Cognitive control factors in speech perception at 11 months

Abstract

The development of speech perception during the 1st year reflects increasing attunement to native language features, but the mechanisms underlying this development are not completely understood. One previous study linked reductions in nonnative speech discrimination to performance on nonlinguistic tasks, whereas other studies have shown associations between speech perception and vocabulary growth. The present study examined relationships among these abilities in 11-month-old infants using a conditioned head-turn test of native and nonnative speech sound discrimination, nonlinguistic object-retrieval tasks requiring attention and inhibitory control, and the MacArthur-Bates Communicative Development Inventory (L. Fenson et al., 1993). Native speech discrimination was positively linked to receptive vocabulary size but not to the cognitive control tasks, whereas nonnative speech discrimination was negatively linked to cognitive control scores but not to vocabulary size. Speech discrimination, vocabulary size, and cognitive control scores were not associated with more general cognitive measures. These results suggest specific relationships between domain-general inhibitory control processes and the ability to ignore variation in speech that is irrelevant to the native language and between the development of native language speech perception and vocabulary.

Figure 1

Stimuli used in Double-Target Head Turn task.

Figure 2

Spectrograms of stimuli used in Double-Target Head Turn task. Note. From “Brain potentials to native and non-native speech contrasts in 7- and 11-month-old American infants,” by M. Rivera-Gaxiola, J. Silva-Pereyra, and P. K. Kuhl, 2005, Developmental Science, 8(2), p. 165. Copyright 2005 by Blackwell Publishing, Ltd. Adapted with permission.

Figure 3

Double-Target Head Turn task procedure: On each conditioning trial the background sound changed to the target for 3 repetitions, and the mechanical toy was activated for 5s to allow the infant to learn the association between target sound and reinforcer. During the initial portion of each conditioning phase (native and nonnative), the target sound was presented with a 4 dB intensity cue. Following 2 consecutive correct head turns to the target, trials were administered without the intensity cue until 3 consecutive correct head turns were achieved. In the test phase, change and control (no sound change) trials occurred with equal probability (50%), and consecutive trials of one type were restricted to 3. Correct head turns on change trials were reinforced and recorded as “hits”, and incorrect head turns on control trials were recorded as “false alarms”.

Figure 4

Discrimination performance on the native and nonnative speech contrasts, by MacArthur-Bates CDI receptive vocabulary scores.

Figure 5

Discrimination performance on the native and nonnative speech contrasts, by Means-end scores.

Figure 6

Discrimination performance on the native and nonnative speech contrasts, by Detour-reaching scores.