of the year and had to indicate whether it matched their mother's birth month. Saying “Yes” earned the volunteers 5 euros, while saying "No" resulted in no money at all. Again, volunteers were told that the scientists had no way of checking whether they told the truth or not.
The scientists took the probability of winning (1-in-8 in the mind game and coin-toss game, and 1-in-12 in the lottery task) and compared it to the “Yes” answers of the volunteers to determine the percentage of dishonest participants who lied to win more money. In general, it was rather unlikely that someone would win in any of the 3 tasks. In all three tasks, the percentage of “Yes” answers where higher than would be expected if everybody answered truthfully:
Thus, volunteers were dishonest a lot, especially in the lottery game. The scientists then used complex statistical modelling to determine how likely it was that someone cheated in several different games. They found strong, statistically significant associations: If someone cheated in the first game to gain more money, they were also highly likely to cheat in the second and third games. For example, if someone was dishonest in the mind game, the probability of also being dishonest in the coin toss game was 43.8%. In contrast, if someone was honest in the mind game, the probability of them being dishonest in the coin toss game was only 6.3%. Remarkably, the consistency in cheating was also given for the third task, which took place almost 3 years later than the others. Interestingly, the dark factor of personality showed a significant link to being consistently dishonest in several tasks: The higher the dark factor was, the more likely a volunteer was to lie on more than one task.
Takeaway: Someone who cheats once is very likely to cheat again
Taken together, the results of the study were crystal clear: Dishonest behaviour was highly consistent across tasks and time. Someone who cheated once in these tasks to gain more money was highly likely to do it again. This suggests that dishonesty is not something that “just happens" once but a consistent personality trait. Thus, someone who cheats once is highly unlikely to change their personality: They will do it again and again.
Facebook image: polkadot_photo/Shutterstock
Thielmann, I., Hilbig, B. E., Schild, C., & Heck, D. W. (2025). Cheat, cheat, repeat: On the consistency of dishonest behavior in structurally comparable situations. Journal of personality and social psychology , 128 (5), 1209–1225. https://doi.org/10.1037/pspp0000540
Share this post Facebook Bluesky Linkedin Email
There was a problem adding your email address. Please try again.
By submitting your information you agree to the Psychology Today Terms & Conditions and Privacy Policy
Sebastian Ocklenburg, Ph.D., is a professor for research methods in psychology at the Department of Psychology at MSH Medical School in Hamburg, Germany. His research focuses on left-handedness and brain asymmetries.
Get the help you need from a therapist near you–a FREE service from Psychology Today.
This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.