Here, we provide empirical evidence for a gradual escalation of self-serving dishonesty and reveal a neural mechanism supporting it. Behaviorally, we show that the extent to which participants engage in self-serving dishonesty increases with repetition. Critically, the extent of amygdala BOLD reduction to dishonesty on a present decision relative to the last predicts the magnitude of the next self-serving lie.

A study published in Nature Neuroscience found that when people told self-serving lies, their brains became less responsive over time. The researchers said the reduction in amygdala activity was linked to larger lies in later rounds, consistent with a ‘slippery slope’ effect.

Researchers reported that telling a small self-serving lie can make it easier to tell larger lies later. In the experiment, dishonesty increased with repetition, and brain scans showed reduced amygdala response as lying continued.

Reuters reported on the UCL-led study as finding that small lies can make people more comfortable with dishonesty and can escalate into bigger lies. The report says researchers observed that the brain’s response to lying diminished over time while the size of lies increased. It also notes that greater reductions in amygdala activity were associated with larger lies later.

The authors write that in social-cognitive theory, "with repeated use of moral disengagement mechanisms and commission of immoral acts, [individuals] stop experiencing self-censure and can commit increasingly immoral acts." They specifically examine lie‑telling, noting that moral disengagement processes help children justify lying and that higher moral disengagement is associated with greater frequency of lies and more antisocial lying behavior.

In this experimental study, the authors report that "the neural response to dishonesty decreased with repetition" and that "the reduced sensitivity was associated with a progressive increase in self‑serving dishonesty." They conclude that "small acts of dishonesty can lead to larger acts of dishonesty" because repeated self‑serving lies attenuate amygdala responses, reflecting reduced emotional aversion, which in turn facilitates escalation of dishonesty over time.

Across multiple experiments, the authors found that "committing a small ethical transgression increased the likelihood of committing a larger ethical transgression in the future" when individuals were able to morally justify the initial act. They argue that moral disengagement and rationalization processes render minor wrongdoing acceptable, thereby "desensitizing" individuals and making it easier to engage in more severe dishonesty subsequently.

The study found that when people first started lying, the amygdala responded strongly, but as they continued, the response went down. The sharper the decrease, the greater a volunteer’s lie in the next round, supporting the idea that small self-serving lies can pave the way for bigger ones.

UCL reports that telling small lies desensitises the brain to the associated negative emotions and may encourage people to tell bigger lies in future. The article says the amygdala was most active when people first lied for personal gain, then its response declined as the lies escalated. It adds that larger drops in amygdala activity predicted bigger lies later.

New research found that little self-serving lies can make people comfortable with larger deceptions. The researchers observed that the more participants lied for personal gain, the less active the amygdala became, and the magnitude of self-serving lies grew with repetition.

Bandura describes a set of cognitive mechanisms that allow individuals to "disengage self‑sanctions from harmful conduct" without changing moral standards. He notes that repeated use of these mechanisms can "gradually strip away moral self‑sanctions" so that people can perpetrate increasingly harmful or unethical acts. The paper emphasizes that moral justification, euphemistic labeling, and minimizing consequences can normalize initially small transgressions and pave the way for more serious ones.

The researchers concluded that the act of telling a self-serving lie, no matter how small, paves the way for bigger falsehoods. They reported that self-serving dishonesty increased with repetition and that amygdala activity declined as lying escalated.

The entry explains that moral disengagement is "the process of convincing the self that ethical standards do not apply to oneself in a particular context." It states that "higher levels of moral disengagement lead to increased likelihood of unethical decision making" and describes how moral justification and displacement of responsibility facilitate behaviors such as "outright lying" and attempts to obscure the truth by reducing self‑condemnation over time.

This theoretical paper argues that "frequent, antisocial lies as a maladaptive problem‑solving mechanism" are linked to moral disengagement. It suggests that viewing children's justifications for lying through the lens of moral disengagement can help explain "how chronic lying develops," implying that repeated self‑serving lies, supported by disengagement mechanisms, can desensitize children to the moral implications of dishonesty and increase their tendency to lie more.

One self-serving lie leads to another, and the lies get bigger and bigger. The article describes the study as evidence that repeated dishonesty reduces guilt or another emotional response, making further lying more likely.

ScienceDaily says telling small lies desensitizes the brain to the negative emotions associated with lying and may encourage bigger lies in the future. It summarizes the Nature Neuroscience paper as finding that the amygdala response declined with each lie while the magnitude of the lies escalated. The piece also states that larger drops in amygdala activity predicted bigger lies later.

The authors describe emotional desensitization as "a numbing or blunting of emotional reactions" and state that it may "increase [youths'] propensity for perpetrating violence." They explain that, in the pathologic adaptation model, cognitions that normalize violence such as moral disengagement "are seen as precipitants of aggressive behaviors" and that moral disengagement can act as a coping mechanism that decreases distress while facilitating subsequent harmful conduct.

This later article argues that dishonesty can involve transient affective processes and that emotional habituation may weaken the negative feelings associated with lying over time. It states that if the affective component of lying is weakened or removed, that may lead to more lies and a slippery slope in which digressions start small and escalate. The paper positions repeated lying as a process that can change future dishonest behavior.

This news piece on the Nature Neuroscience research states: "Deceit is a practiced trait, according to a study released Monday that said small lies desensitizes the brain to negative emotions, possibly leading to bigger lies in the future." It explains that when a person lied for the first time, "it heavily activated the brain region known as the amygdala" but "the amygdala’s response declined, however, with each subsequent lie, even if the lie’s magnitude significantly increased." The article notes that "larger decreases in amygdala activity could accurately predict that someone would tell bigger lies in the future" and quotes senior author Tali Sharot: "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."

Summarizing Bandura’s work, the article defines moral disengagement as the process by which a person convinces themselves that ethical standards do not apply in a particular situation. It notes that through mechanisms such as moral justification, individuals can rationalize acts like "lying under oath" and feel less guilt, and it emphasizes that understanding and overcoming these mechanisms is important because they allow people to rationalize increasingly serious wrongdoing over time.

In this dissertation, the author reports that "using various ways of measuring pathological lying, pathological lying was consistently associated with moral disengagement, criminality, and dark traits." The findings suggest that individuals who engage in extensive lying show higher levels of moral disengagement, supporting the idea that repeated dishonesty is linked to cognitive processes that reduce moral concern and facilitate more serious unethical behavior.

The video explains that moral disengagement "describes the mental processes we use to convince ourselves that our actions are acceptable even when they violate our moral standards" and notes that "often we use moral disengagement to rationalize little lies or small moral missteps." It suggests that these rationalizations can erode moral awareness, making it easier to continue and potentially escalate unethical behavior.

Florida Tech News summarizes the study as showing clear evidence of escalation in self-serving dishonesty. It says the magnitude of dishonesty got larger and larger as the trials progressed, and that the brain’s responsiveness reduced or accommodated to the dishonesty over time. The article frames this as people adapting to being dishonest.

Discussing the Sharot et al. work, the TED Blog describes "the cascading effect of small lies" and notes that the paper "sheds light on the possible slippery-slope effect of telling small, self-serving lies." Using fMRI, "the researchers found that when participants believed lying was to their benefit, 'they were more inclined to dishonesty and their lies escalated over time.'" Additionally, "as their lying progressed, the response in their amygdalas decreased — and the bigger the decrease, the bigger their next lie would be. The findings suggest that the brain becomes desensitized over time to the negative emotional effects of lying." The post also reports that Sharot cautions that while decreased activity is clearly related to lying, whether it is specifically a negative emotional reaction remains "speculation."

This commentary on the Nature Neuroscience study explains that in the experiment, "dishonesty snowballed—lies started small but increased steadily in magnitude over time." Early trials showed "a great deal of activity in regions of the brain associated with emotions—the amygdala in particular," suggesting participants initially felt bad about lying. "But over time, as participants lied again and again, these areas of the brain showed less and less activity." The piece concludes: "When lying no longer stirs up negative feelings, we are able to increase the magnitude of our lies. Then the additional, larger lies further deaden our sensitivity to the act of lying, and the slippery slope continues." It explicitly interprets the findings as empirical support for the idea that "small lies tend to lead inexorably to larger lies."

The Society for Personality and Social Psychology summarises a study on dishonesty: "Telling small lies desensitizes our brains to the associated negative emotions and may encourage us to tell bigger lies in future." The post describes evidence that repetition of self-serving dishonesty reduces emotional responses, which in turn is linked with escalation of lie magnitude, framing this as scientific support for the notion that minor self-serving lies can increase the likelihood of larger lies later.

The project description says dishonesty is studied across emotions, cognition, and institutions, and notes that people can lie more when placed in a competitive setting if everyone has the opportunity to cheat. It also states that individuals may forget past lies more when that amnesia can serve as an excuse not to engage in future morally responsible behavior. This is contextual evidence about mechanisms and conditions related to dishonesty, not a direct test of the slippery-slope claim.

In the 2016 Nature Neuroscience study by Garrett, Lazzaro, Ariely, and Sharot, participants repeatedly made self-serving dishonest estimates, and dishonesty increased across trials while amygdala response decreased. The study is widely cited as evidence for a “slippery slope” mechanism in which repeated small lies can make later, larger lies more likely.

In this interview about the Nature Neuroscience research, the scientist explains: "we found that people start with small lies and those small lies become bigger and bigger and bigger" and "as the lies become bigger the emotional response in the brain become smaller." Later she notes that "when people lie more and more and more the amygdala sensitivity to dishonesty goes down" and that "the more [the amygdala response] dropped the more likely the participant was to tell bigger lies next time they got a chance." She concludes that "it looks like our brain adapts to lying in a similar way as we adapt to other things," explicitly linking neural adaptation to the escalation from small to larger lies.

This psychology essay discusses broader effects of everyday dishonesty, noting that "psychologists call this 'deceiver’s distrust'. The reasoning goes like this: 'If I’m lying, other people are probably lying to me too.' You start to distrust others, ironically, because you are being dishonest." It further observes that "other research suggests that secrets and lies result in less social connection, and a sense of alienation from others" and that "people who tell more lies also report feeling more lonely – even when their lies were told for the express purpose of saving relationships." While not focused on neural desensitization, it provides evidence that repeated lying, including small 'white lies', can have escalating negative interpersonal and psychological consequences.

This longitudinal study, though about violence rather than lying, illustrates a general mechanism of emotional desensitization leading to more severe behavior. The authors report 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 later, but "a small subset of youth (about 10% in this sample) who have been exposed to high levels of violence as early adolescents, experience lower internalizing distress and in turn commit more violence five years later." They conclude that "high levels of violence exposure... lead to emotional desensitization" and that this reduced distress predicts increased violent behavior, exemplifying how repeated exposure can blunt emotional responses and increase the likelihood of more extreme actions.

The authors reported empirical evidence that dishonesty gradually increases with repetition. They wrote that reduced amygdala sensitivity to dishonesty on a current decision relative to the previous one predicts the magnitude of escalation of self-serving dishonesty on the next decision.

The paper states that recent experiments suggest dishonesty can escalate from small levels to ever-larger ones along a slippery slope. It also says that when a self-serving condition holds, decisions with a high probability of being dishonest take less time and involve less hesitation. This is a secondary-hosted version of the research rather than the original journal page.