A recent study published in Current Psychology suggests that people are more likely to believe false information when it comes from someone who ignores the truth rather than a liar who actively tries to deceive. The research indicates that repeating statements made by someone indifferent to facts heavily increases how truthful those statements feel to readers. These findings provide evidence that casual disregard for reality poses a uniquely potent threat to public knowledge and belief.
The digital age makes tracking misinformation increasingly difficult. Information often spreads not just through intentional deception, but through a behavior known in psychology as bullshitting. In academic terms, a liar is someone who knows the truth and intentionally tries to mislead an audience. A bullshitter, on the other hand, communicates with little to no regard for the truth, evidence, or established facts.
A statement made by a bullshitter might happen to be true, or it might be false. The defining characteristic is the speaker’s total indifference to reality. Because bullshitters do not actively try to hide a specific truth, people often judge them less harshly than they judge outright liars.
John V. Petrocelli, a psychology professor at Wake Forest University and author of the book The Life-Changing Science of Detecting Bullshit, wanted to test the real-world impact of this behavior. He noted that philosopher Harry Frankfurt proposed the insidious bullshit hypothesis in 1986. This idea suggests that society’s tolerance for bullshitting actually creates more long-term harm to public knowledge than lying.
Past research supports this distinction. In a 2023 study, Petrocelli and his colleagues explored how untrustworthy sources influence consumer attitudes over time. Participants read an advertisement for a fictitious gluten-free pizza and then learned the advertiser was either a known liar or a known bullshitter.
After a two-week delay, participants who had been warned about the bullshitter reported more positive attitudes toward the pizza than those warned about the liar. This demonstrated a “sleeper effect,” where the deceptive influence of the bullshitter actually grew stronger over time. The researchers also found that people possess a higher “dismissal readiness” for lies, meaning they find it easier to entirely reject a known lie than a statement of bullshit.
“We’d already found that people evaluate bullshitting less harshly than lying, consistent with Frankfurt’s (1986) essay,” Petrocelli explained. “But the harder question Frankfurt raised, and one almost nobody had tested empirically, was whether bullshit actually does more damage to what people believe, precisely because it doesn’t trigger the same skepticism a known lie does.”
To test this idea further, researchers examined how bullshitting interacts with the illusory truth effect. The illusory truth effect is a psychological phenomenon where people tend to believe false information is correct simply after hearing it multiple times. When the human brain encounters a repeated statement, it processes that information more easily, and people often mistake this mental ease for actual truth.
Scientists wanted to see if knowing the source of a claim changes this effect. “The illusory truth effect literature gave me a clean, well-validated paradigm to test that consequence directly, rather than just people’s attitudes about bullshitting,” Petrocelli said. If a person knows a statement comes from a bullshitter rather than a liar, they might not filter the repeated information as strictly.
To investigate these dynamics, the authors designed a series of three experiments. In the first experiment, 204 undergraduate students evaluated 42 different statements. Half of these statements were factual, and half were completely false.
The participants were told the statements came from either an average person, a known liar, or a known bullshitter. The researchers provided specific definitions of a liar and a bullshitter to the participants to ensure they understood the difference. The students then rated how likely each statement was to be true on an 11-point scale.
The data showed that participants rated statements from an alleged bullshitter as more truthful than the exact same statements made by an alleged liar. The average person was trusted the most, but the bullshitter was trusted significantly more than the liar. This initial finding shows people naturally assign a higher likelihood of truth to bullshitting than they do to intentional lies.
The specific terms used to describe the sources were not the main driver of these results. “Just that the labels themselves turned out to matter less than we expected, it wasn’t simply that ‘bullshitter’ sounds better than ‘liar’,” Petrocelli said. “When we controlled for the base rate of false statements in Experiment 3 and gave very explicit, careful definitions of what the source’s instructions were, the effect held up.”
Petrocelli added that this consistency was reassuring. “That gives me more confidence this is really tracking something about how people process source-indifference to truth, not just a reaction to a loaded word,” he explained. The researchers then moved to test how this baseline trust interacts with repeated exposure in a second experiment.
In the second experiment, 293 students participated in a test of the illusory truth effect. The researchers exposed participants to 66 statements and asked them to rate how interesting they were. This served as an initial exposure phase, where some statements appeared once, and some appeared twice.
Before the final truth rating task, the authors separated the participants into different groups. One group was told the author of the statements was instructed to include some obvious lies. Another group was told the author was instructed to include statements with no regard for the truth.
The scientists also manipulated when the participants received a warning about the false information. Half the participants were warned before they read any statements during the initial phase. The other half read the statements first and were warned only before the final truth rating task.
During the final task, everyone rated the truthfulness of 88 statements on a six-point scale. These included a mix of entirely new claims and the repeated claims from the first phase. The researchers then compared how the different warnings affected the students’ beliefs.
The results revealed that forewarning people about falsity before they read the statements reduced the illusory truth effect across all groups. However, when the warning came after the initial exposure, a major difference emerged. Participants in the liar and control groups successfully corrected their judgments, recognizing the false statements as untrue.
In contrast, participants in the bullshitter group still fell for the illusory truth effect. Even after learning the author had no regard for the truth, these students rated the repeated false statements as highly truthful. The repetition of the bullshit claims successfully tricked their minds into believing the statements.
Petrocelli found this specific dynamic particularly intriguing. “The most striking pattern to me was that forewarning worked very differently depending on timing,” he said. “When people were warned before exposure that some information might be bullshit or lies, the illusory truth effect was largely neutralized across the board.”
The delayed warning produced an entirely different response. “But when people only learned after the fact that they’d been exposed to bullshit, the effect not only persisted for bullshit, it was the strongest condition in the whole design,” Petrocelli noted. Lies and honest control claims actually got corrected downward once people learned the truth after exposure.
“That asymmetry, corrective efforts working for lies but seemingly backfiring or simply not working for bullshit, was the clearest empirical signature of insidiousness we could have hoped for,” Petrocelli explained. To confirm these patterns, the researchers conducted a third experiment with 318 students. The setup was nearly identical to the second experiment, but with a strict condition to ensure the results were not just based on assumptions about lying frequencies.
They explicitly told participants that exactly half of the statements were false, lies, or bullshit, depending on the assigned group. This held the frequency of deception completely equal across all scenarios. The authors found the exact same pattern as the previous test, providing evidence that repeated exposure to truth-indifferent claims bypasses critical thinking.
These outcomes suggest that recognizing a source as a liar stops the brain from linking repetition to truth, but recognizing a source as a bullshitter fails to put up the same mental blockade. Petrocelli highlighted how this tendency leaves people vulnerable. “The instinct to relax your guard around someone who’s ‘just talking out of their hat’ rather than deliberately lying to you is exactly backwards,” he explained.
“A known liar’s claims get flagged and rejected; a bullshitter’s claims, because they’re not certainly false, slide by with much less resistance, and repetition alone makes them feel truer over time,” Petrocelli said. He suggested that people change how they evaluate everyday conversations. “If anything, the practical takeaway is: don’t just ask ‘is this person lying to me,’ ask ‘does this person actually know or care whether this is true,’ and treat repeated exposure to indifferent talk with at least as much scrutiny as you’d give a claim you know to be contested,” he recommended.
Recognizing the boundaries of this study helps place the findings into proper context. Petrocelli pointed out two main caveats regarding the research. “First, our operationalization is narrow: we tested one specific cognitive manifestation of insidiousness, the magnitude of the illusory truth effect under repetition, not Frankfurt’s full philosophical claim about bullshit’s corrosive effect on public discourse generally,” he explained.
The second limitation involves how the sources were presented to the participants. “Our manipulation relied on labeling someone a ‘bullshitter’ or ‘liar’ via source instructions, not on demonstrably truth-indifferent behavior itself,” Petrocelli noted. “So strictly speaking, these findings are about the effects of the label and its associated expectations, and future work really needs designs where bullshit is behaviorally instantiated rather than just described.”
Future investigations will likely focus on expanding these initial discoveries into more complex scenarios. The current research relied on neutral, trivia-style statements, but real-world misinformation often centers around highly emotional topics. “One is moving from neutral trivia statements to emotionally charged, real-world content, political claims, health misinformation, since motivated reasoning could plausibly amplify or dampen these effects,” Petrocelli said of his next steps.
He also plans to test whether the effect holds when people are not explicitly warned about a source’s intentions. “And longer-term, we want to push toward interventions, could platforms or media literacy programs actually teach people to detect truth-indifference specifically, as opposed to just teaching general fact-checking or lie-detection skills, which our work suggests may not transfer well to bullshit?” he added.
The study, “When fools have greater influence than liars: testing the insidious bullshit hypothesis with the illusory truth effect,” was authored by John V. Petrocelli, Elijah N. Rice, and Joseph M. Curran.