Children in daycare experience fewer one-to-one interactions with adults, which is negative for IQ in families where such interactions are of higher quality; reduction in IQ increases with family income

Ichino, A., Fort, M., & Zanella, G. (2019). Cognitive and Non-Cognitive Costs of Daycare 0-2 for Children in Advantaged Families. Journal of Political Economy, May 2019. doi:10.1086/704075

Abstract: Exploiting admission thresholds to the Bologna daycare system, we show using RDD that one additional daycare month at age 0–2 reduces IQ by 0.5% (4.7% of a s.d.) at age8–14 in a relatively affluent population. The magnitude of this negative effect increases with family income. Similar negative impacts are found for personality traits. These findings are consistent with the hypothesis from psychology that children in daycare experience fewer one-to-one interactions with adults, with negative effects in families where such interactions are of higher quality. We embed this hypothesis in a model that lends structure to our RDD.

JEL-Code: J13, I20, I28, H75
Keywords: daycare, childcare, child development, cognitive skills, personality