Learning words and learning sounds: Advances in language development

Reverse production effect: children recognize novel words better when they are heard rather than produced

This research investigates the effect of production on 4.5- to 6-year-old children's recognition of newly learned words. In Experiment 1, children were taught four novel words in a produced or heard training condition during a brief training phase. In Experiment 2, children were taught eight novel words, and this time training condition was in a blocked design. Immediately after training, children were tested on their recognition of the trained novel words using a preferential looking paradigm. In both experiments, children recognized novel words that were produced and heard during training, but demonstrated better recognition for items that were heard. These findings are opposite to previous results reported in the literature with adults and children. Our results show that benefits of speech production for word learning are dependent on factors such as task complexity and the developmental stage of the learner.

Early phonology revealed by international adoptees' birth language retention

Until at least 6 mo of age, infants show good discrimination for familiar phonetic contrasts (i.e., those heard in the environmental language) and contrasts that are unfamiliar. Adult-like discrimination (significantly worse for nonnative than for native contrasts) appears only later, by 9-10 mo. This has been interpreted as indicating that infants have no knowledge of phonology until vocabulary development begins, after 6 mo of age. Recently, however, word recognition has been observed before age 6 mo, apparently decoupling the vocabulary and phonology acquisition processes. Here we show that phonological acquisition is also in progress before 6 mo of age. The evidence comes from retention of birth-language knowledge in international adoptees. In the largest ever such study, we recruited 29 adult Dutch speakers who had been adopted from Korea when young and had no conscious knowledge of Korean language at all. Half were adopted at age 3-5 mo (before native-specific discrimination develops) and half at 17 mo or older (after word learning has begun). In a short intensive training program, we observe that adoptees (compared with 29 matched controls) more rapidly learn tripartite Korean consonant distinctions without counterparts in their later-acquired Dutch, suggesting that the adoptees retained phonological knowledge about the Korean distinction. The advantage is equivalent for the younger-adopted and the older-adopted groups, and both groups not only acquire the tripartite distinction for the trained consonants but also generalize it to untrained consonants. Although infants younger than 6 mo can still discriminate unfamiliar phonetic distinctions, this finding indicates that native-language phonological knowledge is nonetheless being acquired at that age.

The infant's developmental path in phonological acquisition

Research on how language acquisition begins has been fragmented both in terms of scientific communities and in terms of the phenomena that are taken to characterize developmental progress. In her article, Marilyn Vihman argues for an integrative approach that takes the child's efforts at speech production as primary, and notes that infants' knowledge of how words sound may accrue over a protracted period developmentally. Here, I briefly discuss how reconceptualization of the process can help integrate perspectives previously at odds.

In search of a learning model

While the four commentaries reflect a range of different perspectives on my target paper (Vihman, 2017), all basically accept the overall approach, which has been central to my research for 30 years. Each commentary proposes ways of deepening aspects of the ideas expressed or points out limitations and potential areas in which elaboration would be useful. This response takes up each commentary in turn.

Sound categories or phonemes?

Vihman emphasizes the importance of early word production to the emergence of phonological knowledge. This emphasis, consistent with the generative function of phonology, provides insight into the concurrent representation of phonemes and words. At the same time, Vihman's focus on phonology leads her to possibly overstate the influence of early word acquisition on the emergence of sound categories that are probably purely phonetic in nature at the outset of learning.