Effects of negative temperament on 5-month-old infants’ behavior during the still-face paradigm

• Infants’ temperament influences behaviors displayed during the still-face paradigm.
• Only high negative infants showed sustained negativity during the reunion phase.
• High and low negative infants did not differ in positivity or emotion regulation.
• Individual differences in temperament dramatically affect the carry-over effect.

Five-month-old infants characterized as low or high on temperamental negativity participated with their mothers in the still-face paradigm. Compared to low negative infants, high negative infants displayed greater negative engagement during reunion suggesting that infant temperament significantly contributes to individual differences in the still-face effect.