Figure 1.

Figure 1a (left): Mean number of unique words (types) as a function of number of total words (tokens) in child-directed speech and children’s picture books.

Figure 1b (right): Large black and gray points are the same type and token counts plotted in Figure 1a. Small black dots refer to the individual type and token counts of the 100 picture books and small gray dots refer to type and token counts of individual conversations in CHILDES.