SHOULD WE TAKE DONT KNOW FOR AN ANSWER

Much attention has been given to the problem of non-attitudes, that is, people expressing opinions while lacking an underlying attitude (false positives). In comparison, the potential problem of false negatives, people with an attitude who decline to express an opinion, has been neglected. Using a survey on nuclear power from Sweden, we examine whether people who answer ''don't know'' but are induced subsequently to give an opinion really have attitudes. The attitudes these people express on follow-up questions predict behavior to a significant extent. This implies that the usual don't know category includes some false negatives, that is, people who really have attitudes but refrain, at least initially, from expressing them.