Just a quick evaluation nugget for you. Fraley and Spieker (2003) have found that classifying infants by type may not be accurate. The researchers looked at data recorded for over 1000 children involved in the NICHD study. The data had been collected from observations made in the strange situation. The re-analysis showed that variations in patterns was largely continuous i.e. children didn’t possess a cluster of characteristics typical of one particular category. Instead they differed along various dimensions such as response to mother’s return.This challenges any research which has categorised children as secure, insecure-resistant or insecure-avoidant because such exclusive categories don’t represent reality, according to this research. Fraley, R. C., & Spieker, S. J. (2003). Are infant attachment patterns continuously or categorically distributed? A taxometric analysis of strange situation behavior. Developmental Psychology, 39, 387-404.