“A mental disorder of infancy or early childhood (beginning before age 5 years) characterized by disturbed and developmentally inappropriate patterns of social relating, not resulting from mental retardation or pervasive developmental disorder, evidenced either by a persistent failure to initiate or respond appropriately in social interactions (inhibited type), or by indiscriminate sociability without appropriate selective attachments (uninhibited type). By definition, there must also be evidence of pathogenic care, assumed to be responsible for the disturbed social relating, in the form of persistent disregard for the child’s basic emotional or physical needs or repeated changes in major attachment figures.”
Excerpted from: Colman, Andrew M., ed. Oxford Dictionary of Psychology. New York: Oxford University Press, 2003.