Multiple determinants of the productive use of the regular past tense suffix

We offer evidence that the productive use of English regular past tense morphology (e.g., drived) results from competitions among lexical-level features within a single mechanism associative system. W e present error data from: (1) on-line elicited productions by adult native speakers (N = 51), and (2) cormectionist back-propagation networks trained to map stems and past tenses of 552 English verbs. The frequency of regularizations is analyzed in terms of item frequency, stem final alveolar consonant, and similarity in past tense mapping across "friends" and "enemies" in phonologically defined neighborhoods. All items were compiled from a lexicon of 1,191 verbs which represents a near-exhaustive listing of monosyllabic stem-past tense pairs in current American English. Results revealed striking similarities between the hiunan and simulation data. Regularizations were significantly correlated with item frequency, as well as phonological attributes of the stem. Crucially, regularization was a function of phonological similarity to frequent suffixed items, especially for irregulars that normally undergo a vowel-change. These results are incompatible with the view that regularization applies by default, independently of inter-item similarities which support the acquisition and processing of lexical items in associative systems

Spanish-speaking caregivers’ use of referential labels with toddlers is a better predictor of later vocabulary than their use of referential gestures

Variation in how frequently caregivers engage with their children is associated with variation in children’s later language outcomes. One explanation for this link is that caregivers use both verbal behaviors, such as labels, and non-verbal behaviors, such as gestures, to help children establish reference to objects or events in the world. However, few studies have directly explored whether language outcomes are more strongly associated with referential behaviors that are expressed verbally, such as labels, or non-verbally, such as gestures, or whether both are equally predictive. Here, we observed caregivers from 42 Spanish-speaking families in the US engage with their 18-month-old children during 5-min lab-based, play sessions. Children’s language processing speed and vocabulary size were assessed when children were 25 months. Bayesian model comparisons assessed the extent to which the frequencies of caregivers’ referential labels, referential gestures, or labels and gestures together, were more strongly associated with children’s language outcomes than their total numbers of words, or overall talkativeness. The best-fitting models showed that children who heard more referential labels at 18 months were faster in language processing and had larger vocabularies at 25 months. Models including gestures, or labels and gestures together, showed weaker fits to the data. Caregivers’ total words predicted children’s language processing speed, but predicted vocabulary size less well. These results suggest that the frequency with which caregivers of 18-month-old children use referential labels, more so than referential gestures, is a critical feature of caregiver verbal engagement that contributes to language processing development and vocabulary growth

White Matter Plasticity in Reading-Related Pathways Differs in Children Born Preterm and at Term: A Longitudinal Analysis

Children born preterm (PT) are at risk for white matter injuries based on complications of prematurity. They learn to read but on average perform below peers born full term (FT). Studies have yet to establish whether properties of white matter pathways at the onset of learning to read are associated with individual variation later in reading development in PT children. Here, we asked whether fractional anisotropy (FA) at age 6 years is associated with reading outcome at age 8 years in PT children in the same pathways as previously demonstrated in a sample of FT children. PT (n = 34, mean gestational age = 29.5 weeks) and FT children (n = 37) completed diffusion MRI and standardized measures of non-verbal IQ, language, and phonological awareness at age 6 years. Reading skills were assessed at age 8 years. Mean tract-FA was extracted from pathways that predicted reading outcome in children born FT: left arcuate fasciculus (Arc), bilateral superior longitudinal fasciculus (SLF), and left inferior cerebellar peduncle (ICP). We explored associations in additional pathways in the PT children: bilateral inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, and uncinate fasciculus. Linear regression models examined whether the prediction of reading outcome at age 8 years based on mean tract-FA at age 6 years was moderated by birth group. Children born PT and FT did not differ significantly in tract-FA at age 6 years or in reading at age 8 years. Sex, socioeconomic status, and non-verbal IQ at age 6 years were associated with reading outcome and were included as covariates in all models. Birth group status significantly moderated associations between reading outcome and mean tract-FA only in the left Arc, right SLF, and left ICP, before and after consideration of pre-literacy skills. Microstructural properties of these cerebral and cerebellar pathways predicted later reading outcome in FT but not in PT children. Children born PT may rely on alternative pathways to achieve fluent reading. These findings have implications for plasticity of neural organization after early white matter injury

LENA its data collected in Kaolack Senegal in 2013

This project contains data and metadata from LENA recordings collected in principally Wolof-speaking villages in rural Kaolack Senegal in 2013. Funding for this work was received from the William and Flora Hewlett Foundation

Overregularization in English plural and past tense inflectional morphology: a response to Marcus (1995)

In a recent note, Marcus (1995) suggests that the rate of overregularization of English irregular plural nouns is not substantially different from that of English irregular past tense verbs. This finding is claimed to be in conflict with the predictions of connectionist models (Plunkett & Marchman, 1991, 1993) which are said to depend solely on the dominance of regular over irregular forms in determining overregulation errors. However, these conclusions may be premature given that Marcus averaged overregulation rates across irregular nominal forms that varied in token frequency and across samples representing a broad range of children's ages. A connectionist view would predict an interplay between type frequency and other item level factors, e.g. token frequency, as well as differences in the developmental trajectories of the acquisition of nouns and verbs. In this response, we briefly review longitudinal parental report data (N=26) which indicate that children are significantly more likely to produce noun overregularizations than verb overregularizations across a prescribed age period (1;5 to 2;6). At the same time, these data also show that children are familiar with proportionately more irregular nouns that irregular verbs. These findings are consistent with the predictions of Plunkett & Marchman (1991, 1993) in that the larger regular class affects the frequency of noun errors but also that familiarity with individual irregular nouns tends to reduce the likelihood of overregularizations. In contrast to the conclusion of Marcus (1995), the connectionist approach to English inflectional morphology provides a plausible explanation of the phenomenon of overregularization in both the English plural and past tense systems