In addition to the notion of "breaking through" defence mechanisms, other metaphors were adopted by practitioners relating to the supposed effects of early deprivation, abuse or neglect on the child's ability to form relationships. These included the idea of the child's development being "frozen" and treatment being required to "unfreeze" development. Practitioners of holding therapy also added some components of Bowlby's attachment theory and the therapy came to be known as attachment therapy. Language from attachment theory is used but descriptions of the practices contain ideas and techniques based on misapplied metaphors deriving from Zaslow and psychoanalysis, not attachment theory. According to Prior and Glaser "there is no empirical evidence to support Zaslow's theory. The concept of suppressed rage has, nevertheless, continued to be a central focus explaining the children's behavior."