The authors propose to re-evaluate Tustin's thesis using both the extensive clinical material of a child with an autistic disorder [PDD], and current research on infant development. Beebe's concept of ‘interaction structure’ that could be inferred from the fifth month of life using face-to-face research data is used for postulating a dialogic space that would be generated inside such structure, allowing for definition of self and other in a relationship. If such space is collapsed, the other would be a threat of annihilation for the self, thus it should be avoided or merged with, which could explain the systematic avoidance of the not-me in autistic states. The authors stress that these ideas are just one alternate model, among several, that seems to be able to explain the patient's deviant development.