Penn study finds quality trumps quantity in language acquisition

The more parents speak to their children, the bigger their vocabularies are when they begin school. Research has indicated that richer parents speak to their children more often than poorer parents do, deepening the educational disadvantage facing many children living in poverty.

A new study led by Penn's John Trueswell and Lila Gleitman, professors of psychology in the School of Arts & Sciences, reports that this situation may not be as troublesome as it seems. The psychologists found that the way parents speak to their children matters more than the sheer quantity of the words they say.

“We see that the more an environment maximizes the ‘here-and-nowness’ of speech, such as when a parent is gesturing or looking at the object in question, the more likely it is that an interaction will be highly informative,” Gleitman says.

Trueswell, Gleitman, and their colleagues have long hypothesized that children learn their first words in “eureka” moments—that is, only after such highly informative examples. Their efforts to investigate this mechanism began several years ago, when the researchers visited more than 50 families from various backgrounds in their homes and videotaped parents interacting with their children.

To estimate the rates at which the children were receiving highly informative examples from their parents, the researchers simulated the experience for a large panel of adult volunteers.

Gleitman and Trueswell made a number of 40-second segments from the taped interactions, each centered on one instance of a parent saying a common, concrete noun, such as “book,” “ball,” or “dog.” They showed these segments to the volunteers but muted the video until the parent reached the target word, which was replaced by a beep. If more than half the volunteers could guess the word correctly, the example was deemed to be highly informative.

The researchers found a surprising amount of variability between families. Parents who provided highly informative examples at the highest rate did so 38 percent of the time, while those who provided the lowest rate did so only 4 percent of the time. The effect of this discrepancy was clear when the researchers tracked how well each of the children did on a standard vocabulary test three years later: The more frequently a child heard highly informative examples of speech, the better he or she did on these tests.

But critically, the rate at which a parent gave highly informative examples to their children wasn’t correlated to the amount they spoke in total. Trueswell says this is potentially hopeful news, given the studies that link low socioeconomic status (SES) to low speech quantity, and thus to poor scholastic performance.   

“There are a variety of reasons why low-SES parents are speaking less to their children,” he says, “but, when they do speak to them, their natural predispositions about talking about the ‘here and now’ don’t seem to be correlated to their SES.”