Day care during infancy is associated with "deviations" in the expected course of emotional development. Infants placed in twenty or more hours of day care per week avoid their mothers and are insecurely attached; some have attachment problems with both mothers and fathers. Children placed in day care receive less adult attention, communicate less, receive and display less affection, are more aggressive, and are less responsive to adults. Compared with children who were cared for by their mothers as preschoolers, third-graders who were placed in day care as preschoolers are viewed more negatively by their peers, have lower academic grades, and demonstrate poorer study skills.