Table 1.
Demographics and recording ages.
Table 2.
Gestural illocutionary functions.
Table 3.
Vocal illocutionary functions.
Fig 1.
Proportion of events coded in the three global categories for the two individuals who independently coded 23 five-minute segments selected semi-randomly from 23 of the 36 recording sessions.
Fig 2.
Rate of communicative events per infant averaged across ages.
The box and whiskers plots represent all 4729 gestural and vocal events and are based on infant level calculations. Means are represented by an X in each box. In cases where outliers occurred, the upper whisker shows the highest value after outliers were removed from the distribution. All the raw individual data for the 12 infants are available in the data posted on-line.
Fig 3.
Mean rate per infant of Nonsocial acts.
These data are based on the 766 gestural and vocal events that were coded as Non-social across three ages. The entire range of the communicative events per min is represented in each box and whisker plot. Whiskers are not visible in cases where the lower quartile value is equal to the minimum value, which is reflected in the box and whisker plots for 16 months and 20 months in this figure. The means are represented by X’s in the boxes based on computation from the original data rather than from the modeled GEE values. The GEE analysis showed a statistically significant interaction of Age by Modality and a significant main effect of Modality, indicating higher rates of Non-social vocal than gestural events.
Fig 4.
Mean rate per infant of Universal acts.
The data are based on the 2140 gestural and vocal events that were coded as Universal communications across three ages. Again, the means of communicative events per min, represented by X’s in the boxes, are based on computation from the original data rather than from the GEE values, which indicated a significant interaction of Age by Modality, reflecting the rise in Universal gestures across Age contrasting with the fall in Universal vocalizations across Age.
Fig 5.
Mean rate per infant of Conventional acts.
The data are based on the 1823 gestural and vocal events that were coded as Conventional communications across three ages. Again, the means, represented by X’s, are based on computation from the original data on events per min rather than from the modeled GEE values, which indicated a significant interaction of Age by Modality, reflecting the rise in Conventional vocalizations across Age contrasting with no such rise in gestures across Age.
Fig 6.
Proportions of gaze directed gestural and vocal events.
The data are based on all coded gestural (1453) and vocal events (3253) where gaze direction could be judged based on at least one of the video signals. Again, the means reflect the raw data rather than the modeled GEE values.