A new study, published in the journal Child Development, set out to measure the emotional and physiological responses of new mothers toward their distressed infants in order to identify any factors that might predict an insecure type of attachment, such as infant avoidance and resistance.
Although most infants develop secure attachment relationships with their mothers, about 40 percent of babies establish insecure attachments and are at risk for problems later in life.
Some of these insecurely-attached babies develop what is called insecure-avoidant attachments (minimizing expressing negative emotions and avoiding contact with their mothers when they’re afraid or uncertain), while others develop insecure-resistant attachments (becoming emotionally overwhelmed and inconsolable by their mothers in these circumstances).
“Identifying factors that contribute to infants’ avoidance and resistance is important for developing effective interventions that promote babies’ attachment security, and in turn, positive child development,” said Ashley M. Groh, assistant professor of psychological sciences at the University of Missouri, Columbia, who led the study.
For the study, researchers from the University of Missouri, the University of North Carolina and Pennsylvania State University evaluated an ethnically and economically diverse group of 127 mothers and their infants.
Half of the families were African American and half were European American. Half of the families lived below the 2002 federal poverty line (that is, annual income below $15,000 for a family of three) and half lived above that line.
Researchers analyzed the mothers’ respiration sinus arrhythmia (RSA), or the variability in their heart rate over the breathing cycle, when they interacted with their distressed babies at six months of age.
Decreases in RSA when faced with a challenge, such as a crying baby, reflect better physiological regulation that supports actively coping with that challenge. Researchers also observed how the mothers expressed emotion when they interacted with their distressed infants.
Six months later, when the infants were 12 months old, researchers assessed their attachments to their mothers using the Strange Situation procedure, which involves going through a series of separations and subsequent reunions with their mothers. Research has shown that an infant’s behavior when reunited with his or her mother tells us about the pattern of attachment.
When reunited with their mothers, insecure-avoidant infants ignore their mothers, while insecure-resistant infants become very distressed and simultaneously seek and resist their mothers.
The study findings show that mothers who had smaller decreases in RSA — meaning, less physiological regulation — when they interacted with their distressed infants at six months were more likely to have avoidant infants at 12 months. This type of physiological response might undermine a mother’s ability to cope with her infant’s distress. The baby may view her as a less effective source of comfort and ultimately be less likely to seek her out when upset or uncertain.
Mothers who were more emotionally neutral (versus positive) when their infants were distressed at six months were more likely to have resistant infants at 12 months. This suggests that a mother’s emotionally muted response toward her distressed infant might lead the baby to increase his or her expressions of distress.
“This study provides evidence that we can better understand babies’ and mothers’ experiences in these important encounters when babies need reassurance and support if we consider both the mothers’ emotional response and her physiological regulation in these challenging caregiving contexts,” said Martha Cox, professor of psychology at the University of North Carolina, Chapel Hill.
“The evidence can inform efforts aimed at promoting attachment security. Such efforts might target the specific challenges mothers face when confronted with their babies’ distress.”