 While it was originally developed by Dr. Mary Dozier at the University of Delaware for caregivers of infants ages 6–24 months (ABC-Infant), it has since been expanded to include toddlers ages 24–48 months (ABC-Toddler).This was an attempt to collect and synthesise the data to try to come to "evidence-based" conclusions on the best intervention practices for attachment in infants.There were four hypotheses