Aggression and Day Care
Re-interpreting the NICHD results:
Two other findings from the NICHD study that haven't received as much media attention as the aggression/day care link. First, one of the NICHD workers, Sarah Fried, has pointed out that the results related to aggression can be stated differently - the study found that 83% of children who spent 10-30 hours in day care did not show higher levels of aggression. Friedman claims that the study results so far actually tell us very little.
The second finding to consider is that the NICHD data actually showed mothers sensitivity to her child was a better indicator of reported behaviour problems than was time spent in childcare, with more sensitive mothering being linked to fewer problem behaviours. Higher maternal education and family income also predicted lower levels of children's problem behaviours. These findings put the aggression findings in perspective (NICHD 2003). The 20067 data again suggests that children's development is more strongly affected by factors at home than those in day care (Belsky et al., 2007).
Peer Relations and Day Care
The issue of correlation vs cause applies to the peer-relations and day care link. We cannot assume that experiences in day care cause later sociability- we have merely uncovered a link. It might be, for example, that shy and unsociable children have mothers who are also shy and unsociable (because temperament is inherited) and such mothers may prefer to stay at home and care for their children. Therefore, it is more outgoing children who attend day care, which explains why day care children are more sociable.