Observed weekly 13 infants from 1 to 6 months of age to determine when they produced different types of smiling and other facial expressions. Found that the cheek-raise and open-mouth dimensions of smiling appear to be associated with, respectively, amplification of processes of sharing positive affect and of visual engagement present to a lesser…

Compared Duchenne and non-Duchenne smiles of 1- to 6-month olds during weekly videotapes of mother/infant interaction for clues regarding emotional significance. Correlated levels of Duchenne and non-Duchenne smiling within sessions; found that they had similar developmental trajectories. Duchenne smiles were typically preceded by non-Duchenne…