Development of mother-infant interaction in tickling play: The relationship between infants' ticklishness and social behaviors

•Mother-infant tickling interactions were examined.•There were strong relationships between infants' ticklishness and social behaviors.•Mothers' narrative tickling was more frequent at 7 than at 5 months.•Narrative tickling may facilitate infants' active communication at a higher cognitive level.

This study examined the development of mother-infant tickling interaction and the relationship between infants' ticklishness and social behaviors including infants' looking at mothers' face, mothers' narrative tickling, and mothers' laughter. Twenty-two Japanese infants aged 5 months (n = 10, five girls) and 7 months (n = 12, four girls) and their mothers were videotaped. Results revealed that the mothers' narrative tickling was more frequent at 7 than at 5 months and the infants' strong ticklishness showed the same tendency. The infants' strong ticklishness was linked with the occurrence of other social behaviors. In conclusion, infants' ticklishness was heavily connected with social behaviors. The mode of the tickling interaction at 7 months was different from that at 5 months especially in the increase of mother's narrative tickling. A possible function of such mother's narrative tickling to facilitate infant active communication at a higher cognitive level including anticipation, was discussed.