Peterson, C., & Grant, M. (2001). Forced-choice: Are forensic interviewers asking the right questions? Canadian Journal of Behavioural Science, 33, 118-127.
In spite of exhortations to the contrary, forensic interviewers typically ask forced-choice questions, especially yes/no and multiple-choice. In this study, older and younger preschoolers' responses to yes/no and multiple-choice questions were compared. For yes/no questions, half were correctly answered by 'yes' and half by 'no.' For 2-option multiple-choice questions, the first option was correct for a third of them, the second option was correct for another third, and neither option was correct for the remainder. Half the children were instructed they could say "I don't know." Both older and younger preschoolers demonstrated a response bias toward saying 'yes' to yes/no questions; they did not exhibit response biases for multiple-choice questions, choosing the two given options equivalently often. When neither option was correct, they more frequently said "I don't know", especially younger preschoolers. "I don't know" was almost never given in response to yes/no questions. Furthermore, instructions allowing "I don't know" had no effect. These results have implications for forensic interviews; they suggest that responses to yes/no questions are more unreliable and information from them more suspect than responses to multiple-choice questions.