Carolina de Weerth

Habituation and dishabituation are the most prevalent measures of infant cognitive functioning, and they have reliably been shown to predict later cognitive outcomes. Yet, the exact mechanisms underlying infant habituation and dishabituation are still unclear. To investigate them, we tested 106 8‐month‐old infants on a classic habituation task and a novel visual learning task. We used a hierarchical Bayesian model to identify individual differences in sustained attention, learning performance, processing speed and curiosity from the visual learning task. These factors were then related to habituation and dishabituation. We found that habituation time was related to individual differences in processing speed, while dishabituation was related to curiosity, but only for infants who did not habituate. These results offer novel insights in the mechanisms underlying habituation and serve as proof of concept for hierarchical models as an effective tool to measure individual differences in infant cognitive functioning. Research Highlights We used a hierarchical Bayesian model to measure individual differences in infants’ processing speed, learning performance, sustained attention, and curiosity. Faster processing speed was related to shorter habituation time. High curiosity was related to stronger dishabituation responses, but only for infants who did not habituate.

Background Daily skin‐to‐skin contact (SSC) during early infancy fosters the long‐term development of children born preterm. This is the first randomized controlled trial assessing the potential beneficial effects of daily SSC on executive functioning and socio‐emotional behavior of children born full‐term. Whether children of mothers who experienced prenatal stress and anxiety benefitted more from SSC was also explored. Methods Pregnant women ( N = 116) were randomly assigned to a SSC or care‐as‐usual (CAU) condition. Women in the SSC condition were instructed to perform one hour of SSC daily from birth until postnatal week five. Prenatal stress was measured with questionnaires on general and pregnancy‐specific stress and anxiety completed by the mothers in gestational week 37. At child age three, mothers filled in questionnaires on children's executive functioning, and externalizing and internalizing behavior. Analyses were performed in an intention‐to‐treat (ITT), per‐protocol, and dose–response approach. Netherlands Trial Register: NL5591 . Results In the ITT approach, fewer internalizing (95% CI = 0.11–1.00, U = 2148.50, r = .24, p = .001) and externalizing (95% CI = 0.04–2.62, t = 2.04, d = 0.38, p = .04) problems were reported in the SSC condition compared to the CAU condition. Multivariate analyses of variance did not show group differences on executive functioning. Additional analyses of covariance showed no moderations by maternal prenatal stress. Conclusions Current findings indicate that early daily SSC in full‐term infants may foster children's behavioral development. Future replications, including behavioral observations of child behavior to complement maternal reports, are warranted.