Figure 3.

Mouth-looking to infant-directed song and speech as a function of age. Mouth-looking is quantified as the percentage of face-looking time spent on the mouth region (PFLT-m). Note this measure is the complementary percentage of eye-looking and can be reversed and read with respect to attention to eyes (i.e., 60% mouth-looking can also be interpreted as 40% eye-looking). The individual points show average mouth-looking time per child at each age point for song (orange circles) and speech (blue triangles), and the lines show the model predictions for each clip type (song: orange solid; speech: blue dashed). The shaded regions represent 95% confidence intervals around model predictions.