Mark Lepper
American psychologist
Mark R. Lepper (born December 5, 1944) is the Albert Ray Lang Professor of psychology (emeritus) at Stanford University, and a leading theorist in social psychology. He is particularly known for his research on attribution theory and confirmation bias, and for his collaborations with Lee Ross.
Life
Lepper is primarily responsible for the elucidation of the overjustification effect, alongside Richard Nisbett.
With frequent collaborator Lee Ross, and Robert Vallone, he authored the first study to identify the hostile media effect. With Ross and Charles Lord he also authored an important study on attitude change and what is now called disconfirmation bias. With Lord he later theorized attitude representation theory. He has also worked with Thomas Gilovich and Merrill Carlsmith.
Lepper attended Stanford University as an undergraduate, earning a B.A. with great distinction in psychology in 1966. He subsequently earned a Ph.D. in Social and Developmental Psychology at Yale University in 1970, returning to Stanford in 1971 as an assistant professor. Lepper became a full professor of psychology and, by courtesy, of education in 1982, and has since served as chairman of the department of psychology between 1990 and 1994, and again after 2000.
Begin with the source’s own compact description: “Mark Lepper” is american psychologist. The dossier treats that line as a proposition to test through Mark, Lepper and American, not as a finished interpretation.
Why this record matters
The phrase “american psychologist” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Aug 29, 2026. The linked authority identifier is Q6768562. VIAF identifies the subject as 70186625. The Library of Congress control number is n78044428. 1 of 3 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1944, 1966, 1970 and 1971.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Mark Lepper”, its source revision and the description used here.
- Expand the search: follow Mark Lepper primary sources, Mark Lepper archive and Mark research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Mark Lepper”?
- Which institution is responsible for the underlying evidence?
- Which cited source is closest to the event, object or claim?
Search terms from this dossier
This entry incorporates text from “Mark Lepper” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.