Social desirability bias is the tendency of respondents to answer questions in a manner that will be viewed favorably by others. It can take the form of over-reporting good behavior or under-reporting bad behavior. The tendency poses a serious problem with conducting research with self-reports, especially questionnaires. Topics of special concern are self-reports of abilities, personality, sexual behavior, and drug use.
When confronted with the question ‘How often do you masturbate?,’ for example, respondents may be pressured by the societal taboo against masturbation, and either under-report the frequency or avoid answering the question. Therefore the mean rates of masturbation derived from self-report surveys are likely to be severe underestimates.
When confronted with the question, ‘Do you use drugs/illicit substances?’ the respondent may be influenced by the fact that controlled substances, including the more commonly-used marijuana, are generally illegal. Respondents may feel pressured to deny any drug use or rationalize it, e.g., ‘I only smoke marijuana when my friends are around.’ The bias can also influence reports of number of sexual partners. In fact, the bias may operate in opposite directions for different subgroups: Whereas men tend to inflate the numbers, women tend to underestimate theirs. In either case, the mean reports from both groups are likely to be distorted by social desirability bias.
Other topics that are sensitive to social desirability bias: Personal income and earnings, often inflated when low and deflated when high; Feelings of low self-worth and/or powerlessness, often denied; Excretory functions, often approached uncomfortably, if discussed at all; Compliance with medicinal dosing schedules, often inflated; Religion, often either avoided or uncomfortably approached; Patriotism, either inflated or, if denied, done so with a fear of other party’s judgement; Bigotry and intolerance, often denied, even if it exists within the responder; Intellectual achievements, often inflated; Physical appearance, either inflated or deflated; Acts of real or imagined physical violence, often denied; Indicators of charity or ‘benevolence,’ often inflated; and Illegal acts, often denied.
The fact that people differ in their tendency to engage in socially desirable responding (SDR) is a special concern to those measuring individual differences with self-reports. Individual differences in SDR make it difficult to distinguish those people with good traits who are responding factually from those distorting their answers in a positive direction. When SDR cannot be eliminated, researchers may resort to evaluating the tendency and then control for it. A separate measure of SDR must be administered together with the primary measure (test or interview) aimed at the subject matter of the research/investigation.
The key assumption is that respondents who answer in a socially desirable manner on that scale are also responding desirably to all self reports throughout the study. In some cases the entire questionnaire package from high scoring respondents may simply be discarded. Alternatively, respondents’ answers on the primary questionnaires may be statistically adjusted commensurate with their SDR tendencies. The major concern with SDR scales is that they confound style with content. After all, people actually differ in the degree to which they possess desirable traits (e.g., nuns versus criminals). Consequently, measures of social desirability confound true differences with social-desirability bias.
‘Extreme response bias’ (ERB) takes the form of exaggerated extremity preference, e.g. for ‘1’ or ‘7’ on 7-point scales. Its converse, ‘moderacy bias’ entails a preference for middle range (or midpoint) responses (e.g. 3-5 on 7-point scales). ‘Acquiescence’ is the tendency to prefer the higher ratings over lower ratings, whatever the content of the question.