The evolution of frequency distributions: Relating regularization to inductive biases through iterated learning

The regularization of linguistic structures by learners has played a key role in arguments for strong innate constraints on language acquisition, and has important implications for language evolution. However, relating the inductive biases of learners to regularization behavior in laboratory tasks can be challenging without a formal model. In this paper we explore how regular linguistic structures can emerge from language evolution by iterated learning, in which one person’s linguistic output is used to generate the linguistic input provided to the next person. We use a model of iterated learning with Bayesian agents to show that this process can result in regularization when learners have the appropriate inductive biases. We then present three experiments demonstrating that simulating the process of language evolution in the laboratory can reveal biases towards regularization that might not otherwise be obvious, allowing weak biases to have strong effects. The results of these experiments suggest that people tend to regularize inconsistent word-meaning mappings, and that even a weak bias towards regularization can allow regular languages to be produced via language evolution by iterated learning.     

Acquiring variation in an artificial language: Children and adults are sensitive to socially conditioned linguistic variation

Languages exhibit sociolinguistic variation, such that adult native speakers condition the usage of linguistic variants on social context, gender, and ethnicity, among other cues. While the existence of this kind of socially conditioned variation is well-established, less is known about how it is acquired. Studies of naturalistic language use by children provide various examples where children’s production of sociolinguistic variants appears to be conditioned on similar factors to adults’ production, but it is difficult to determine whether this reflects knowledge of sociolinguistic conditioning or systematic differences in the input to children from different social groups. Furthermore, artificial language learning experiments have shown that children have a tendency to eliminate variation, a process which could potentially work against their acquisition of sociolinguistic variation. The current study used a semi-artificial language learning paradigm to investigate learning of the sociolinguistic cue of speaker identity in 6-year-olds and adults. Participants were trained and tested on an artificial language where nouns were obligatorily followed by one of two meaningless particles and were produced by one of two speakers (one male, one female). Particle usage was conditioned deterministically on speaker identity (Experiment 1), probabilistically (Experiment 2), or not at all (Experiment 3). Participants were given tests of production and comprehension. In Experiments 1 and 2, both children and adults successfully acquired the speaker identity cue, although the effect was stronger for adults and in Experiment 1. In addition, in all three experiments, there was evidence of regularization in participants’ productions, although the type of regularization differed with age: children showed regularization by boosting the frequency of one particle at the expense of the other, while adults regularized by conditioning particle usage on lexical items. Overall, results demonstrate that children and adults are sensitive to speaker identity cues, an ability which is fundamental to tracking sociolinguistic variation, and that children’s well-established tendency to regularize does not prevent them from learning sociolinguistically conditioned variation.     

Regularization of languages by adults and children: A mathematical framework

The fascinating ability of humans to modify the linguistic input and “create” a language has been widely discussed. In the work of Newport and colleagues, it has been demonstrated that both children and adults have some ability to process inconsistent linguistic input and “improve” it by making it more consistent. In Hudson Kam and Newport (2009), artificial miniature language acquisition from an inconsistent source was studied. It was shown that (i) children are better at language regularization than adults and that (ii) adults can also regularize, depending on the structure of the input. In this paper we create a learning algorithm of the reinforcement-learning type, which exhibits patterns reported in Hudson Kam and Newport (2009) and suggests a way to explain them. It turns out that in order to capture the differences between children’s and adults’ learning patterns, we need to introduce a certain asymmetry in the learning algorithm. Namely, we have to assume that the reaction of the learners differs depending on whether or not the source’s input coincides with the learner’s internal hypothesis. We interpret this result in the context of a different reaction of children and adults to implicit, expectation-based evidence, positive or negative. We propose that a possible mechanism that contributes to the children’s ability to regularize an inconsistent input is related to their heightened sensitivity to positive evidence rather than the (implicit) negative evidence. In our model, regularization comes naturally as a consequence of a stronger reaction of the children to evidence supporting their preferred hypothesis. In adults, their ability to adequately process implicit negative evidence prevents them from regularizing the inconsistent input, resulting in a weaker degree of regularization.     

The italian determiner system in normal acquisition, specific language impairment, and childhood aphasia

The paper presents a comparison of the development of the Italian determiner system in three different populations: normally developing children, a child recovering from childhood aphasia from the age of 3 years, 9 months, and 11 specific language impairment (SLI) children. Data from Italian normal children provide evidence for the hypothesis (1) that no prefunctional stage exists as far as the determiner system is concerned and (2) that the syntactic properties of determiners play an essential triggering role early on. The analysis of the determiner system in the aphasic child has a double interest. On the one hand, it may help to shed light on some of the intriguing questions concerning this type of disorder; on the other, it may be relevant for the discussion of the notion of agrammatism. Results of the morphosyntactic analysis reveal that, apart from timing differences, recovery from childhood aphasia shares important features with normal development. Differently from mean length of utterance (MLU)-matched normal controls and the aphasic child, SLI children omit determiners significantly more often than almost any other functional category or free morpheme. We will argue that the reasons for the SLI children's atypical behavior have to be sought in the nonaccessibility to or in the misappreciation of one fundamental syntactic property of determiners: their role as elements that assign argumenthood to nominal expressions (Szabolcsi, 1987; Longobardi, 1994).     

Word frequency as a cue for identifying function words in infancy

While content words (e.g., ‘dog’) tend to carry meaning, function words (e.g., ‘the’) mainly serve syntactic purposes. Here, we ask whether 17-month old infants can use one language–universal cue to identify function word candidates: their high frequency of occurrence. In Experiment 1, infants listened to a series of short, naturally recorded sentences in a foreign language (i.e., in French). In these sentences, two determiners appeared much more frequently than any content word. Following this, infants were presented with a visual object, and simultaneously with a word pair composed of a determiner and a noun. Results showed that infants associated the object more strongly with the infrequent noun than with the frequent determiner. That is, when presented with both the old object and a novel object, infants were more likely to orient towards the old object when hearing a label with a new determiner and the old noun compared to a label with a new noun and the old determiner. In Experiment 2, infants were tested using the same procedure as in Experiment 1, but without the initial exposure to French sentences. Under these conditions, infants did not preferentially associate the object with nouns, suggesting that the preferential association between nouns and objects does not result from specific acoustic or phonological properties. In line with various biases and heuristics involved in acquiring content words, we provide the first direct evidence that infants can use distributional cues, especially the high frequency of occurrence, to identify potential function words.     

Object‐Label‐Order Effect When Learning From an Inconsistent Source

Learning in natural environments is often characterized by a degree of inconsistency from an input. These inconsistencies occur, for example, when learning from more than one source, or when the presence of environmental noise distorts incoming information; as a result, the task faced by the learner becomes ambiguous. In this study, we investigate how learners handle such situations. We focus on the setting where a learner receives and processes a sequence of utterances to master associations between objects and their labels, where the source is inconsistent by design: It uses both “correct” and “incorrect” object‐label pairings. We hypothesize that depending on the order of presentation, the result of the learning may be different. To this end, we consider two types of symbolic learning procedures: the Object‐Label (OL) and the Label‐Object (LO) process. In the OL process, the learner is first exposed to the object, and then the label. In the LO process, this order is reversed. We perform experiments with human subjects, and also construct a computational model that is based on a nonlinear stochastic reinforcement learning algorithm. It is observed experimentally that OL learners are generally better at processing inconsistent input compared to LO learners. We show that the patterns observed in the learning experiments can be reproduced in the simulations if the model includes (a) an ability to regularize the input (and also to do the opposite, i.e., undermatch) and (b) an ability to take account of implicit negative evidence (i.e., interactions among different objects/labels). The model suggests that while both types of learners utilize implicit negative evidence in a similar way, there is a difference in regularization patterns: OL learners regularize the input, whereas LO learners undermatch. As a result, OL learners are able to form a more consistent system of image‐utterance associations, despite the ambiguous learning task.     

A purple giraffe is faster than a purple elephant: Inconsistent phonology affects determiner selection in English

The form of a determiner is dependent on different contextual factors: in some languages grammatical number and grammatical gender determine the choice of a determiner variant. In other languages, the phonological onset of the element immediately following the determiner affects selection, too. Previous work has shown that the activation of opposing determiner forms by a noun’s grammatical properties leads to slower naming latencies in a picture naming task, as does the activation of opposing forms by the interaction between a noun’s gender and the phonological context. The present paper addresses the question of whether phonological context alone is sufficient to evoke competition between determiner forms. Participants produced English phrases in which a noun phrase’s phonology required a determiner that was the same as or differed from the determiner required by the noun itself (e.g., a purple giraffe; an orange giraffe). Naming latencies were slower when the phrase-initial determiner differed from the determiner required by the noun in isolation than when the phrase-initial determiner matched the isolated-noun determiner. This was true both for definite and indefinite determiners. The data show that during the production of a determiner–noun phrase, nouns automatically activate the phonological forms of their determiners, which can compete with the phonological forms that are generated by an assimilation rule.     

When learners surpass their models: the acquisition of American Sign Language from inconsistent input

The present study examines the impact of highly inconsistent input on language acquisition. The American deaf community provides a unique opportunity to observe children exposed to nonnative language models as their only linguistic input. This research is a detailed case study of one child acquiring his native language in such circumstances. It asks whether this child is capable of organizing a natural language out of input data that are not representative of certain natural language principles. Simon is a deaf child whose deaf parents both learned American Sign Language (ASL) after age 15. Simon's only ASL input is provided by his late-learner parents. The study examines Simon's performance at age 7 on an ASL morphology task, compared with eight children who have native signing parents, and also compared with Simon's own parents. The results show that Simon's production of ASL substantially surpasses that of his parents. Simon's parents, like other late learners of ASL, perform below adult native signing criteria, with many inconsistencies and errors in their use of ASL morphology. In contrast, Simon's performance is much more regular, and in fact on most ASL morphemes is equal to that of children exposed to a native signing model. The results thus indicate that Simon is capable of acquiring a regular and orderly morphological rule system for which his input provides only highly inconsistent and noisy data. In addition, the results provide some insight into the mechanisms by which such learning may occur. Although the ASL situation is rare, it reveals clues that may contribute to our understanding of the human capacity for language learning.     

Tracking Multiple Statistics: Simultaneous Learning of Object Names and Categories in English and Mandarin Speakers

Two experiments were conducted to examine adult learners' ability to extract multiple statistics in simultaneously presented visual and auditory input. Experiment 1 used a cross‐situational learning paradigm to test whether English speakers were able to use co‐occurrences to learn word‐to‐object mappings and concurrently form object categories based on the commonalities across training stimuli. Experiment 2 replicated the first experiment and further examined whether speakers of Mandarin, a language in which final syllables of object names are more predictive of category membership than English, were able to learn words and form object categories when trained with the same type of structures. The results indicate that both groups of learners successfully extracted multiple levels of co‐occurrence and used them to learn words and object categories simultaneously. However, marked individual differences in performance were also found, suggesting possible interference and competition in processing the two concurrent streams of regularities.     

Effects of visual information on adults' and infants' auditory statistical learning

Infant and adult learners are able to identify word boundaries in fluent speech using statistical information. Similarly, learners are able to use statistical information to identify word-object associations. Successful language learning requires both feats. In this series of experiments, we presented adults and infants with audio-visual input from which it was possible to identify both word boundaries and word-object relations. Adult learners were able to identify both kinds of statistical relations from the same input. Moreover, their learning was actually facilitated by the presence of two simultaneously present relations. Eight-month-old infants, however, do not appear to benefit from the presence of regular relations between words and objects. Adults, like 8-month-olds, did not benefit from regular audio-visual correspondences when they were tested with tones, rather than linguistic input. These differences in learning outcomes across age and input suggest that both developmental and stimulus-based constraints affect statistical learning.     

Idiomatic syntactic constructions and language learning

This article explores the influence of idiomatic syntactic constructions (i.e., constructions whose phrase structure rules violate the rules that underlie the construction of other kinds of sentences in the language) on the acquisition of phrase structure. In Experiment 1, participants were trained on an artificial language generated from hierarchical phrase structure rules. Some participants were given exposure to an idiomatic construction (IC) during training, whereas others were not. Under some circumstances, the presence of an idiomatic construction in the input aided learners in acquiring the phrase structure of the language. Experiment 2 provides a replication of the first experiment and extends the findings by showing that idiomatic constructions that strongly violate the predictive dependencies that define the phrase structure of the language do not aid learners in acquiring the structure of the language. Together, our data suggest that (a) idiomatic constructions aid learners in acquiring the phrase structure of a language by highlighting relevant structural elements in the language, and (b) such constructions are useful cues to learning to the extent that learners can keep their knowledge of the idiomatic construction separate from their knowledge of the rest of the language.     

Cross-language activation in children's speech production: evidence from second language learners, bilinguals, and trilinguals

In five experiments, we examined cross-language activation during speech production in various groups of bilinguals and trilinguals who differed in nonnative language proficiency, language learning background, and age. In Experiments 1, 2, 3, and 5, German 5- to 8-year-old second language learners of English, German-English bilinguals, German-English-Language X trilinguals, and adult German-English bilinguals, respectively, named pictures in German and in English; in Experiment 4, 6- to 8-year-old German monolinguals named pictures in German. In both language conditions, cognate status was manipulated. We found that the bidirectional cognate facilitation effect was significant in all groups except the German monolinguals (Experiment 4) and, critically, the child second language learners (Experiment 1) in whom only native language (L1) German had an effect on second language (L2) English. The findings demonstrate how the integration of languages into a child's system follows a developmental path that, at lower levels of proficiency, allows only limited cross-language activation. The results are interpreted against the backdrop of the developing language systems of the children both for early second language learners and for early bi- and trilinguals.     

An approach to the study of determiners in early language development

The definite and indefinite articles (the and a) are usually regarded as being a contrastive system. Either the or a is required with a noun, depending on certain semantic and pragmatic considerations. Developmental research views the child as progressively attaining appropriate (adult) use of the two forms. However, both historical and recent developmental evidence indicates that the articles should be incorporated into a total system of determination, including both verbal and nonverbal determiners. A single experiment is described to show 3-year-old children's use of the articles (and other determiners). Several functions of the articles within the two conditions of the experimental context were elicited, as were other verbal (e.g., this, that) and nonverbal (e.g., a point) determiners. It is argued that instead of regarding the child's use of the articles as correct or incorrect, we should look at the form and function of those determiners used and omitted and consider why they are elicited.     

Mapping Word to World in ASL: Evidence from a Human Simulation Paradigm

Across languages, children map words to meaning with great efficiency, despite a seemingly unconstrained space of potential mappings. The literature on how children do this is primarily limited to spoken language. This leaves a gap in our understanding of sign language acquisition, because several of the hypothesized mechanisms that children use are visual (e.g., visual attention to the referent), and sign languages are perceived in the visual modality. Here, we used the Human Simulation Paradigm in American Sign Language (ASL) to determine potential cues to word learning. Sign-naïve adult participants viewed video clips of parent–child interactions in ASL, and at a designated point, had to guess what ASL sign the parent produced. Across two studies, we demonstrate that referential clarity in ASL interactions is characterized by access to information about word class and referent presence (for verbs), similarly to spoken language. Unlike spoken language, iconicity is a cue to word meaning in ASL, although this is not always a fruitful cue. We also present evidence that verbs are highlighted well in the input, relative to spoken English. The results shed light on both similarities and differences in the information that learners may have access to in acquiring signed versus spoken languages.     

Facilitation effects of gender-congruency in the production of Italian clitic pronouns

Psycholinguistic research has shown that the visibility of the gender-congruency effect in noun-phrase production is language-constrained. Those languages (e.g., German) for which the determiner may be selected as early as the gender information is available (“early-selection languages”) show the effect. Those languages (e.g., Italian) for which the selection of the determiner also depends on phonological information of the following noun (“late-selection languages”) do not show any effect. However, there may be gender-marked forms, different from determiners, that meet the requisites for early selection, independently from the language to which they belong. In the picture–word interference experiment reported here we asked whether the production of gender-marked Italian pronouns, by virtue of requiring only gender information for their selection, may be sensitive to the gender-congruency effect. Results showed that participants were faster when the distractor was gender-congruent vs. incongruent with respect to the picture name. This finding supports the view that the visibility of the gender-congruency effect depends on the selection properties (early vs. late) of a given condition rather than of the language itself.     

Language growth with experience without feedback

The relationship between language input and the precise way the child makes use of that input is a complex problem. Most research has concentrated on specific forms in the input and their later production by the child. It may be, however, that the child controls more of the acquisition process than previous input studies have assumed. Experience of particular language forms may be all that is required for internal organizational processes to operate. This longitudinal study investigated language growth in children using a structure they had not yet mastered. Experience of this structure at 3-month intervals over the course of 1 year—without any feedback that children were interpreting some instances incorrectly—led to accelerated acquisition as compared with the ages observed in children tested cross-sectionally. It is argued that exposure to a linguistic structure that induces the child to operate on that structure can lead to a reorganization of linguistic knowledge even though no direct feedback has been given as to its correct adult interpretation.     

Determiner selection in noun phrase production

In 3 experiments, native speakers of German named pictures of 1 or 2 objects by producing singular or plural noun phrases consisting of a definite gender-marked determiner and a noun. When singular and plural determiners differed (masculine and neuter gender), naming latencies were longer for plural utterances than for singular utterances. By contrast, when singular and plural determiners were identical (feminine gender), no such effect was obtained. When participants produced bare nouns, the Gender x Number interaction disappeared. This pattern indicates that during the production of plural definite-determiner noun phrases, singular and plural determiners compete for selection. The resulting constraints on number and gender processing in noun phrase production are discussed in the framework of models of language production.     

Tracking irregular morphophonological dependencies in natural language: evidence from the acquisition of subject-verb agreement in French

This study examines French-learning infants’ sensitivity to grammatical non-adjacent dependencies involving subject-verb agreement (e.g., le/les garçons lit/lisent ‘the boy(s) read(s)’) where number is audible on both the determiner of the subject DP and the agreeing verb, and the dependency is spanning across two syntactic phrases. A further particularity of this subsystem of French subject-verb agreement is that number marking on the verb is phonologically highly irregular. Despite the challenge, the HPP results for 24- and 18-month-olds demonstrate knowledge of both number dependencies: between the singular determiner le and the non-adjacent singular verbal forms and between the plural determiner les and the non-adjacent plural verbal forms. A control experiment suggests that the infants are responding to known verb forms, not phonological regularities. Given the paucity of such forms in the adult input documented through a corpus study, these results are interpreted as evidence that 18-month-olds have the ability to extract complex patterns across a range of morphophonologically inconsistent and infrequent items in natural language.     

汉字频率和构词数对非汉字圈学生汉字学习的影响

探讨汉字频率和构词数对非汉字文化圈的留学生汉字学习效果的影响。实验要求被试对已学过的不同频率和构词数的汉字写出拼音并组词,结果显示,汉字频率对汉字学习效果有影响,而且频率效应的大小受笔画数的制约;实验未发现构词数对汉字学习效果的影响。研究结果表明,语言输入的频率是影响汉语习得的一个重要因素     

Acquiring and processing verb argument structure: distributional learning in a miniature language

Adult knowledge of a language involves correctly balancing lexically-based and more language-general patterns. For example, verb argument structures may sometimes readily generalize to new verbs, yet with particular verbs may resist generalization. From the perspective of acquisition, this creates significant learnability problems, with some researchers claiming a crucial role for verb semantics in the determination of when generalization may and may not occur. Similarly, there has been debate regarding how verb-specific and more generalized constraints interact in sentence processing and on the role of semantics in this process. The current work explores these issues using artificial language learning. In three experiments using languages without semantic cues to verb distribution, we demonstrate that learners can acquire both verb-specific and verb-general patterns, based on distributional information in the linguistic input regarding each of the verbs as well as across the language as a whole. As with natural languages, these factors are shown to affect production, judgments and real-time processing. We demonstrate that learners apply a rational procedure in determining their usage of these different input statistics and conclude by suggesting that a Bayesian perspective on statistical learning may be an appropriate framework for capturing our findings.