Infant day-care, attachment, and the "file drawer problem".

The research literature on infant day-care and attachment may be biased by the unavailability of "file drawer" studies, unpublished data showing no statistically significant effects. Replication studies, whether showing an effect or not, are essential to clarify the relation between day-care and attachment. This study of 105 12-month-olds is an attempt to replicate four similar studies summarized and combined by Belsky to show that infants in day-care are at risk for insecure attachment. In the present study, no results were robust enough to emerge consistently, although there was a trend for more negative attachment outcomes to be associated with little or part-time day-care rather than with full-time day-care. In general, the results suggest that the specific measures, definitions of full- and part-time, and statistical techniques used in studies examining the relation between day-care and attachment are likely to affect the outcome of such studies.