“(i) Smiling can be used as a pre-laughing device: laughing together can be entered step-wise, and smiling is a common device for paving the way to the laughter. (ii) Smiling can be used as a response to laughter in the previous turn.”
These smile-functions were revealed during an experimental study which used data from Finnish primary healthcare interactions and convenience store encounters. Dr. Haakana’s research goes on to show that :
“… smiling as a response to laughter can have several interactional functions. It can be used to acknowledge the laughability of the previous turn, and sometimes even provides strong uptake of its laughability. However, smiling can also be an affiliative response to prior utterances that are constructed as delicate and troublesome (by laughter and other means). Laughter and smiling have different functions in different sequential and verbal contexts.”
See: Laughter and smiling: Notes on co-occurrences in the Journal of Pragmatics Volume 42, Issue 6, June 2010, Pages 1499-1512.