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. Author manuscript; available in PMC: 2014 Jun 1.
Published in final edited form as: Dev Psychol. 2012 Jul 16;49(6):1027–1035. doi: 10.1037/a0029330

Figure 1.

Figure 1

Observed and predicted mean frequencies of A) Gazes at parent, B) Smiles, C) Positive social bids, and D) Cry-face expressions over time in the still-face episode. Frequencies refer to the number of frames per second (maximum 30) in which a particular behavior occurred. Social bids were defined as smiles in the presence of gazing at the parent. Predicted refers to the expected frequency based on a hierarchical linear model containing an intercept and a linear term indexing behavior change proportional to log10 transformation of the number of seconds elapsed. Although the model only contains linear terms, the log transformation allows for curvilinear change over seconds.