The PAA was devised by P.Crittenden for the purpose of assessing patterns of attachment in 18-month to 5-year-old children. Like the SSP it involves an observation which is then coded. The classifications include all the SSP categories plus patterns that develop during the second year of life. The three basic strategies for negotiating interpersonal relationships are modified to fit preschoolers and the patterns are renamed "secure/balanced", or Type B, "defended", or Type A and "coercive" or Type C. It is also intended to be able to distinguish the unendangered from the endangered compulsive and obsessive subpatterns that may have implications for emotional and behavioral development.