The attachment development theory is to analyze how attachment in infancy can influence the development of a child. Bowlby and Ainsworth have aided in a good portion of this theory. Especially with their research being focused on infancy, and attachment in child development. But they're just theories and after all, theories are meant to be tested.
Bowlby's theory, which simply proves that a child shows attachment to a person; usually their mother, in situations when they are needed the most, such as the child being frightened, tired, or ill. Bowlby believed that attachment commences at infancy and perpetuates throughout life. That several innate behavioral control systems are needed for survival and procreation. Bowlby's theory goes on the fact that children need their parents until they slowly venture off on their own. Ainsworth takes it to the next level with the "Strange Situation" as if Bowlby's theory was the foundation. As Ainsworth and Bowlby's theories correlate, Ainsworth's research can help prove both. "The strange Situation" was a research model that splits attachment up into three types: secure, avoidant, and resistant. The secure type is when an infant seeks protection or comfort from their mother and receives care consistently. The mother is customarily rated as doting and affectionate. The avoidant type is when the infant inclines to pull away from their mother or ignore her. The mother is customarily rated as repudiating the child's annexation comportment. The resistant type is when the infant inclines to stay proximate to their mother. The mother is customarily rated as being inconsistently erratic in their care.
Although Bowlby's and Ainsworth's theory could be proven as true, there should be more too it. The attachment a child has with a different figure in their lives, other than their mother. How is that comparably different, from their father figure or their siblings, can it be the same based on their relationship...