Writing a headline that implies something more dramatic, certain, or alarming than the article itself supports — exploiting the fact that most people don't read beyond the first paragraph.
Headline: "New study links popular sweetener to cancer." Paragraph 3: "Researchers observed a slight statistical association in a mouse model at doses equivalent to 400 cans of soda per day. The authors caution that no causal link has been established in humans." The headline is not technically false — there is a study, and it does find a link. But 90% of readers will share the headline having never encountered the qualification.
Comprehension is effort. Most people engage with headlines, scan the first paragraph, and move on — especially in high-volume information environments. Headlines are optimized for sharing, not accuracy. The mismatch is often intentional, because alarm drives clicks.
Always read the methodology section before accepting a "study says" claim. Watch for headlines with confident declarative statements about research that, when read closely, show association not causation, animal not human models, or heavily qualified findings.