Robust patterns and individual variations: stability and predictors of infant behavior in the still-face paradigm.

In the present study we examined key issues regarding infant behavior in the still-face paradigm (SFP) in terms of individual variations, stability, and predictors. The sample consisted of 115 mothers and infants, with assessments at ages 3 and 6 months, including observations of maternal and infant behavior in the SFP, and parent reports of infant temperament. Both robust patterns and individual variations in infant SFP behaviors were found, with only a minority of infants showing the expected patterns for negative affect and gaze. Infant behavior patterns showed no stability from age 3 to 6 months, and infant gaze was related to more pronounced behavior changes across the SFP. Maternal sensitivity in the SFP baseline was related to some aspects of infant SFP behavior. Consistent with the differential susceptibility hypothesis, in infants with a more difficult temperament maternal sensitivity predicted a more pronounced expected pattern of changes in infant positive affect across the SFP, whereas this was not the case for infants with a more easy temperament.