This was done in the McMartin preschool case. The biased interviews were contaminated by leading suggestive and coercive questions. These questions presuppose that something was done and further presuppose that the father was in fact the actor involved thereby establishing him as guilty of the act. The effect of confirmatory bias through leading, suggestive and coercive questioning can typically not be recognized by the interviewer. The children will conform their responses and thinking to the clues which they pick up from the adult interviewer.
Confirmatory bias invites the child to conform the reports to what others have said.
What occurs is that the more often the topic is broached with the children or the child in question, the more validity which is given the child by the interviewer as to the allegations themselves. Repeated questioning effect is also generally not the only contaminant. In other words the presumed existence of confirmatory facts is suggested by the interviewer based upon how the question is asked. Whether they are by way of body language, linguistic markers or other suggestive or leading methods. It is generally understood that after the interview the therapist cannot recall accurately what the therapist did.