The Challenge of Measuring Relationships
Bowlby's theory can be boiled down to two propositions: the history of children's interactions with early caretakers shapes the quality of their attachment relationships (whether they become secure); and, these attachment relationships then become the foundation for later personality development. But for theory and speculation to truly become science, there must a means of measurement, something that Freud and his successors had largely ignored. The practical challenge for researchers testing Bowlby's propositions about development was to find a method for capturing something seemingly elusive. After all, how can you possibly measure a relationship to determine whether it's affecting a child's development?
While it's relatively easy to measure how often an infant seeks contact, or whether it cries when someone approaches, none of these factors really capture the quality of the connection the young child experiences. If secure attachment isn't an inborn trait but a quality of the relationship that's being examined, how is this to be defined and measured? The answer to that question has been the key to the growth of the attachment-research literature, and the credit for devising a way to measure attachment goes largely to Mary Ainsworth. A colleague of Bowlby's at the Tavistock Institute, Ainsworth went on to conduct a series of field observations, first in Uganda and then in Baltimore, which ultimately led to the Strange Situation laboratory procedure.
While in Uganda, Ainsworth first developed the hypothesis that "attunement," the sensitive responsiveness to the infant's cues, was the critical factor in determining the type and quality of an infant's attachment, not simply a generalized trait like "warmth." Vigorously playing with an already overly aroused infant wouldn't be attuned parental behavior, while engaging in the same behavior with an infant who needs such stimulation would have a very different relational meaning. Attunement, or sensitivity, requires that the caregiver perceive, make sense of, and respond in a timely and effective manner to the actual moment-to-moment signals sent by the child.
Later, while at Johns Hopkins University in Baltimore, Ainsworth tested her ideas about attachment patterns by putting in 47 hours of painstaking observation with each mother–child pair in her study. She found that when caregivers promptly and effectively responded to young infants' cries, the babies cried less by the end of the first year. The securely attached children had learned that their caregivers were reliable and therefore subtler expressions of their distress and needs would generate responses—they didn't need to be crybabies to get the attention they sought. Infants who develop confidence in their caregivers are securely attached because their caregivers have proven to be reliable.
To create a more practical lab method that wouldn't require so many hours of extended observation, Ainsworth developed the Strange Situation procedure as a way of going beyond measures of simple infant behaviors to capture qualities of the mother-child relationship. In this procedure, the infant and mother enter a toy-filled laboratory setting and are joined by a stranger a few minutes later. The infant then is left with the stranger for three minutes, until the mother returns. Next the infant is left alone briefly, until the mother returns again.
This "strange situation" evokes separation anxiety in the child, which is thought to activate the inborn attachment system. The baby's response to reunion is the factor that determines the "classification" of the attachment relationship. Since a child can have a different attachment category of response with different caregivers, whatever experience the child has had with that particular caregiver will be reflected in how the child responds during their reunion. In this manner, the strange situation is an assessment of a relationship, not a feature or inherent trait of the child.