Perceptual Learning and Production Practice Differentially Affect How Children Produce Novel Words.

Purpose Perceptual learning and production practice are basic mechanisms that children depend on to acquire adult levels of speech accuracy. In this study, we examined perceptual learning and production practice as they contributed to changes in speech accuracy in 3- and 4-year-old children. Our primary focus was manipulating the order of perceptual learning and production practice to better understand when and how these learning mechanisms interact. Method Sixty-five typically developing children between the ages of 3 and 4 years were included in the study. Children were asked to produce CVCCVC (C = consonant, V = vowel) nonwords like /bozjəm/ and /tʌvtʃəp/ that were described as the names of make-believe animals. All children completed two separate experimental blocks: a control block in which participants heard each nonword once and repeated it, and a test block in which the perceptual input frequency of each nonword varied between 1 and 10. Half of the participants completed a control-test order; half completed a test-control order. Results Greater accuracy was observed for nonwords produced in the second experimental block, reflecting a production practice effect. Perceptual learning resulted in greater accuracy during the test for nonwords that participants heard 3 times or more. However, perceptual learning did not carry over to control productions in the test-control design, suggesting that it reflects a kind of temporary priming. Finally, a post hoc analysis suggested that the size of the production practice effect depended on the age of acquisition of the consonants that comprised the nonwords. Conclusions The study provides new details about how perceptual learning and production practice interact with each other and with phonological aspects of the nonwords, resulting in complex effects on speech accuracy and learning of form-referent pairs. These findings may ultimately help speech-language pathologists maximize their clients' improvement in therapy. Supplemental Material https://doi.org/10.23641/asha.12971411.

Frequencies in Perception and Production Differentially Affect Child Speech.

Purpose: Frequent sounds and frequent words are both acquired at an earlier age and are produced by children more accurately. Recent research suggests that frequency is not always a facilitative concept, however. Interactions between input frequency in perception and practice frequency in production may limit or inhibit growth. In this study, we consider how a range of input frequencies affect production accuracy and referent identification. Method: Thirty-three typically developing 3- and 4-year-olds participated in a novel word-learning task. In the initial test block, participants heard nonwords 1, 3, 6, or 10 times-produced either by a single talker or by multiple talkers-and then produced them immediately. In a posttest, participants heard all nonwords just once and then produced them. Referent identification was probed in between the test and posttest. Results: Production accuracy was most clearly facilitated by an input frequency of 3 during the test block. Input frequency interacted with production practice, and the facilitative effect of input frequency did not carry over to the posttest. Talker variability did not affect accuracy, regardless of input frequency. The referent identification results did not favor talker variability or a particular input frequency value, but participants were able to learn the words at better than chance levels. Conclusions: The results confirm that the input can be facilitative, but input frequency and production practice interact in ways that limit input-based learning, and more input is not always better. Future research on this interaction may allow clinicians to optimize various types of frequency commonly used during therapy.

Perceptual statistical learning over one week in child speech production.

What cognitive mechanisms account for the trajectory of speech sound development, in particular, gradually increasing accuracy during childhood? An intriguing potential contributor is statistical learning, a type of learning that has been studied frequently in infant perception but less often in child speech production. To assess the relevance of statistical learning to developing speech accuracy, we carried out a statistical learning experiment with four- and five-year-olds in which statistical learning was examined over one week. Children were familiarized with and tested on word-medial consonant sequences in novel words. There was only modest evidence for statistical learning, primarily in the first few productions of the first session. This initial learning effect nevertheless aligns with previous statistical learning research. Furthermore, the overall learning effect was similar to an estimate of weekly accuracy growth based on normative studies. The results implicate other important factors in speech sound development, particularly learning via production.

Learning trajectories for speech motor performance in children with specific language impairment.

UNLABELLED: Children with specific language impairment (SLI) often perform below expected levels, including on tests of motor skill and in learning tasks, particularly procedural learning. In this experiment we examined the possibility that children with SLI might also have a motor learning deficit. Twelve children with SLI and thirteen children with typical development (TD) produced complex nonwords in an imitation task. Productions were collected across three blocks, with the first and second blocks on the same day and the third block one week later. Children's lip movements while producing the nonwords were recorded using an Optotrak camera system. Movements were then analyzed for production duration and stability. Movement analyses indicated that both groups of children produced shorter productions in later blocks (corroborated by an acoustic analysis), and the rate of change was comparable for the TD and SLI groups. A nonsignificant trend for more stable productions was also observed in both groups. SLI is regularly accompanied by a motor deficit, and this study does not dispute that. However, children with SLI learned to make more efficient productions at a rate similar to their peers with TD, revealing some modification of the motor deficit associated with SLI. LEARNING OUTCOMES: The reader will learn about deficits commonly associated with specific language impairment (SLI) that often occur alongside the hallmark language deficit. The authors present an experiment showing that children with SLI improved speech motor performance at a similar rate compared to typically developing children. The implication is that speech motor learning is not impaired in children with SLI.

Word-types, not word-tokens, facilitate extraction of phonotactic sequences by adults.

Phonotactics-the permissibility of sound sequences within a word-correspond to lexical statistics, but controversy persists over which statistics are being tracked. In this study, lexical type and token counts were compared as they contributed to phonotactic extraction from an artificial lexicon. Young-adult participants were familiarized with a set of CVCCVC nonwords contextualized as a lexicon of Martian animal names. The type and token frequencies of word-medial consonant sequences within those names were varied systematically. Participants then rated new nonwords, containing the same medial sequences, on a 7-point scale for similarity to the Martian animal names. Higher ratings only followed high type frequency familiarization conditions, suggesting that word-types drove phonotactic extraction. Additionally, participants reversed the typical preference for high frequency English sequences, likely because they rated nonwords according to their membership to an unknown language. This finding suggests cognitively separable tracking of artificial language statistics and preexisting representations.

Statistical frequency in perception affects children's lexical production.

Children's early word production is influenced by the statistical frequency of speech sounds and combinations. Three experiments asked whether this production effect can be explained by a perceptual learning mechanism that is sensitive to word-token frequency and/or variability. Four-year-olds were exposed to nonwords that were either frequent (presented 10 times) or infrequent (presented once). When the frequent nonwords were spoken by the same talker, children showed no significant effect of perceptual frequency on production. When the frequent nonwords were spoken by different talkers, children produced them with fewer errors and shorter latencies. The results implicate token variability in perceptual learning.