The intentional misleading of a subject about the nature of the study. Deception increases ethical concerns and should be used with discretion, because it interferes with the ability of the subject to give informed consent. Misleading or omitted information might include the purpose of the research, the role of the researcher, or what procedures in the study are actually experimental. The IRB recognizes that deception or concealment may be necessary for certain types of behavioral research. Because people act differently depending on circumstances, full knowledge by the subject might bias the results in some cases.