Correlates of mother-infant attachment : a meta-analysis

Abstract

A meta-analysis was conducted to review and integrate the findings of the mother-infant attachment literature. Standardizing differences for secure and anxiously attached infants from 89 studies yielded 809 outcome values. Across all variables and study types, 90% of the effects were positive, and the average effect size was +0.63, indicating that securely attached infants display more favorable outcomes than do those who are anxiously attached. Maternal characteristics were two-thirds of a standard deviation greater for secure than for anxiously attached infants. Infant attributes overall demonstrated a mean effect size of 0.59, with physical aspects elevated for securely attached infants 0.03, temperament 0.55, cognitive/intellectual aspects 0.47, social 0.78, and emotional 0.66. Mother-infant interaction and behaviors of the mother toward her infant and of the infant toward the mother were more positive for securely attached infants, demonstrating effect sizes of 0.70, 0.66, and 0 .83, respectively. Situations were more favorable for securely attached infants by one-half of a standard deviation. Antecedent studies showed an effect size of +0.77. Concurrent measurement of attachment and its correlated variables produced an effect size of +0.39. Security of mother-infant attachment was predictive of favorable outcomes with a resultant effect size value of +0.71. Many of the methodological factors coded were determined to contribute to the findings of this meta-analysis. Sex and race of the subjects, source and time of publication, sample size, type of measure, setting, study type, subdivision (or not) of the anxious attachment group, number of contrasts, test statistic used, significance level of the result, and training of the author were related to effect size, either practically, statistically, or both. Subjects' ages and sociometric status statement (or not) of attachment group sizes, and technique were unrelated...