Do poor children hear 30 million fewer words by age 3?

Question

According to PolitiFact.com, Barack Obama stated that:

By the time she turns 3 years old, a child born into a low-income home hears 30 million fewer words than a child from a well-off family.

Furthermore, PolitiFact.com reported here that this claim is true, on the basis of the research of child psychologists Betty Hart and Todd Risley published in the book Meaningful Differences in the Everyday Experience of Young American Children. There's even an advocacy group called the Thirty Million Words Initiative directed by professor Dana Suskind at the University of Chicago.

The problem is that this number seems implausible to me, since 30,000,000 is roughly 1 word/second for 8 hours a day every day for 3 years.

Is this claim actually true?

Edit: The original paper behind the research, "The Early Catastrophe" by Hart and Risley, is available freely from Harvard here.

Answer 1

The article from which this claim stems has multiple issues. The most glaring is that even though its subtitle is "The 30 Million Word Gap by Age 3", the body of the article never actually makes this claim, instead claiming that there is a 32 million gap by age 4.

The authors of the article gathered data on how many words per hour a child heard through monthly 1-hour observations starting at 7-9 months of age and ending at 33-36 months of age. How and when this observation was conducted is not described. On average during this observation, children in families on welfare heard an average of 616 words while children from professional families heard an average of 2153 words. They assume that children are exposed to the same number of words per hour for 14 hours/day, and conclude that:

In four years of such experience, an average child in a professional family would have accumulated experience with almost 45 million words, an average child in a working-class family would have accumulated experience with 26 million words, and an average child in a welfare family would have accumulated experience with 13 million words.

This of course doesn't match the claim in the subtitle (since it refers to age 4). A couple of severe problems in the analysis stand out:

• The assumption that children are exposed to the same number of words for 14 hours per day as in the one hour of observation is suspect, and is impossible to evaluate since the conditions of observation are not described.

• Presumably people talk less to babies than to children who can understand them, so extrapolating the constant rate of exposure back to birth is unreasonable.

The math is also a little off: 2153 words/hour for 14 hours a day for 4 years works out to 44.01 million, not 45 million. Based on their numbers and assumptions, the actual word gap by age 3 is 23.6 million words.

The article also seems to have never been subject to peer review, appearing first in a book by the authors and later being reprinted in the magazine "American Educator", published by the American Federation of Teachers. Google Scholar lists the correct citation as

Hart, Betty, and Todd R. Risley. "The early catastrophe." Education Review 17.1 (2003).

However, the only journals I was able to find with that name are a journal of book reviews and what appears to be a magazine, neither of which published it.

On the whole, it seems that the word gap is large, but the claim probably significantly exaggerates it.