Lynn Hasher

Lynn Hasher

Lynn Hasher is a cognitive psychologist who works on memory and cognition and the first author of the 1977 paper that reported the illusory truth effect, with David Goldstein and Thomas Toppino. That paper found that statements repeated across sessions were rated with more confidence than statements seen once, whether they were true or false.

Who they are

Hasher is a cognitive psychologist whose research concerns memory and cognition. Her best-known contribution on this site is the 1977 paper.

The 1977 paper, with Goldstein and Toppino, appeared in the Journal of Verbal Learning and Verbal Behavior. It gave the field a design that has been reused for decades: participants judge obscure statements, some of which return in later sessions, and the repeated ones gain in rated validity.

Key papers

Hasher, L., Goldstein, D., & Toppino, T. (1977). Frequency and the conference of referential validity. Journal of Verbal Learning and Verbal Behavior, 16(1), 107-112. doi:10.1016/s0022-5371(77)80012-1. Participants judged 60 plausible but obscure statements across three sessions two weeks apart, with some statements repeated in every session. Confidence rose for the repeated statements, true or false, and the authors concluded that frequency of encounter is one of the factors that decide perceived validity.

Key ideas

The illusory truth effect: repeated statements are rated as more likely to be true than new ones. A 2026 meta-analysis of 182 studies reported a small but robust pooled effect.

The link to cognitive ease: Daniel Kahneman lists repeated experience as one of four sources of cognitive ease, and the 1977 design is the laboratory form of it.

Sources

  1. Hasher, L., Goldstein, D., & Toppino, T. (1977). Frequency and the conference of referential validity. Journal of Verbal Learning and Verbal Behavior, 16(1), 107-112. doi:10.1016/s0022-5371(77)80012-1
  2. Ye, Attali, Ghazi, Cachia, Cassotti and Borst (2026). Systematic review and meta-analysis of the evidence for an illusory truth effect and its determinants. Nature Communications. doi:10.1038/s41467-026-70041-x
  3. Kahneman, D. (2011). Thinking, Fast and Slow.