Carla L. Hudson Kam

Regularizing Unpredictable Variation: The Roles of Adult and Child Learners in Language Formation and Change

In this article we investigate what learners acquire when their input contains inconsistent grammatical morphemes such as those present in pidgins and incipient creoles. In particular, we ask if learners acquire variability veridically or if they change it, making the language more regular as they learn it. In Experiment 1 we taught adult participants an artificial language containing unpredictable variation in 1 grammatical feature. We manipulated the amount of inconsistency and the meaning of the inconsistent item. Postexposure testing showed that participants learned the language, including the variable item, despite the presence of inconsistency. However, their use of variable items reflected their input. Participants exposed to consistent patterns produced consistent patterns, and participants exposed to inconsistency reproduced that inconsistency; they did not make the language more consistent. The meaning of the inconsistent item had no effect. In Experiment 2 we taught adults and 5- to 7-year-old children a similar artificial language. As in Experiment 1, the adults did not regularize the language. However, many children did regularize the language, imposing patterns that were not the same as their input. These results suggest that children and adults do not learn from variable input in the same way. Moreover, they suggest that children may play a unique and important role in creole formation by regularizing grammatical patterns.

Getting it right by getting it wrong: When learners change languages

When natural language input contains grammatical forms that are used probabilistically and inconsistently, learners will sometimes reproduce the inconsistencies; but sometimes they will instead regularize the use of these forms, introducing consistency in the language that was not present in the input. In this paper we ask what produces such regularization. We conducted three artificial language experiments, varying the use of determiners in the types of inconsistency with which they are used, and also comparing adult and child learners. In Experiment 1 we presented adult learners with scattered inconsistency - the use of multiple determiners varying in frequency in the same context - and found that adults will reproduce these inconsistencies at low levels of scatter, but at very high levels of scatter will regularize the determiner system, producing the most frequent determiner form almost all the time. In Experiment 2 we showed that this is not merely the result of frequency: when determiners are used with low frequencies but in consistent contexts, adults will learn all of the determiners veridically. In Experiment 3 we compared adult and child learners, finding that children will almost always regularize inconsistent forms, whereas adult learners will only regularize the most complex inconsistencies. Taken together, these results suggest that regularization processes in natural language learning, such as those seen in the acquisition of language from non-native speakers or in the formation of young languages, may depend crucially on the nature of language learning by young children.

Longitudinal Evidence for Functional Specialization of the Neural Circuit Supporting Working Memory in the Human Brain

Although children perform more poorly than adults on many cognitive measures, they are better able to learn things such as language and music. These differences could result from the delayed specialization of neural circuits and asynchronies in the maturation of neural substrates required for learning. Working memory—the ability to hold information in mind that is no longer present in the environment—comprises a set of cognitive processes required for many, if not all, forms of learning. A critical neural substrate for working memory (the prefrontal cortex) continues to mature through early adulthood. What are the functional consequences of this late maturation for working memory? Using a longitudinal design, we show that although individuals recruit prefrontal cortex as expected during both early and late adolescence during a working memory task, this recruitment is correlated with behavior only in late adolescence. The hippocampus is also recruited, but only during early, and not late, adolescence. Moreover, the hippocampus and prefrontal cortex are coactive in early adolescence regardless of task demands or performance, in contrast to the pattern seen in late adolescents and adults, when these regions are coactive only under high task demands. Together, these data demonstrate that neural circuitry underlying working memory changes during adolescent development. The diminishing contribution of the hippocampus in working memory function with age is an important observation that informs questions about how children and adults learn differently.

Co-speech gesture as input in verb learning.

People gesture a great deal when speaking, and research has shown that listeners can interpret the information contained in gesture. The current research examines whether learners can also use co-speech gesture to inform language learning. Specifically, we examine whether listeners can use information contained in an iconic gesture to assign meaning to a novel verb form. Two experiments demonstrate that adults and 2-, 3-, and 4-year-old children can infer the meaning of novel intransitive verbs from gestures when no other source of information is present. The findings support the idea that gesture might be a source of input available to language learners.

When it hurts (and helps) to try: the role of effort in language learning.

Compared to children, adults are bad at learning language. This is counterintuitive; adults outperform children on most measures of cognition, especially those that involve effort (which continue to mature into early adulthood). The present study asks whether these mature effortful abilities interfere with language learning in adults and further, whether interference occurs equally for aspects of language that adults are good (word-segmentation) versus bad (grammar) at learning. Learners were exposed to an artificial language comprised of statistically defined words that belong to phonologically defined categories (grammar). Exposure occurred under passive or effortful conditions. Passive learners were told to listen while effortful learners were instructed to try to 1) learn the words, 2) learn the categories, or 3) learn the category-order. Effortful learners showed an advantage for learning words while passive learners showed an advantage for learning the categories. Effort can therefore hurt the learning of categories.

Investigating the Cause of Language Regularization in Adults: Memory Constraints or Learning Effects?.

When language learners are exposed to inconsistent probabilistic grammatical patterns, they sometimes impose consistency on the language instead of learning the variation veridically. The authors hypothesized that this regularization results from problems with word retrieval rather than from learning per se. One prediction of this, that easing the demands of lexical retrieval leads to less regularization, was tested. Adult learners were exposed to a language containing inconsistent probabilistic patterns and were tested with either a standard production task or one of two tasks that reduced the demands of lexical retrieval. As predicted, participants tested with the modified tasks more closely matched the probability of the inconsistent items than did those tested with the standard task.

Knowing ‘who she is’ based on ‘where she is’: The effect of co-speech gesture on pronoun comprehension

Abstract We examine whether pronoun interpretation is affected by naturalistic co-speech gesture. Participants in three conditions watched narrations containing ambiguous pronouns. In one condition the narrator produced gestures consistent with order-of-mention; in another, they conflicted with order-of-mention; and in the third, she did not gesture. Results showed that when the gestures conflicted with order-of-mention participants were much less likely to interpret the pronoun as referring to the first-mentioned character. In a second experiment we ruled out the possibility that participants were simply picking up on differences within the speech itself. These results extend previous work on gesture and language processing by showing that the information in gesture can influence the way people interpret words which by their nature are ambiguous, and that this influence is similar to that of well-known speech internal cues.

Some Cues Are Stronger Than Others: The (non)interpretation Of 3rd Person Present —s As A Tense Marker By 6- And 7-year-olds

This article describes two experiments examining how 6- and 7-year-old Standard American English-speaking children interpret 3rd person present —s as a tense marker, as compared to lexical items and past tense —ed. Because —s corresponds to multiple meanings, unlike —ed, it may result in later acquisition. Using an offline picture-choice task (Experiment 1), the study found that while all children successfully comprehended —ed, only the 7-year-olds successfully comprehended —s. Eye-tracking measures (Experiment 2) revealed that the 6-year-olds are actually sensitive to —s, but that it is not yet a particularly strong cue for them. The article argues that offline tasks may underestimate childrens developing knowledge.

The use of uh and um by 3- and 4-year-old native English-speaking children: Not quite right but not completely wrong

The delay markers (DMs) uh and um are often used by adult English speakers to indicate that an upcoming pause is due to a speech disruption, not the end of a conversational turn. Moreover, uh and um indicate different degrees of disruption (Clark & Fox Tree, 2002). Thus, it appears that children must learn how to use DMs appropriately. In the current study we examined DM use in elicited speech samples from 24 3- and 4-year-old children. We found that pauses following DMs were longer than those not following a DM, but that there was no difference between the pauses following uh and um. Children at this age, then, appear to understand the basic use of DMs, but do not yet differentiate between them.

The Effect of Sonority on Word Segmentation: Evidence for the Use of a Phonological Universal

It has been well documented how language-specific cues may be used for word segmentation. Here, we investigate what role a language-independent phonological universal, the sonority sequencing principle (SSP), may also play. Participants were presented with an unsegmented speech stream with non-English word onsets that juxtaposed adherence to the SSP with transitional probabilities. Participants favored using the SSP in assessing word-hood, suggesting that the SSP represents a potentially powerful cue for word segmentation. To ensure the SSP influenced the segmentation process (i.e., during learning), we presented two additional groups of participants with either (a) no exposure to the stimuli prior to testing or (b) the same stimuli with pauses marking word breaks. The SSP did not influence test performance in either case, suggesting that the SSP is important for word segmentation during the learning process itself. Moreover, the fact that SSP-independent segmentation of the stimulus occurred (in the latter control condition) suggests that universals are best understood as biases rather than immutable constraints on learning.