Evaluate sources by searching about them, not by reading them — lateral beats vertical reading
Apply lateral reading by immediately opening new tabs to search for independent information about a source rather than evaluating the source by reading the source itself, because external assessment outperforms internal coherence checking.
Why This Is a Rule
Wineburg et al.'s research on how professional fact-checkers evaluate sources revealed a counterintuitive finding: experts spend less time reading the source itself and more time searching for information about the source from independent parties. Novices do the opposite — they read the source carefully, checking internal coherence, professional appearance, and citation quality. The experts outperform dramatically.
Vertical reading (reading down into the source) evaluates the source by the source's own presentation. A well-designed website with professional language and internal citations looks credible — even when the claims are false. Vertical reading is easily fooled because you're evaluating the source using information the source controls.
Lateral reading (reading across to other sources) evaluates the source by searching for what independent parties say about it. "Who is this author? What do fact-checkers say about this outlet? What do experts in this field say about these claims?" This information is not controlled by the source and provides a more reliable credibility signal.
When This Fires
- When evaluating any new information source you haven't used before
- When a claim seems too good, too alarming, or too convenient to be true
- Before sharing or acting on information from an unfamiliar source
- During any source evaluation where credibility matters for your decision
Common Failure Mode
Spending 10 minutes carefully reading an article to assess credibility, then concluding "it seems well-researched" based on internal coherence. The 10 minutes would have been better spent on 2 minutes of lateral reading: searching the author's name, the publication's reputation, and the specific claim across independent sources.
The Protocol
When evaluating a new source: (1) Do NOT start by reading the source carefully. (2) Open new tabs and search: who is the author? What is the publication's reputation? What do independent fact-checkers or domain experts say about this claim? (3) Spend 2-3 minutes on lateral assessment before deciding whether the source merits vertical reading. (4) Only if lateral reading confirms credibility → invest time reading the source vertically for content. This sequence saves time (quickly filtering unreliable sources) and improves accuracy (evaluating by external signal rather than internal presentation).