The importance of rapid auditory processing abilities to early language development: evidence from converging methodologies

Abstract

The ability to process two or more rapidly presented, successive, auditory stimuli is believed to underlie successful language acquisition. Likewise, deficits in rapid auditory processing of both verbal and nonverbal stimuli are characteristic of individuals with developmental language disorders such as Specific Language Impairment. Auditory processing abilities are well developed in infancy, and thus such deficits should be detectable in infants. In the studies presented here, converging methodologies are used to examine such abilities in infants with and without a family history of language disorder. Behavioral measures, including assessments of infant information processing, and an EEG/event-related potential (ERP) paradigm are used concurrently. Results suggest that rapid auditory processing skills differ as a function of family history and are predictive of later language outcome. Further, these paradigms may prove to be sensitive tools for identifying children with poor processing skills in infancy and thus at a higher risk for developing a language disorder.

FIGURE 1

Trial-by-trial recording for the test phase of the RAP go/no go task from a 28-week-old infant with a family history of language-based learning disability. At 500-ms ISI, this infant had no difficulty discriminating one tone sequence from another, but once the ISI dropped below 250 ms, discrimination dropped to chance levels. The RAP threshold is 262 ms.

FIGURE 2

Discrimination of consonant vowel syllables (/ba/ vs /da/) as compared to face discrimination in infants with a family history of SLI and matched controls (n = 44).

FIGURE 3

Association between latency to hits and slope of habituation function for 70-ms ISI at 6 months.

FIGURE 4

Photograph of a 6-month-old child seated on his mother’s lap during an ERP testing session.

FIGURE 5

Panel A: Brain electrical responses (averaged across participants) for tone pairs with the within-pair intervals of 70 and 300 ms in adults (n = 12) and 24-month-old infants (n = 9). The stimuli presentations are represented by two gray boxes. Panel B: Scalp surface maps of the standard and deviant responses at the time point of the peaks indicated by the blue arrows in Panel A. The red circles on the surface maps indicate the electrode site from which the ERPs displayed in Panel A are taken. Note the different scaling of the potential maps for the ERPs of adults and infants.