In order to validate external perceptions there are clear criteria in the natural sciences as to what is known and what is not known. In psychology we are dealing with internal perceptions, where the boundary between knowledge and non-knowledge cannot be so clearly defined due to the subjectivity of the observer. However, during the past hundred years, a culture of validation of internal perceptions has been developed in psychoanalysis and other psychotherapies by means of controlled self experience and supervision. As a result the quality and value of an internal perception can be quite unequivocally characterized thus allowing a differentiation to that which is not known. This culture of reflexive validation is particularly significant in the field of prenatal psychology which is concerned with the investigation of the offshoots of prenatal and perinatal experiences. Due to the recency of these observations it is particularly important to differentiate clearly between knowledge and non-knowledge.