SES differences in language processing skill and vocabulary are evident at 18 months

Abstract

This research revealed both similarities and striking differences in early language proficiency among infants from a broad range of advantaged and disadvantaged families. English-learning infants (n = 48) were followed longitudinally from 18 to 24 months, using real-time measures of spoken language processing. The first goal was to track developmental changes in processing efficiency in relation to vocabulary learning in this diverse sample. The second goal was to examine differences in these crucial aspects of early language development in relation to family socioeconomic status (SES). The most important findings were that significant disparities in vocabulary and language processing efficiency were already evident at 18 months between infants from higher- and lower-SES families, and by 24 months there was a 6-month gap between SES groups in processing skills critical to language development.

© 2012 Blackwell Publishing Ltd.

Figures

Figure 1

Scatter plots of Vocabulary, Accuracy and RT at 18 months with SES (HI). Dashed vertical line indicates median split of HI values.

Figure 2

Mean number of spoken words reported on the MacArthur/Bates CDI by age and SES (HI). Error bars represent SE of the mean over participants.

Figure 3

Mean proportion looking to the target picture as a function of time in ms from noun onset at 18 and 24 months. Error bars represent SE of the mean over participants. The vertical dashed line marks the acoustic offset of the target word.

Figure 4

Mean proportion of looking to the target as a function of time in ms from noun onset for Lower-SES and Higher-SES learners. Open squares/circles represent the time course of correct looking at 18 months; filled squares/circles represent the time course of looking in the same children at 24 months. Error bars represent SE of the mean over participants.

Figure 5

Mean RT to initiate a shift from the distracter to the target picture at 18 and 24 months for the Higher-SES and Lower-SES learners. Error bars represent SE of the mean over participants.