Given are the line graphs that compare the number of spoken words and vocabulary size that child aged 1-4 and 1-3 years accumulated in three different family's categories.
It is clear from the provided information that there is a positive correlation between the stored words, the capacity to talk, and family's talkativeness in child's language development.
In detail, although all figures was rising in all given period, it seems like the surrounding matters most in child's language acquisition. When the toddler were 3 years old, for example, the lowest-talking family's child on average has 400 words compared to 1000 words of higher-talking families. In total spoken words, the gap was increasingly higher; the average gap of all points were approximately 2 million words, then it became virtually 15 million words when child was 4 years old.
Another striking feature is that child spoke more than vocabularies that he already acquired at any given figure.