When people first started lying, the amygdala showed more activity. But the more the participant lied, the less active the amygdala got. And the magnitude of self-serving lies grew with repetition. "This experimental result is consistent with anecdotal observations of small digressions gradually snowballing into larger ones," the authors write.

A study of what goes on in the brain when someone tells a lie could offer a biological explanation for why untruths often "snowball over time." When people tell small fibs, their brain becomes desensitized to the emotional twinge that dishonesty usually causes. Lying becomes easier and telling ever-bigger self-serving whoppers becomes more likely, they found.

In an experiment we carried out with colleagues Stephanie Lazzaro and Dan Ariely – published in Nature Neuroscience – we gave 80 people the opportunity to lie again and again on a financial task in order to gain money at another person’s expense. We found that people started with small lies, but slowly, over the course of the experiment, lied more and more. This escalation of dishonesty was observed only when participants lied for their own benefit, not when they did so solely for the benefit of others. Examining people’s brain activity while they were being dishonest in our task revealed another reason – a biological process called emotional adaption… the brain’s emotion network responds less and less with each additional lie. The greater the drop in the brain’s sensitivity to dishonesty, the more people lied the next time they got a chance. In other words, people adapted to their own dishonesty and less was holding them back from telling bigger lies.

The research is the first of its kind in providing empirical evidence that our brains adapt to escalating lies over time. When a person lied for the first time, it heavily activated the brain region known as the amygdala. The amygdala's response declined, however, with each subsequent lie. Scientists were especially surprised to find that larger decreases in amygdala activity could accurately predict that someone would tell bigger lies in the future.

Across six experiments we provide evidence that repeated transgressions can lead to a transition to continuous dishonesty. Participants engaged in tasks where they could tell self-serving lies of varying magnitudes over multiple rounds. The results show that initially small dishonest acts can, under certain conditions, generalize into broader, more frequent ethical transgressions, consistent with the notion of a behavioral slippery slope in dishonesty.

The researchers then used brain scans to show that our mind's emotional hot spot — the amygdala — becomes desensitized or used to the growing dishonesty. Telling little fibs leads down a slippery slope to bigger lies — and our brains adapt to escalating dishonesty, which makes deceit easier, a new study shows.

Here, we provide empirical evidence for a gradual escalation of self-serving dishonesty and reveal a neural mechanism supporting it. Our behavioral findings reveal that self-serving dishonesty escalates over the course of the block. The findings uncover a biological mechanism that supports a “slippery slope”: what begins as small acts of dishonesty can escalate into larger instances. The amygdala’s response to self-serving (but not self-harming) lying declined with every lie while the magnitude of the lies escalated. Critically, the extent of reduced amygdala sensitivity to dishonesty on a present decision relative to the previous one predicts the magnitude of escalation of self-serving dishonesty on the next decision.

Telling small lies desensitises our brains to the associated negative emotions and may encourage us to tell bigger lies in future, reveals new UCL research funded by Wellcome and the Center for Advanced Hindsight. The research, published in Nature Neuroscience, provides the first empirical evidence that self-serving lies gradually escalate and reveals how this happens in our brains. They found that the amygdala, a part of the brain associated with emotion, was most active when people first lied for personal gain. The amygdala's response to lying declined with every lie while the magnitude of the lies escalated. Crucially, the researchers found that larger drops in amygdala activity predicted bigger lies in future.

Telling small lies desensitizes our brains to the associated negative emotions and may encourage us to tell bigger lies in future, reveals new UCL research funded by Wellcome and the Center for Advanced Hindsight. The research, published in Nature Neuroscience, provides the first empirical evidence that self-serving lies gradually escalate and reveals how this happens in our brains. They found that the amygdala, a part of the brain associated with emotion, was most active when people first lied for personal gain. The amygdala's response to lying declined with every lie while the magnitude of the lies escalated. Crucially, the researchers found that larger drops in amygdala activity predicted bigger lies in future. "When we lie for personal gain, our amygdala produces a negative feeling that limits the extent to which we are prepared to lie," explains senior author Dr Tali Sharot. "However, this response fades as we continue to lie, and the more it falls the bigger our lies become. This may lead to a 'slippery slope' where small acts of dishonesty escalate into more significant lies."

The moral slippery slope effect refers to the phenomenon where, within groups or organizations, the incidence of individual unethical behaviors increases over time as people repeatedly face similar ethical decisions. For example, Welsh et al. (2015) conducted a three-round matrix-solving task with increasing monetary rewards across rounds. They found that the lying rate gradually rose across rounds, thereby confirming the effect’s existence. Garrett et al. (2016) also reported that participants told significantly more lies as rounds increased. Over the long term, the incidence of unethical behavior serves as a key indicator of the moral slippery slope effect (Effron et al. 2015; Garrett et al. 2016; Anderson et al. 2024).

The study empirically demonstrates the slippery-slope effect, where small ethical transgressions lead to larger violations over time. Drawing on social-cognitive theory, we show how the mechanism of moral disengagement can reduce ethicality over a series of gradually increasing indiscretions. We find support for the developed model across 4 multiround studies, in which participants’ unethical behavior increased across rounds when initially minor transgressions were allowed and then progressively escalated. Inducing a prevention focus moderates this mediated relationship by reducing one’s propensity to slide down the slippery slope.

The findings suggest that the brain becomes desensitized over time to the negative emotional effects of lying. As lying progressed, the response in participants' amygdalas decreased — and the bigger the decrease, the bigger their next lie would be.

The slippery slope refers to behavior in which individuals’ participation in small unethical infractions leads them to engage in more egregious behaviors over time. In an effort to comprehend the factors that foster unethical behavior in the corporate landscape, significant emphasis has been placed on the 'slippery slope' in decision-making. This concept describes a scenario in which individuals’ involvement in minor unethical infractions leads to progressively more serious misconduct over time. Anecdotal evidence, along with empirical research in psychology, supports the notion that minor ethical violations can pave the way for more significant unethical actions.

Small, self-serving lies may desensitize our brains to the uneasiness usually caused by such falsehoods, thus encouraging us to tell bigger lies in the future, according to a British study published Monday in the journal Nature Neuroscience. Specifically, the study found that dishonesty gradually increases with repetition and that this escalation is associated with a progressive decline of activity in the amygdala, an area of the brain associated with emotion, including shame and guilt. These brain scans revealed a sudden jump in activity in the amygdala when the participants lied for their own benefit for the first time. With each subsequent lie, however, the activity in the amygdala declined. Furthermore, the larger the drop in amygdala activity, the bigger the subsequent lie. “It is likely the brain’s blunted response to repeated acts of dishonesty reflects a reduced emotional response to these acts,” said Neil Garrett, a co-author of the study.

Dishonesty is a slippery slope: If you behave dishonestly once, you may become more likely to do so again in the future, a new study from England shows. The reason may be that the brain grow less sensitive to self-serving dishonest behavior over time, the researchers said. People's dishonesty escalated over the course of these trials, found the study, published online today (Oct. 24) in the journal Nature Neuroscience. The results showed that the amygdala, a part of the brain connected to emotions, showed a marked reduction in activity in response to self-serving dishonesty over the course of the trials. In fact, researchers found that the amount of the reduction in the amygdala's activity for each trial could predict the amount that the participant's dishonesty would increase in the next trial: The bigger the fall in amygdala activity during one trial, the bigger the lie would be the next time. "It is likely [that] the brain's blunted response to repeated acts of dishonesty reflects a reduced emotional response to these acts," Garrett said.

Scientists have observed changes in the human brain as study participants tell lies—specifically, as white lies became outright deception, the amygdalas of the fibbing volunteers became less active. The researchers’ findings, published in Nature Neuroscience yesterday (October 24), offer a possible neural mechanism for a common human failing, that lying can lead to more extensive dishonesty. “The reduction in activity in the amygdala can predict how much people increase dishonesty subsequently,” study coauthor Neil Garrett, a psychologist at University College London, told The Verge. The volunteers were given incentives to lie, and after they had fibbed previously, fMRI data showed reduced activity in the amygdala when people were dishonest again.

Referred to as the “slippery slope,” incrementalism describes how we unconsciously lower our ethical standards over time through small changes in behavior. This is the slippery slope at work. And if we are not careful we can easily go from minor transgressions in our workplace, such as taking a few office supplies home for personal use or lightly padding our expense account, to more serious transgressions. Francesca Gino and Max Bazerman… observed humans, and found that we unconsciously lower the bar over time through small changes in ethicality. Most multi-million dollar securities frauds start with executives fudging fairly small numbers but over time those numbers grow through incrementalism.

This study suggests that the negative feelings we have about telling lies provide important information and can help us avoid getting caught in a cycle of dishonesty. Over time, as participants lied again and again, these areas of the brain showed less and less activity. When lying no longer stirs up negative feelings, we are able to increase the magnitude of our lies.

A study led by University College London researchers Neil Garrett and Tali Sharot provides the first empirical evidence that self-serving lies gradually escalate and reveals how this happens in our brains. “We provide empirical evidence that dishonesty gradually increases with repetition when all else is held constant.” They found that the amygdala, a brain area intricately involved in emotional responses, was most active when people first lied for personal gain. The amygdala’s response to lying declined with every lie while the magnitude of the lies escalated. The team also found that larger drops in amygdala activity predicted bigger lies in future. “Critically, the extent of reduced amygdala sensitivity to dishonesty on a present decision relative to the previous one predicts the magnitude of escalation of self-serving dishonesty on the next decision.” “This may lead to a ‘slippery slope’ where small acts of dishonesty escalate into more significant lies,” Dr. Sharot added.

Results showed that lying decreased people's self-esteem and increased negative affect, regardless of the type of lie (self-centred vs. other-oriented). In the present study, we examined the consequences of lying for the liar, focusing on two aspects of subjective well-being: self-esteem and affect. Participants in the lying condition reported lower levels of self-esteem than did those in the honesty condition. Participants in the lying condition also reported higher levels of negative affect than did those in the honesty condition. These findings suggest that lying, even when it is self-centred or other-oriented, can have costs for the liar, which may influence future behaviour.

The brain is a malleable machine—even when it comes to lying. A team of scientists has concluded that your brain adapts itself to dishonesty. Specifically, the act of telling a self-serving lie (no matter how small) paves the way for bigger falsehoods. “Behaviorally, we show that the extent to which participants engage in self-serving dishonesty increases with repetition,” the scientists wrote in the study’s abstract. They noted that activity in the amygdala, a part of the brain that deals with emotion, decreases with each subsequent lie. In addition, the extent of that decrease predicted the enormity of the next lie. As lying increased, the response in the amygdala decreased. And the size of the decline from one trial to another predicted how much bigger a subject’s next lie would be. These findings suggested that the negative emotional signals initially associated with lying decrease as the brain becomes desensitized.

This study set out to investigate the type of media individuals are more likely to tell self-serving and other-oriented lies, and whether this varied according to personality variables. Self-serving lies were defined as lies that benefit the liar, whereas other-oriented lies benefit another person. Participants reported telling a greater proportion of self-serving lies than other-oriented lies in face-to-face communication. The study provides evidence that self-serving lies are common in everyday life, though it does not directly examine whether small lies escalate into larger ones over time.

A new study finds evidence of "a gradual escalation of self-serving dishonesty," in which small lies pave the way for larger deceptions. In the experiment, participants initially lied only a little for their own benefit, but over time their dishonesty escalated. The researchers used brain imaging to track activity in the amygdala, a region linked to emotion, and found that its response to self-serving dishonesty diminished with repetition. This pattern suggested that as people repeatedly told small fibs, their emotional response to lying weakened, making it easier to tell bigger lies.

We now have experimental evidence that we have a natural propensity to be dishonest, and that this dishonesty can escalate over time. In a recent study, participants repeatedly had the opportunity to lie for financial gain at another person’s expense. Initially, they told small lies, but as the experiment progressed, they began to tell larger lies. Brain imaging showed reduced activity in the amygdala, a region involved in emotional responses, as people continued to lie, suggesting that they became desensitized to their own dishonesty.

We observe frequent but not omnipresent over-reports for oneself (self-serving lying). Lying propensities in our experiment are similar at all ages; only middle schoolers engage in slightly more self-serving lying than the other age groups. Surprisingly, reports for themselves are uncorrelated across rounds, which is at odds with standard theories of constrained optimal choice given a fixed (direct or indirect) cost of lying. Our data do not show a simple escalation of self-serving lying over repeated rounds, suggesting that in this schoolyard context, lying behaviour may not follow a straightforward slippery-slope pattern.

We lie to ourselves to protect our self-images, which allows us to act immorally while maintaining a clear conscience. In all these ways, our brains can fool us into believing things that are not true. Self-deception allows us to inflate our opinion of our own abilities, so that we believe we are smarter than everyone around us. It means that we overlook the repercussions of our actions for other people, so that we believe that we are generally acting in a moral way. It may be that the bigger the stakes, the greater the lies we are able to tell ourselves. Although this article focuses on self-deception rather than interpersonal lying, it describes psychological processes by which repeated self-serving distortions can make larger moral violations more acceptable.

Dishonesty is a slippery slope: If you behave dishonestly once, you may become more likely to do so again in the future, a new study from England shows. People's dishonesty escalated over the course of these trials, found the study, published online today in the journal Nature Neuroscience. The results showed that the amygdala, a part of the brain connected to emotions, showed a marked reduction in activity in response to self-serving dishonesty over the course of the trials. In fact, researchers found that the amount of the reduction in the amygdala's activity for each trial could predict the amount that the participant's dishonesty would increase in the next trial: The bigger the fall in amygdala activity during one trial, the bigger the lie would be the next time. In other words, whenever a person lies for personal gain, the amygdala produces a negative feeling that helps curb that act — but the more often a person lies, the more the response fades, leading to a slippery slope that may encourage an escalation of dishonest behavior.

The self-serving lie is all too common, even with basically good people who just happen to think a little more highly of themselves than they deserve. The self-serving lie is all too common, and people who tell lies in this way often believe them. The author, a psychotherapist, argues from clinical experience that habitual self-serving distortion of reality can reduce guilt and make continued dishonesty more likely, though this is not presented as controlled experimental data.

The paper addresses so-called slippery slope arguments, which are usually used as warnings against accepting a certain view or undertaking a certain action because it will lead, through a series of small steps, to a highly undesirable outcome. It distinguishes between logical slippery slopes, where accepting one claim commits one to accepting another, and empirical slippery slopes, where undertaking a small initial action is claimed to causally increase the likelihood of later, more extreme actions. Empirical slippery slopes in ethics often involve claims that minor transgressions can desensitize agents and make more serious transgressions more probable.

Together, the results indicate that youth exposed to moderate levels of violence experience more internalizing distress than those exposed to little or no violence, and in turn engage in less violent behavior several years later. These longitudinal results provide stronger support for the hypothesis that exposure to high levels of violence and violence experienced in multiple contexts lead to emotional desensitization.

Experimental psychology and neuroscience research have demonstrated that repeated self-serving lies can lead to reduced emotional responses in brain regions such as the amygdala, and that this desensitization is associated with larger subsequent lies. The concept of a "slippery slope" in moral behaviour is widely discussed in moral psychology, where initial small transgressions can change self-standards and make greater violations more likely. This background knowledge summarizes the broader scientific context around the specific Nature Neuroscience study on dishonesty escalation.

The slippery slope argument is a figure of reasoning by which an action that seems morally acceptable is conclusively shown to be morally impermissible in reaction to its morally unacceptable consequences. In ethical debates, such as those surrounding active euthanasia, slippery slope arguments often claim that permitting a small change (or minor transgression) will lead, step by step, to more radical and morally problematic changes. While this page focuses on euthanasia, it illustrates the general structure of claims that incremental actions can increase the likelihood of more extreme outcomes later.