EXPECTATION BIAS:

Observers may make systematic errors in measuring and recording observations so that they concur with prior expectations¹. This bias may occur most frequently with inexperienced observers; who lack the information or ability to understand why measurements may be different than previous expectations. Essentially this bias describes a human tendency to criticize, or question phenomena, that that we know are wrong/different, but avoid criticizing or questioning phenomena which we are unsure are wrong. Further, this may be analogous to when reviewers of scientific papers, tend to avoid criticizing certain points of a paper (i.e. leave no comment), if they feel they do not have sufficient information or knowledge in the area to criticize it, even if the issues seem ‘suspicious’. Also see: Information Bias, and The Results We’ve All Been Waiting For Bias.

Reference:

1. Sackett DL. Bias in analytic research. J Chronic Dis. 1979;32 (1-2):51-63. (Link to Reference)