Children's Acquisition of the English Past-Tense: Evidence for a Single-Route Account From Novel Verb Production Data.

This study adjudicates between two opposing accounts of morphological productivity, using English past-tense as its test case. The single-route model (e.g., Bybee & Moder, ) posits that both regular and irregular past-tense forms are generated by analogy across stored exemplars in associative memory. In contrast, the dual-route model (e.g., Prasada & Pinker, ) posits that regular inflection requires use of a formal "add -ed" rule that does not require analogy across regular past-tense forms. Children (aged 3-4; 5-6; 6-7; 9-10) saw animations of an animal performing a novel action described with a novel verb (e.g., gezz; chake). Past-tense forms of novel verbs were elicited by prompting the child to describe what the animal "did yesterday." Collapsing across age group (since no interaction was observed), the likelihood of a verb being produced in regular past-tense form (e.g., gezzed; chaked) was positively associated with the verb's similarity to existing regular verbs, consistent with the single-route model only. Results indicate that children's acquisition of the English past-tense is best explained by a single-route analogical mechanism that does not incorporate a role for formal rules.

A connectionist model of the retreat from verb argument structure overgeneralization.

A central question in language acquisition is how children build linguistic representations that allow them to generalize verbs from one construction to another (e.g., The boy gave a present to the girl → The boy gave the girl a present), whilst appropriately constraining those generalizations to avoid non-adultlike errors (e.g., I said no to her → *I said her no). Although a consensus is emerging that learners solve this problem using both statistical and semantics-based learning procedures (e.g., entrenchment, pre-emption, and semantic verb class formation), there currently exist few - if any - proposals for a learning model that combines these mechanisms. The present study used a connectionist model to test an account that argues for competition between constructions based on (a) verb-in construction frequency, (b) relevance of constructions for the speaker's intended message, and (c) fit between the fine-grained semantic properties of individual verbs and individual constructions. The model was able not only (a) to simulate the overall pattern of overgeneralization-then-retreat, but also (b) to use the semantics of novel verbs to predict their argument structure privileges (just as real learners do), and

Children use statistics and semantics in the retreat from overgeneralization.

How do children learn to restrict their productivity and avoid ungrammatical utterances? The present study addresses this question by examining why some verbs are used with un- prefixation (e.g., unwrap) and others are not (e.g., *unsqueeze). Experiment 1 used a priming methodology to examine children's (3-4; 5-6) grammatical restrictions on verbal un- prefixation. To elicit production of un-prefixed verbs, test trials were preceded by a prime sentence, which described reversal actions with grammatical un- prefixed verbs (e.g., Marge folded her arms and then she unfolded them). Children then completed target sentences by describing cartoon reversal actions corresponding to (potentially) un- prefixed verbs. The younger age-group's production probability of verbs in un- form was negatively related to the frequency of the target verb in bare form (e.g., squeez/e/ed/es/ing), while the production probability of verbs in un- form for both age groups was negatively predicted by the frequency of synonyms to a verb's un- form (e.g., release/*unsqueeze). In Experiment 2, the same children rated the grammaticality of all verbs in un- form. The older age-group's grammaticality judgments were (a) positively predicted by the extent to which each verb was semantically consistent with a semantic "cryptotype" of meanings - where "cryptotype" refers to a covert category of overlapping, probabilistic meanings that are difficult to access - hypothesised to be shared by verbs which take un-, and (b) negatively predicted by the frequency of synonyms to a verb's un- form. Taken together, these experiments demonstrate that children as young as 4;0 employ pre-emption and entrenchment to restrict generalizations, and that use of a semantic cryptotype to guide judgments of overgeneralizations is also evident by age 6;0. Thus, even early developmental accounts of children's restriction of productivity must encompass a mechanism in which a verb's semantic and statistical properties interact.