For authors and funding organizations, peer review provides an important veneer of respectability. Findings published in a famous journal take on the aura of the journal's reputation. This may be well founded � some journals invest a lot of effort in selecting, checking and publishing articles. Yet, even the most-respected journals have been caught out and, despite extensive peer review, have ended up publishing fraudulent or seriously flawed material.

Confirmatory bias is the tendency to emphasize and believe experiences that support one's views and to ignore or discredit those that do not. The effects of this tendency have been repeatedly documented in clinical research. However, its ramifications for the behavior of scientists have yet to be adequately explored. For example, although publication is a critical element in determining the contribution and impact of scientific findings, little research attention has been devoted to the variables operative in journal review policies. In the present study, 7S journal reviewers were asked to referee manuscripts that described identical experimental procedures but which reported positive, negative, mixed, or no results. In addition to showing poor interrater agreement, reviewers were strongly biased against manuscripts that reported results contrary to their theoretical perspective. The implications of these findings for epistemology and the peer review system are briefly addressed.

One study found that the vast majority of scientists drawn from a national sample showed a strong preference for "confirmatory" experiments (Mahoney & Kimper, 1976). Over half of these scientists did not even recognize disconfirmation (modus tollens) as a valid reasoning form! In another study the logical reasoning skills of 30 scientists were compared to those of 15 relatively uneducated Protestant ministers (Mahoney & DeMonbreun, 1977). Where there were performance differences, they tended to favor the ministers. Confirmatory bias was prevalent in both groups, but the ministers used disconfirmatory logic almost twice as often as the scientists did.