The acquisition of the English past tense inflection is the paradigm example of rule learning in the child language literature and has become something of a test case for theories of language development. This is unfortunate, as the idiosyncratic properties of the English system of marking tense make it a rather unrepresentative example of morphological development. In this paper, I contrast this familiar inflection with a much more complex morphological subsystem, the Polish genitive. The genitive case has three different markers, each restricted to a different subset of nouns, in both the singular and the plural. Analysis of the spontanous speech of three children between the ages of 1;4 and 4;11 showed that they generalized, and overgeneralized, all three singular endings. However, error rates were extremely low and there is no evidence that they treated any one ending as the ‘default’. The genitive plural, on the other hand, showed a strikingly different pattern of acquisition, similar to that seen in English-speaking children learning the past tense. It is argued that in the latter two cases, the default-like character of one of the affixes is attributable to the properties of the relevant inflectional subsystems, not to the predispositions that children bring to the language-learning task.

The artificial language Esperanto is spoken not only as a second language, by its proponents, but also as a native language by children of some of those proponents. The present study is a preliminary description of some characteristics of the Native Esperanto (NE) of eight speakers, ranging in age from six to fourteen years. As such, it is the first of its kind – previous works on NE are either theoretical treatises or individual case studies. We find, at least for the eight subjects studied, both bilingualism and nativization effects, differentiating native from non-native Esperanto speech. Among these effects are loss or modification of the accusative case, phonological reduction, attrition of the tense/aspect system, and pronominal cliticization. The theoretical ramifications are discussed, particularly with regard to universals of language acquisition and the effects of expressive requirements of language.

Two common and seemingly independent error patterns, namely CONSONANT HARMONY and GLIDING, are examined for their typological characteristics based on cross-sectional and longitudinal evidence from young children's developing phonologies. Data are drawn from the published literature and from the developmental phonology archives at Indiana University. An asymmetry is observed such that the occurrence of harmony is found to imply the occurrence of gliding, but not vice versa. While this finding would be unexpected within contemporary derivational theories, it can be shown to follow within optimality theory from a fixed universal ranking relationship among certain constraints. Optimality theory is also argued to offer a viable developmental account with clinical implications that can serve as a further test of the theory.

Children who acquire Dutch as their first language show a strong preference for using infinitival verb forms during the early stages of grammatical development. This exemplifies the ‘root infinitive’ (RI) phenomenon, which has played a significant role in recent discussions on the development of syntax. Most accounts proposed thus far invoke an immaturity of the child's grammatical competence. We explore the possibility that the early predominance of infinitival forms is related to patterns in the language input. We analysed a corpus of utterances addressed by two Dutch-speaking mothers to their two- to three-year old sons. Root infinitive utterances amounted to 10%, and auxiliary-plus infinitive main verb constructions, which in terms of word order are maximally similar to RIs, constituted 30% of all verb-containing utterances. These figures render an account in terms of exposure to utterance structures unlikely. There is a moderate (but significant) correlation between frequency of occurrence of individual verb forms in the input and age of acquisition. However, infinitive verb forms are often acquired earlier than their input frequency would predict, and this may be related to an overall increased salience, due to their systematic appearance in sentence-final position and their relatively high conceptual transparency as compared to finite verbs.

This study investigated the ASPECT FIRST HYPOTHESIS which claims that children initially use verbal morphology to mark aspect and not tense. Experiment 1 tested 46 two- and three-year-old children's comprehension of tense as it is marked in the auxiliary system using a sentence-to-scene matching task. Children were presented with multiple performances of the same event and asked where a character is V'ing, was V'ing and is gonna V. Results showed that even the two-year-old children could successfully understand tense in this experiment. Experiment 2 changed the information available in the scenes by varying whether or not the past-time event reached its completion point. Thirty-six two-, three- and four-year-old children participated. The results showed that the two-year-olds could only successfully understand past and present auxiliaries when past-time information in the scenes was co-extensive with completion information in the scenes. This result suggests that these children may be making a grammatical aspect (perfective/imperfective) judgment and not a tense (past/present) judgment, or at least, that grammatical aspect influences tense interpretation for these children.

Animals are distinctive in that they are the causal agents of their own actions (e.g. a dog moves itself), whereas artifacts generally are not (e.g. a marble doesn't move itself). We examined whether children make use of this conceptual link between animacy and agency when interpreting the verb ‘move’ in English. Specifically, we hypothesized that the semantic interpretation of ‘move’ would differ, depending on whether the subject noun refers to an animal or to an inanimate object. We hypothesized that, for inanimates, children would allow ‘move’ to have a patient subject (e.g. ‘the marble moved’ could mean ‘the marble was moved by someone else’) but not so for animates (e.g. ‘the dog moved’ could not mean ‘the dog was moved by someone else’). In two studies, 65 three-year-olds, 57 five-year-olds, and 74 adults viewed video clips of animals or inanimate objects being transported by a person. For each clip, the child was asked whether the animal or object was moving. A ‘yes’ response would indicate acceptance of a patient subject (e.g. ‘the dog/marble moved’ means ‘the dog/marble was moved by someone else’). Both five-year-old children and adults more often reported that the toys were moving, than that the animals were moving. However, three-year-olds showed no animacy effects. Thus, between the ages of three and five, children begin to link animacy and agency in language. These findings suggest that children's language use is guided by similar conceptual constraints as those of adults, and/or that children are sensitive to distributional information linking form and meaning in the input language.

The development of metalinguistic awareness, and specifically syntactic awareness, (here measured by age-related changes in the ability to judge and revise unacceptable sentences), reflects developmental changes in focus from semantic to syntactic properties of sentences. Previous research reported that children find judgements of word-order changes easier than morphological violations (Hakes, 1980). We hypothesized that this difference in ease of judgement is linked to the language under investigation. That is, there may be a relationship between the functional load of grammatical morphemes and ability to detect syntactic violations. This study investigated the development of syntactic awareness in Cantonese-speaking children. Fifty-six subjects from four age groups (three, five, seven and 20 years old) were asked to judge the grammaticality of 40 sentences (18 with word-order changes and 22 with morphological violations) and correct the grammatically deviant sentences. There was a significant age effect on subjects’ performance in both judgement and revision tasks. Children scored significantly higher in judging sentences with word order changes than those with morphological violations. They also scored higher on word order revisions than morphological revisions, an unexpected finding. The success of correcting morphological violations varied by morphological marker, apparently according to each marker's degree of obligatory use in the language. It would seem then that syntactic awareness is very much affected by language-specific characteristics.

This study had two major objectives: (1) to analyse the development of two morphological structures in Hebrew, one inflectional and the other derivational and (2) to examine the mutual contribution of morphological knowledge and learning the written code. In a longitudinal design, 40 children were tested twice, first in kindergarten (mean age: 5; 11) and again in first grade (mean age: 6;5), on two oral tasks – inflecting nouns for possession and deriving denominal adjectives – and one written task of writing a series of noun-adjective pairs. The derivational task was found to be harder than the inflectional task, both on the stem and the suffix level, attributable to its higher semantic opacity. In both oral tests, correct stem production when suffixed was related to the morphophonological level of stem change. Correlations were found between morphological and writing scores. Moreover, children who were more advanced in morphology in kindergarten progressed more in writing vowels from kindergarten to first grade, and those who were more advanced in writing in kindergarten improved more in derivational morphology with grade.

This paper examines naturalistic adult-to-child speech produced by 15 Italian middle-class mothers to determine which specific patterns characterize linguistic input to children at 1;4 and 1;8. Since Italian is a PRO-DROP language, we expect that adult-to-child speech will show a bias towards a more salient semantic and morphological significance of verbs relative to nouns. We expect that verbs will more likely occupy the sentence-initial position, and have more morphological inflections relative to nouns. Mother-to-child speech was coded for type and token frequency, utterance position, and morphological variation of nouns and verbs. The results confirm our predictions. Namely, Italian-speaking mothers produced verb types and tokens more frequently than noun types and tokens, they placed verbs more frequently than nouns in salient utterance position, and they morphologically marked verb stems more than noun stems.

Two experiments investigated why preschool children sometimes produce multiple words for a referent (i.e. POLYNOMY), but other times seem to allow only one word. In Experiment 1, 40 three- and four-year-olds completed a modification of Deák & Maratsos' (1998) naming task. Although social demands to produce multiple words were reduced, children produced, on average, more than two words per object. Number of words produced was predicted by receptive vocabulary. Lexical insight (i.e. knowing that a word refers to function or appearance) and metalexical beliefs (i.e. that a hypothetical referent has one label, or more than one) were not preconditions of polynomy. Polynomy was independent of bias to map novel words to unfamiliar referents. In Experiment 2, 40 three- and four-year-olds learned new words for nameable objects. Children showed a correction effect, yet produced more than two words per object. Children do not have a generalized one-word-per-object bias, even during word learning. Other explanations (e.g. contextual restriction of lexical access) are discussed.