Persistent difference in short-term memory span between sign and speech: implications for cross-linguistic comparisons.
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Humans↗
Biomedical subjects
Elissa L Newport
Publications and source records attributed to Elissa L Newport.
Grammatical Subjects in home sign: Abstract linguistic structure in adult primary gesture systems without linguistic input.
Language ordinarily emerges in young children as a consequence of both linguistic experience (for example, exposure to a spoken or signed language) and innate abilities (for example, the ability to acquire certain types of language patterns). One way to discern which aspects of language acquisition are controlled by experience and which arise from innate factors is to remove or manipulate linguistic input. However, experimental manipulations that involve depriving a child of language input are impossible. The present work examines the communication systems resulting from natural situations of language deprivation and thus explores the inherent tendency of humans to build communication systems of particular kinds, without any conventional linguistic input. We examined the gesture systems that three isolated deaf Nicaraguans (ages 14-23 years) have developed for use with their hearing families. These deaf individuals have had no contact with any conventional language, spoken or signed. To communicate with their families, they have each developed a gestural communication system within the home called "home sign." Our analysis focused on whether these systems show evidence of the grammatical category of Subject. Subjects are widely considered to be universal to human languages. Using specially designed elicitation tasks, we show that home signers also demonstrate the universal characteristics of Subjects in their gesture productions, despite the fact that their communicative systems have developed without exposure to a conventional language. These findings indicate that abstract linguistic structure, particularly the grammatical category of Subject, can emerge in the gestural modality without linguistic input.
Adolescent↗
Short-term memory span: insights from sign language.
Short-term memory (STM), or the ability to hold information in mind for a few seconds, is thought to be limited in its capacity to about 7 +/- 2 items. Notably, the average STM capacity when using American Sign Language (ASL) rather than English is only 5 +/- 1 items. Here we show that, contrary to previous interpretations, this difference cannot be attributed to phonological factors, item duration or reduced memory abilities in deaf people. We also show that, despite this difference in STM span, hearing speakers and deaf ASL users have comparable working memory resources during language use, indicating similar abilities to maintain and manipulate linguistic information. The shorter STM span in ASL users therefore confirms the view that the spoken span of 7 +/- 2 is an exception, probably owing to the reliance of speakers on auditory-based rather than visually based representations in linguistic STM, and calls for adjustments in the norms used with deaf individuals.
Adult↗
Learning at a distance II. Statistical learning of non-adjacent dependencies in a non-human primate.
In earlier work we have shown that adults, infants, and cotton-top tamarin monkeys are capable of computing the probability with which syllables occur in particular orders in rapidly presented streams of human speech, and of using these probabilities to group adjacent syllables into word-like units. We have also investigated adults' learning of regularities among elements that are not adjacent, and have found strong selectivities in their ability to learn various kinds of non-adjacent regularities. In the present paper we investigate the learning of these same non-adjacent regularities in tamarin monkeys, using the same materials and familiarization methods. Three types of languages were constructed. In one, words were formed by statistical regularities between non-adjacent syllables. Words contained predictable relations between syllables 1 and 3; syllable 2 varied. In a second type of language, words were formed by statistical regularities between non-adjacent segments. Words contained predictable relations between consonants; the vowels varied. In a third type of language, also formed by regularities between non-adjacent segments, words contained predictable relations between vowels; the consonants varied. Tamarin monkeys were exposed to these languages in the same fashion as adults (21 min of exposure to a continuous speech stream) and were then tested in a playback paradigm measuring spontaneous looking (no reinforcement). Adult subjects learned the second and third types of language easily, but failed to learn the first. However, tamarin monkeys showed a different pattern, learning the first and third type of languages but not the second. These differences held up over multiple replications, using different sounds instantiating each of the patterns. These results suggest differences among learners in the elementary units perceived in speech (syllables, consonants, and vowels) and/or the distance over which such units can be related, and therefore differences among learners in the types of patterned regularities they can acquire. Such studies with tamarins open interesting questions about the perceptual and computational capacities of human learners that may be essential for language acquisition, and how they may differ from those of non-human primates.
Animals↗
When learners surpass their models: the acquisition of American Sign Language from inconsistent input.
The present study examines the impact of highly inconsistent input on language acquisition. The American deaf community provides a unique opportunity to observe children exposed to nonnative language models as their only linguistic input. This research is a detailed case study of one child acquiring his native language in such circumstances. It asks whether this child is capable of organizing a natural language out of input data that are not representative of certain natural language principles. Simon is a deaf child whose deaf parents both learned American Sign Language (ASL) after age 15. Simon's only ASL input is provided by his late-learner parents. The study examines Simon's performance at age 7 on an ASL morphology task, compared with eight children who have native signing parents, and also compared with Simon's own parents. The results show that Simon's production of ASL substantially surpasses that of his parents. Simon's parents, like other late learners of ASL, perform below adult native signing criteria, with many inconsistencies and errors in their use of ASL morphology. In contrast, Simon's performance is much more regular, and in fact on most ASL morphemes is equal to that of children exposed to a native signing model. The results thus indicate that Simon is capable of acquiring a regular and orderly morphological rule system for which his input provides only highly inconsistent and noisy data. In addition, the results provide some insight into the mechanisms by which such learning may occur. Although the ASL situation is rare, it reveals clues that may contribute to our understanding of the human capacity for language learning.
Child↗
Learning at a distance I. Statistical learning of non-adjacent dependencies.
In earlier work we have shown that adults, young children, and infants are capable of computing transitional probabilities among adjacent syllables in rapidly presented streams of speech, and of using these statistics to group adjacent syllables into word-like units. In the present experiments we ask whether adult learners are also capable of such computations when the only available patterns occur in non-adjacent elements. In the first experiment, we present streams of speech in which precisely the same kinds of syllable regularities occur as in our previous studies, except that the patterned relations among syllables occur between non-adjacent syllables (with an intervening syllable that is unrelated). Under these circumstances we do not obtain our previous results: learners are quite poor at acquiring regular relations among non-adjacent syllables, even when the patterns are objectively quite simple. In subsequent experiments we show that learners are, in contrast, quite capable of acquiring patterned relations among non-adjacent segments-both non-adjacent consonants (with an intervening vocalic segment that is unrelated) and non-adjacent vowels (with an intervening consonantal segment that is unrelated). Finally, we discuss why human learners display these strong differences in learning differing types of non-adjacent regularities, and we conclude by suggesting that these contrasts in learnability may account for why human languages display non-adjacent regularities of one type much more widely than non-adjacent regularities of the other type.
Adult↗
Distant melodies: statistical learning of nonadjacent dependencies in tone sequences.
Human listeners can keep track of statistical regularities among temporally adjacent elements in both speech and musical streams. However, for speech streams, when statistical regularities occur among nonadjacent elements, only certain types of patterns are acquired. Here, using musical tone sequences, the authors investigate nonadjacent learning. When the elements were all similar in pitch range and timbre, learners acquired moderate regularities among adjacent tones but did not acquire highly consistent regularities among nonadjacent tones. However, when elements differed in pitch range or timbre, learners acquired statistical regularities among the similar, but temporally nonadjacent, elements. Finally, with a moderate grouping cue, both adjacent and nonadjacent statistics were learned, indicating that statistical learning is governed not only by temporal adjacency but also by Gestalt principles of similarity.
Auditory Perception↗
Segmenting nonsense: an event-related potential index of perceived onsets in continuous speech.
Speech segmentation, determining where one word ends and the next begins in continuous speech, is necessary for auditory language processing. However, because there are few direct indices of this fast, automatic process, it has been difficult to study. We recorded event-related brain potentials (ERPs) while adult humans listened to six pronounceable nonwords presented as continuous speech and compared the responses to nonword onsets before and after participants learned the nonsense words. In subjects showing the greatest behavioral evidence of word learning, word onsets elicited a larger N100 after than before training. Thus N100 amplitude indexes speech segmentation even for recently learned words without any acoustic segmentation cues. The timing and distribution of these results suggest specific processes that may be central to speech segmentation.
Acoustic Stimulation↗