Response biases in interviews of individuals with limited mental ability.

The validity of responses by individuals with mental retardation during interviews is threatened by a number of biases. Acquiescence (the disposition to answer 'yes' regardless of the question asked) is a commonly observed response bias committed by respondents to questionnaires and interviews, and this disposition is significantly more pronounced when persons of low status are questioned by high-status interviewers. Research on the acquiescence bias suggests that it can be reduced in mentally retarded respondents by replacing the usual 'yes/no' question format with an 'either/or' format. Enhancing the either/or choices with accompanying picture representations of each choice is beneficial in increasing mentally retarded subjects' responding and in reducing their tendency to choose the latter of two either/or choices. 'Nay-saying' (the disposition to say 'no' regardless of the question asked), while less common than 'yea-saying' (i.e. than acquiescence), has also been noted in response to certain question formats and taboo topics. This review implies that the validity of an interview with respondents of limited intelligence depends greatly on the format of its questions.