Headline bias is the tendency for a headline to shape a reader's understanding of a story even when the body of that story contradicts it.
Researchers at the University of Western Australia tested the effect directly and found that a misleading headline skewed participants' reading of an entire news article, and that the distortion survived exposure to the correcting detail further down. Misinformation delivered in a headline proved unusually resistant to later correction, and the pattern held for factual reports and opinion pieces alike.
The mechanism is anchoring plus primacy. The headline is processed first, establishes an interpretive frame, and everything after it is read as elaboration on that frame rather than as contradiction of it — the reader is not weighing two claims but fitting new detail into a conclusion already formed. 📝Gestalt Psychology describes the same underlying tendency to resolve incoming parts into a whole that has already taken shape.
The finding generalizes well beyond journalism to any message whose opening element is read before the rest: email subject lines, push notifications, link previews, the first line of a post. Setting the frame correctly costs less than retracting it afterward, because retraction rarely fully lands.