Figure 2. Eye constriction (the Duchenne marker) is differentially associated with smiles and cry-faces in the Face-to-Face/Still-Face (FFSF).

Mean proportions of smiles and of cry-faces occurring with eye constriction. Error bars indicate standard errors of the mean. The images are of smiles and cry-faces with eye constriction. The images are from a six-month-old in the FFSF in the current study. Written informed consent, as outlined in the PLOS consent form, was obtained for publication of these images.