LAUSR

Abstract We compare matching of facial expressions of emotion, completion of the positive valence of emotional expression, attunement of emotional intensity, and non-matching of emotion, in engagements with their mothers of firstborn dizygotic twins and of singletons. Nine twins and nine singletons were video-recorded at home in spontaneous face-to-face interactions from the second to the sixth month after birth. Microanalysis of infant and maternal facial expressions of emotion revealed qualitative and quantitative differences that indicate that engagements with twins had more frequent and more accurate emotional matching and attunements compared to those with singletons. Singletons displayed more emotional completion and non-matching reactions. Expressions of matching for pleasure and interest followed different developmental patterns in the two kinds of dyads. These results are discussed in relation to the theory of innate affective intersubjectivity. Differences may shed light on the relationship between sharing early life with a twin, and development of self-other awareness.