The appearance of ‘filler syllables’ (called here PAEs, for Prefixed Additional Elements) in the late single-word period is analysed in relation to the emergence of grammatical morphemes, by confronting data from the longitudinal study of one child acquiring French, video- recorded between 1;3.2 and 2;2.6, with four hypotheses making different claims about the kind of language knowledge underlying their production: the DEVICES TO LENGTHEN SINGLE-WORD UTTERANCES, the SYNTACTIC SLOTS, the SELECTIVITY OF OCCURRENCE, and the ORGANIZATION OF SURFACE REGULARITIES hypotheses. The pattern of results concerning the first two to three months' production of PAEs points to the existence of a premorphological period in which PAEs result from the organization of phonoprosodic regularities of the language rather than being constrained by structural rules relative to syntactic slots or to the class of the word they precede. This premorphological period is followed by a protomorphological one in which incipient properties of grammatical morphemes and of word classes start to appear at the same time.

This study examines pragmatic factors that bias English-speaking children to produce more of the nouns and fewer of the verbs that they know. If nouns are favoured for production, parents should elicit more nouns than verbs in child speech. If verb comprehension is favoured over verb production, parents should more often prompt children to produce an action than to produce a verb. Data from 44 parent–child (age 1;8) dyads in the New England directory of the CHILDES data base were analysed. Children produced more nouns than verbs but mothers produced more verbs than nouns. Speech act analyses indicate that mothers elicited noun production but rarely prompted children to produce verbs. Mothers more often prompted children to produce an action than to produce a verb, and verbs occurred most often in maternal speech acts used to elicit children's actions. Moreover, children comprehended many more verbs than they produced. These data suggest that production measures underestimate the frequency and significance of verb-learning in early lexical development.

Early acquisition of nouns and verbs across languages is a key issue for a number of recent studies that question the reality of the ‘noun-bias’ and wonder about the reasons why it exists as they explore the role of cognitive vs. more language-specific input factors. Addressing this issue, the present study investigates how the noun and verb word classes develop in the free speech of a French child between the ages of 1;2 and 2;6, from the perspective of semantic and grammatical development. The analyses indicate that, in French acquisition, nouns clearly predominate over verbs until age 1;8 at least, but that verbs are produced in the early stages. Concrete object names among nouns and concrete action verbs among verbs were found to be the most prevalent categories, but they were not the earliest to appear and their distribution revealed an asymmetry in the conceptual packaging of nouns and verbs. Verb grammaticalization, assessed through inflection and auxiliary use, lagged somewhat behind noun grammaticalization, assessed through determiner use. This result supports the hypothesized noun–verb grammatical asynchrony. Verb grammaticalization seems to be related to the production of concrete action verbs, and noun grammaticalization to that of concrete object nouns, indicating interactions between semantic and grammatical development. These findings, discussed in a cross-linguistic perspective, suggest that both conceptual and grammatical packaging are important and interacting factors in noun and verb development, and argue in favour of a constructivist approach to language acquisition.

Previous research has focused on evaluating the nouns and verbs in parents' input through type/token ratios. This research offers an additional means of evaluating parent speech by first examining the frequencies of individual nouns, verbs and descriptors and second examining the learning task presented to children. Study 1 examines 25 transcripts from the CHILDES database of English-speaking parents' speech to children at five developmental levels ranging from 0;11 to 2;11 in age. Study 2 examines 50 transcripts from the CHILDES database of Mandarin-speaking caregivers' speech to children ranging from 1;9 to 2;3 in age. The results suggest that the patterns of frequency for individual nouns and individual verbs are different, but that the frequency patterns for nouns and the frequency patterns for verbs are similar in English and Mandarin. Further, this research suggests that in both languages the nouns in parents' input are similarly organized: the most frequent nouns spoken to children tend to name solid objects that share a similar shape. In contrast verbs' meanings in both languages tend to include more variable conceptual relations.

This paper reports the findings of a cross-sectional study that investigated the acquisition of relative clauses by 27 Tamil-speaking children, who ranged in age from 2;11 to 6;6. A picture-cued production task was used to elicit relative clauses from the child subjects. An analysis of the subjects' responses revealed that children below the age of 5;0 relativized significantly less often than the older children; furthermore, when they did produce relative clauses, they exhibited a strong preference for the tag relative and produced significantly fewer participial relatives than the older children. The findings also indicated that the younger children produced a significantly greater number of pragmatically inappropriate responses than the older children. It is argued that the observed age-related differences in Tamil children's relativizations very likely stem from performance factors and that the younger children are probably not inferior to the older children with respect to their grammatical and pragmatic competence.

The relation of lexical and grammatical knowledge is at the core of many controversies in linguistics and psycholinguistics. Recent empirical findings that the two are highly correlated in early language development have further energized the theoretical debate. Behavioural genetics provides an illuminating new tool to explore this question, by addressing the question of whether the empirical correlation simply reflects the fact that environments which facilitate one aspect of language growth also facilitate the other, or whether the same underlying acquisition mechanisms, influenced by the same genes, are responsible for the correlation. We explored this issue in a study of 2898 pairs of two-year-old twins born in England and Wales. Language development was assessed by their parents using an adapted version of the MacArthur Communicative Development Inventory which assesses vocabulary and grammar. Moderate heritabilities were found for both. As in previous studies, measures of vocabulary and sentence complexity were substantially correlated (r = 0·66). Behaviour-genetic modelling of the relation of vocabulary and grammar produced an estimated value of 0·61 for the genetic correlation, a measure of the overlap of the genetic effects that contribute to the two aspects of language development. In contrast, a measure of nonverbal cognitive development, the PARCA, was only weakly correlated at both the phenotypic level and at the level of genetic correlations with the language measures. Thus, although the distinction between verbal and nonverbal skills has a genetic basis underlying the phenotypic dissociation, there is little evidence either genetically or phenotypically for a dissociation between vocabulary and grammar within language.

Expressive language outcomes measured by MLU and the Index of Productive Syntax (IPSyn) at ages 3;0 and 4;0 were investigated in 34 late talkers with normal receptive language identified between 2;0 to 2;7 and 16 typically developing comparison children matched on age, SES, and nonverbal ability. Late talkers made greater gains than comparison children between 3;0 and 4;0 in both MLU and IPSyn raw score. However, when age-standardized z-scores were analysed, the late talkers were about 2·5 standard deviations below comparison children on both measures at both ages. At 3;0, 41% of the late talkers had MLUs above the 10th percentile based on Scarborough's (1990) benchmark sample; by 4;0, 71% did so. Using the IPSyn, a more stringent measure, 34% scored above the 10th percentile at 3;0 and only 29% did so at 4;0. MLU was significantly correlated with the IPSyn at both ages for the late talkers, but only at 3;0 for the comparison children. A converging set of regression analyses indicated no group differences in the predictive relationship between MLU and IPSyn, suggesting that the late talkers were delayed on both measures but not deviant in their development.

This study set out to explore the contexts in which preschool children use private speech, or self-talk, in the naturalistic setting of the preschool classroom, and age-related changes in the contexts in which preschoolers talk to themselves. A total of 2752 naturalistic observations of fourteen three-year-old and fourteen four-year-old children were conducted using a time-sampling procedure in two preschool classrooms over the course of one semester. Results from logistic regression analyses revealed that both age groups were (a) more likely to use private speech during the self-selected activity classroom context as opposed to both large group and outside free play classroom contexts, and (b) most likely to talk to themselves when alone, next likely in the presence of peers, and least likely when in the presence of a teacher. Although the probability of private speech among three-year-old children did not vary as a function of the child's immediate activity, four-year-old children's private speech was more likely to occur during sustained and focused goal-directed activity as opposed to rapidly-changing and non goal-directed activity. The findings suggest that private speech appears systematically in young children and that, in several ways, four-year-old children use private speech more selectively than three-year-olds.

Communicative Development Inventories (CDIs) were collected from 669 British children aged between 1;0 and 2;1. Comprehension and production scores in each age group are calculated. This provides norming data for the British infant population. The influence of socio-economic group on vocabulary scores is considered and shown not to have a significant effect. The data from British infants is compared to data from American infants (Fenson, Dale, Reznick, Bates, Thal & Pethick, 1994). It is found that British infants have lower scores on both comprehension and production than American infants of the same age.

In my paper Patterns of Pronoun Case Error (Rispoli, 1998b), I documented two aspects of pronoun case errors arising out of principles of lexical retrieval that are operative during the acquisition of the word specific pronoun case paradigms of English. The two aspects were; (a) the ‘double-cell effect,’ a supercharging of the her for she error rate; and (b) the ‘antagonism’ between the stereotypic objective for nominative replacement (e.g. him for he) and the rarer nominative overextensions (e.g. he for him/his). In my response, I shall address Schütze's criticisms in both of these areas. The response begins by addressing issues surrounding the double-cell effect. It then moves to issues surrounding antagonism.

Review essay on: B. MACWHINNEY (ed.), The emergence of language. Mahwah, NJ: Erlbaum, 1999.

An old joke that has been circulating for the past decade or so goes as follows: a biologist, a physicist, and a cognitive scientist were sitting around discussing the great achievements of their fields. The biologist waxed eloquent about the insights of Darwin's theory of evolution; the physicist expounded on the implications of Einstein's theory of general relativity. Then the cognitive scientist spoke up: ‘Our great discovery is the thermos. You put a cold drink in, the drink stays cold. You fill it with hot soup, the soup stays hot. This is amazing, for how does the thermos know?’

Obviously, this cognitive scientist has asked the wrong question about how the thermos maintains temperatures. In The emergence of language (henceforth, EL), an edited collection of chapters authored by an interdisciplinary group of computer scientists, linguists, and cognitive and developmental psychologists, it is suggested that perhaps language acquisition researchers have been making the same mistake as the errant cognitive scientist. To be sure, language is an extremely complex phenomenon, yet it is also elegant. Recognition of these characteristics in all aspects of language (thanks in large part to Chomskyan approaches to linguistics) highlights a well-known apparent paradox: language is hopelessly complex but children acquire it with ease. Solutions to this paradox have typically inspired researchers to posit rules or other kinds of blueprints – knowledge (innate or acquired) that children have to guide their language acquisition. But are these rules truly necessary? Perhaps children do not KNOW how to acquire language any more than a thermos knows how to maintain temperature.

Sabbagh & Gelman (S&G) present an insightful criticism of the emergentist approach to language acquisition. The analysis takes as its starting point an expressed frustration with the fact that emergentism is not packaged as a single theory or formalism. As a result, S&G decide to focus their critical attention on a particularly strong version of emergentism in which, ‘only domain-general tools are required to account for language development.’ This strong formulation of the emergentist position matches up well with the disembodied connectionism of the 1980s (Rumelhart & McClelland, 1986). However, it misrepresents the richer expressions of emergentism being developed by the authors of this volume. In particular, this ‘strong’ version fails to properly appreciate the degree to which emergentists view cognition as grounded on the body, the brain, and the social situation.

Consider a simple example from phonological development. There is a universal tendency to avoid sequences of nasal consonants followed by voiceless obstruents, as might arise in forms like ‘manpower.’ This constraint is grounded on the facts of speech production (Huffman, 1993) and figures prominently in recent elaborations of Optimality Theory (Kager, 1999). Languages use at least five phonological processes to deal with this problem. These processes include nasal substitution, post-nasal voicing, denasalization, nasal deletion, and vowel epenthesis. Initially, children may apply a variety of these processes (Bernhardt & Stemberger, 1998). Which processes are preserved and which are dropped out will depend on the shape of the target language, whether it be Indonesian, Quechua, Toba Batak, English, or Kelantan Malay. In the terms used by S&G, each of these phonological processes is a small emergentist ‘buzzsaw’ cutting patterns that are shaped not by some innate cognitive ‘blueprint,’ but by the emergent facts of articulatory phonology.

The review article by Sabbagh & Gelman (S & G) on The emergence of language (EL) mentions several criticisms of strong emergentism, the view that language emerges through an interaction between domain-general learning mechanisms and the environment, without crediting the organism with innate knowledge of domain-specific rules, a view that successful connectionist modelling is taken to support. One criticism of this view and the support for it that connectionist modelling putatively provides has been made frequently, and is noted by S & G: it is arguable that connectionist simulations work only because the input to the network in effect contains a representation of the knowledge that the net seeks to acquire. I think it is worth adding to this another criticism that to my mind is a fundamental one, but which has not featured so strongly in critiques of connectionism. A primary goal of modern linguistics has been to account not merely for what patterns we do see in human languages, but for those that we do not. The concept of Universal Grammar is precisely a set of limitations on what constitutes a possible human language. The kind of example used in teaching Linguistics 101 is the fact that patterns of grammaticality are structurally, not linearly, determined: in English we form a yes–no question by inverting the subject NP and auxiliary verb, not by inverting the first and second words of the equivalent declarative sentence, or the first and fifth words, or any number of conceivable non-structural operations. Could a connectionist mechanism learn such non-structural operations? Perhaps I have asked the wrong people, but when I have queried researchers doing connectionist modelling, the answer appears to be ‘yes’. If that's the case, then connectionist mechanisms as currently developed do not constitute an explanatory model of human language abilities: they are too powerful.

In The emergence of language, it is argued that much of what generative linguistics has characterized as ‘rules’ in fact can be derived from domain- general cognitive mechanisms. One example of this perspective is Bates & Goodman's contribution ‘On the emergence of grammar in the lexicon’, which Sabbagh & Gelman say offers ‘…a series of compelling arguments detailing how development and early acquisition shape the subsequent acquisition of new information.’ The thrust of the argument presented by Bates & Goodman is that there is no need to posit the existence of an independent grammar domain, because grammar can be reduced to the lexicon, which in Bates & Goodman's account, can be acquired using general purpose mechanisms. One of several major arguments in favour of this position presented by the authors is that grammar and vocabulary grow at the same rates in child speech. Thus, the authors argue that the development of the lexicon and grammar correlate because there is no grammar outside of the lexicon.

Since Noam Chomsky's famous 1959 review of B. F. Skinner's Verbal Behavior, a linguistically based paradigm for research in first language acquisition has been strong, even in some senses, dominant. Even Piaget, whose main concern was the nature of cognitive development in general, did not deny the essential claim of a linguistically based paradigm for the study of language acquisition: ‘I (Piaget) also agree with him (Chomsky) on the fact that this rational origin of language presupposes the existence of a fixed nucleus necessary to the elaboration of all languages’ (Piaget in Piatelli-Palmarini, 1980: 57). This linguistically based paradigm has led to a developed theory of what it is that the child must acquire when s/he acquires language, and to precise scientific hypotheses regarding the nature of this knowledge. These hypotheses can be, and are being, subjected to empirical test, thus advancing the scientific foundations of the field. In this paradigm, the postulation of a ‘Language Faculty’ in the mind of the human species, and in the child, has allowed the formulation of specific components of linguistic knowledge which are now being tested in language acquisition as well as in grammars of languages of the world.

Sabbagh & Gelman have written an unusually thorough and careful commentary, and furthermore, I agree with virtually everything they say. Most of what I want to do in this commentary (given the space) is to try to situate these issues in a broader perspective.

To start with, I'll assume that my sympathy for statistical analytic processes as an important part of children's language acquisition is well-established (Maratsos & Chalkley, 1980; Maratsos, 1998), even if I think there are qualifications and limits of some sorts that are necessary (Maratsos, 1998). Simultaneously, I strongly agree with the implications of many of Sabbagh & Gelman's remarks: these mechanisms may be variously biased or specially set for various activities, and probably are not the only thing going on, either.

The review article by S&G seems to me to take a very useful stance: basically friendly but gently quizzical. My linguistics doctoral seminar gave their review the same reception; we enjoyed many of the insights but thought that a few of the assumptions, mostly ones that are common in certain types of language acquisition studies, should be respectfully challenged.

In their very balanced critique of emergentist approaches to language, Sabbagh & Gelman focus on two main issues. The first is the question of whether language acquisition can be explained by domain-general learning mechanisms. The second is the question of the degree of specification that emergentist models of language acquisition actually provide.

For decades, controversy has swirled around the question of whether some kind of innate capacity is required for language to develop normally. Ostensibly, there has been progress over the years on the old ‘nature- nurture’ question. Only the most die-hard theorists would now publicly argue for anything other than some sort of interactionist position. Nonetheless, as Sabbagh & Gelman (S&G) note in their review of The emergence of language, there is little clarity about the nature of that interaction or about what constitutes an emergentist position on it. As good scientists, S&G propose to evaluate emergentism, despite its vagueness, by describing a ‘strong’ emergentist position as one that must include the following tenets: domain-general cognitive processes (‘buzzsaws’ as they call them) like attention and memory are sufficient to account for the elegance of language as well as the ease and speed of its acquisition by children; these domain- general processes do so without explicit rule-based knowledge representations; and the same processes account for all aspects of language. There is much to agree with in the review by S&G. They cite the importance of development and performance as pluses for emergentist views, but they also raise serious questions about the limitations of emergentist accounts: these often either leave unanalyzed crucial concepts like similarity or hide what look suspiciously like rule-governed knowledge representations. Despite their concerns, S&G are gracious in their conclusions; they seem cautiously optimistic about the enterprise of accounting for language development in an emergentist framework. Such optimism, however, seems appropriate only insofar as the framework is not taken in its strong form. S&G's arguments (made by others as well) about the vague and hidden aspects of some emergentist models give the lie to the claim that all aspects of language can be accounted for by the same domain-general processes. Those arguments also raise questions about whether domain-specific rule-based representations can be completely done away with.

The commentaries provide a thoughtful range of responses that reflect the existing theoretical diversity concerning explanations of language development. Below we clarify and amplify a few points from our original review that appeared to have been unclear.