Indicating when you do not know the answer: The effect of question format and interviewer knowledge on children's 'don't know' responses

Children are interviewed in a variety of contexts, for example, in the legal setting and in experimental research. In these situations, it is often very important that children indicate when they do not know the answer to a question, rather than guess. In the present experiment, one hundred and forty‐nine 5‐ to 9‐year‐olds witnessed a staged event in one of two conditions. The interviewer was either present at the event (knowledgeable interviewer) or absent from the event (uninformed interviewer). Children were then interviewed using yes/no questions and wh‐questions. Within each type of question, half were answerable based on the information provided; the other half were not answerable (i. e. the correct answer was ‘don't know’). The children performed consistently well with the answerable questions. With the unanswerable questions, there was an effect of format and interviewer knowledge. Children were more likely correctly to indicate that they did not know the answer to an unanswerable wh‐question than an unanswerable yes/no question. Also, children were more likely correctly to say ‘don't know’ to unanswerable questions when the interviewer had been absent from the event.