Blatantly false news increases belief in news that is merely implausible

Contributions

• Documents a novel contrast effect in misinformation: high prevalence of blatantly false news lowers the plausibility threshold for judging other claims as believable.
• Demonstrates the effect across both active evaluation (Studies 1–2) and passive reading (Studies 3a–3b) conditions, suggesting robustness to how people consume news.
• Tests whether the effect generalizes when plausibility and accuracy are decoupled (Study 4), showing the mechanism operates on subjective plausibility rather than objective truth.
• Provides evidence that the effect is not driven by media discernment ability, but by shifts in internal baseline judgments of what seems plausible.

Method

Five preregistered studies varied in design:

Studies 1–2: Participants randomly assigned to low, moderate, or high implausibility conditions were exposed to news headlines and rated whether each was plausible. In Study 1, headlines were hypothetical (n=419). In Study 2, headlines were real, fact-checked news (n=599), allowing orthogonal manipulation of plausibility and actual truth.

Studies 3a–3b: Participants passively read the same headlines from Study 2 without active evaluation, then judged truthfulness of a subset. This tested whether the effect requires active deliberation (n=3,129 total).

Study 4: Reanalysis of Orchinik et al. (2023) data (n=1,455) in which plausibility and truth were positively correlated, mimicking real social media conditions where plausible claims are more likely true.

All studies used binomial generalized linear mixed models with random intercepts for participants and headlines.

Results

Studies 1–3b: Across all conditions, high prevalence of implausible headlines significantly reduced the plausibility threshold for judging other headlines as believable (e.g., Study 2: b = 0.89, SE = 0.28, p < 0.001). Compared to low-implausibility conditions, people in high-implausibility conditions rated ambiguous and moderately false headlines as more plausible. The effect persisted in passive-reading conditions and across active/passive meta-analysis (OR = 2.39, p < 0.001).

Study 4: When plausibility and truth were linked (realistic scenario), the high-implausibility condition still produced a significant interaction at the initial habituation phase. Over 50 trials, the effect was strongest for ambiguously plausible headlines but weakened for clearly implausible or plausible ones.

Media truth discernment: Across Studies 2–3b, there was no consistent relationship between plausibility condition and ability to discriminate true from false headlines, ruling out changes in media literacy as the mechanism.

Notes

Strength: Large, preregistered sample (5,476 total) across multiple designs. Clean orthogonal manipulation of plausibility and truth in Studies 2 and 4. Passive-reading replication (Studies 3a–3b) strengthens claims about real-world relevance.

Weakness: Studies use isolated headline evaluation; real social media consumption involves social signals, recommendation algorithms, and repeated exposures that may modulate or compound the effect. Study 4's reanalysis uses secondary data, limiting power over the prevalence manipulation.

Important implication: Even individuals who can reliably identify blatantly false content may become more susceptible to subtler falsehoods when exposed to high-prevalence obviously false claims. This has consequences for platforms trying to surface or label false content—removing obvious falsehoods might inadvertently benefit moderately false claims by narrowing people's conception of what seems implausible.