Acquiescence bias is a category of response bias in which respondents to a survey have a tendency to agree with all the questions or to indicate a positive connotation. Acquiescence is sometimes referred to as “yea-saying” and is the tendency of a respondent to agree with a statement when in doubt. This particularly is in the case of surveys or questionnaires that employ truisms, such as: “It is better to give than to receive” or “Never a lender nor a borrower be”.

Douglas N. Jackson did a demonstration of acquiescence responding on the California F-scale (a measure of authoritarianism), which contains such truisms. He created a reverse-keyed version of the California F-scale where all the items were the opposite in meaning (see the two previous examples for a pair of such contradictory statements). He administered both the original and reverse-keyed versions of the California F-scale to the same group of respondents. One would expect that the correlation between these two scales to be negative, but there was a high, positive correlation. Jackson interpreted this as evidence of acquiescence responding. Respondents were merely being agreeable to the statements, regardless of the content.

Jackson and Messick, using factor analysis, also demonstrated that the two main factors explaining the majority of response variation on the Minnesota Multiphasic Personality Inventory (MMPI) were for social desirability and acquiescence responding (this would also hold true for the revised MMPI-2).

One approach to dealing with acquiescence responding on surveys and questionnaires is to employ a balance of positively and negatively keyed items in terms of the intended content. For example, in trying to assess depression it would be a good idea to also include items assessing happiness and contentedness, etc. (reversed-keyed items), in addition to the usual depressive content.