Understanding words in context: A naturalistic EEG study of children's lexical processing.

When listening to speech, adults rely on context to anticipate upcoming words. Evidence for this comes from studies demonstrating that the N400, an event-related potential (ERP) that indexes ease of lexical-semantic processing, is influenced by the predictability of a word in context. We know far less about the role of context in children's speech comprehension. The present study explored lexical processing in adults and 5-10-year-old children as they listened to a story. ERPs time-locked to the onset of every word were recorded. Each content word was coded for frequency, semantic association, and predictability. In both children and adults, N400s reflect word predictability, even when controlling for frequency and semantic association. These findings suggest that both adults and children use top-down constraints from context to anticipate upcoming words when listening to stories.

Assessing two methods of webcam-based eye-tracking for child language research.

We assess the feasibility of conducting web-based eye-tracking experiments with children using two methods of webcam-based eye-tracking: automatic gaze estimation with the WebGazer.js algorithm and hand annotation of gaze direction from recorded webcam videos. Experiment 1 directly compares the two methods in a visual-world language task with five to six year-old children. Experiment 2 more precisely investigates WebGazer.js' spatiotemporal resolution with four to twelve year-old children in a visual-fixation task. We find that it is possible to conduct web-based eye-tracking experiments with children in both supervised (Experiment 1) and unsupervised (Experiment 2) settings - however, the webcam eye-tracking methods differ in their sensitivity and accuracy. Webcam video annotation is well-suited to detecting fine-grained looking effects relevant to child language researchers. In contrast, WebGazer.js gaze estimates appear noisier and less temporally precise. We discuss the advantages and disadvantages of each method and provide recommendations for researchers conducting child eye-tracking studies online.

It's All in the Interaction: Early Acquired Words Are Both Frequent and Highly Imageable.

Prior studies have found that children are more likely to learn words that are frequent in the input and highly imageable. Many theories of word learning, however, predict that these variables should interact, particularly early in development: frequency of a form is of little use if you cannot infer its meaning, and a concrete word cannot be acquired if you never hear it. The present study explores this interaction, how it changes over time and its relationship to syntactic category effects in children acquiring American English. We analyzed 1461 monolingual English-speaking children aged 1;4-2;6 from the MB-CDI norming study (Fenson et al., 1994). Word frequency was estimated from the CHILDES database, and imageability was measured using adult ratings. There was a strong over-additive interaction between frequency and imageability, such that children were more likely to learn a word if it was both highly imageable and very frequent. This interaction was larger in younger children than in older children. There were reliable differences between syntactic categories independent of frequency and imageability, which did not interact with age. These findings are consistent with theories in which children's early words are acquired by mapping frequent word forms onto concrete, perceptually available referents, such that highly frequent items are only acquired if they are also imageable, and vice versa.

Potentially recursive structures emerge quickly when a new language community forms.

Human languages can express an infinite number of thoughts despite having a finite set of words and rules. This is due, in part, to recursive structures, which allow us to embed one instance of a rule inside another. We investigated the origins of recursion by studying the development of Nicaraguan Sign Language (LSN), which emerged in the last 40 years and is not derived from any existing language. Before this, deaf individuals in Nicaragua lacked access to language models and each individual created their own gestural system, called homesign. We tested four groups: homesigners, who represent the point of origin, and the first three generations of LSN signers, who represent consecutive stages in the language's development. We used a task that was designed to elicit sentences with relative clauses, a device that allows for the recursive embedding of sentences inside of sentences (e.g., [the girl [who was drawing] removed the picture]). Signers in all three LSN cohorts consistently produced utterances that appeared to have embedded predicates (girl draw remove picture) which served the function of a relative clause (picking out the correct member of a set, based on previously mentioned information). Furthermore, in these utterances, the first verb was shorter than the second and shorter than the same verb in parallel unembedded structures. In contrast, homesigners produced similar utterances in embedded and unembedded contexts. They did not reintroduce previously mentioned information or produce reduced verb forms in the embedded context. These results demonstrate that syntactic embedding that is potentially recursive can emerge very early in a language. These embedded predicates, however, may not be widespread, or systematically marked, in homesign systems. This raises the possibility that the emergence of recursive linguistic structure is a consequence of interaction within a language community. These findings pave the way for future work which investigates the syntactic form of these embedded predicates and explores whether multiple levels of embedding are possible.

The Emergence of Natural Language Quantification.

Classical quantifiers (like "all," "some," and "none") express relationships between two sets, allowing us to make generalizations (like "no elephants fly"). Devices like these appear to be universal in human languages. Is the ubiquity of quantification due to a universal property of the human mind or is it attributable to more gradual convergence through cultural evolution? We investigated whether classical quantifiers are present in a new language emerging in isolation from other languages, Nicaraguan Sign Language (NSL). An observational study of historical data collected in the 1990s found evidence of potential quantifier forms. To confirm the quantificational meaning of these signs, we designed a production study that elicited, from three age cohorts of NSL signers (N = 17), three types of quantifiers: universal (all), existential (some), and negative (none). We find evidence for these classical quantifiers in the very first generation of signers, suggesting they may reflect a universal property of human cognition or a very rapid construction process.

The effects of maternal input on language in the absence of genetic confounds: Vocabulary development in internationally adopted children.

Previous studies have found correlations between parent input and child language outcomes, providing prima facie evidence for a causal relation. However, this could also reflect the effects of shared genes. The present study removed this genetic confound by measuring English vocabulary growth in 29 preschool-aged children (21 girls) aged 31-73 months and 17 infants (all girls) aged 15-32 months adopted from China and Eastern Europe and comparing it to speech produced by their adoptive mothers. Vocabulary growth in both groups was correlated with maternal input features; in infants with mean-length of maternal utterance, and in preschoolers with both mean-length of utterance and lexical diversity. Thus, input effects on language outcomes persist even in the absence of genetic confounds.

German-speaking children use sentence-initial case marking for predictive language processing at age four.

Adults incrementally integrate multiple sources of information to predict the upcoming linguistic structure. Although we have substantial evidence that children can use lexicosemantic information triggered by the verb, we have limited information as to whether children can use morphosyntax to generate predictions during the course of processing. Previous studies show that four-year-old Turkish-speaking children can use case-marking cues predictively; however German-speaking children have been reported to fail until late in development. The present visual-world eye-tracking study provides the first evidence from four-year-old German-speaking children (mean age: 4;03) interpreting sentence initial case marking cues independent of the identity of the verb and the canonical word order to predict the thematic role of the upcoming argument. We presented children with a visual context with a stereotypical but ambiguous event, the thematic structure of which can be resolved only on the basis of the case marking cues on subject-initial and object-initial structures locating the verb sentence-finally. Children were able to use the accusative case on the non-canonical object-initial utterances to predict that the upcoming argument should have the agent role before this argument and the verb became available. This study shows that the previously reported discrepancy between these two case-marking languages (i.e., Turkish and German) is not due to the crosslinguistic differences but due to methodological differences employed across studies. These findings provide support for language acquisition theories assuming early abstractions and adult-like parsing mechanisms predictively integrating multiple sources of cues.

Word vs. World Knowledge: A developmental shift from bottom-up lexical cues to top-down plausibility.

Both 5-year-old children and adults infer the structure of a sentence as they are hearing it. Prior work, however, has found that children do not always make use of the same information that adults do to guide these inferences. Specifically, when hearing ambiguous sentences like "You can tickle the frog with the feather," children seem to ignore the aspects of the referential context that adults rely on to resolve the ambiguity-e.g., are there two frogs in the scene, one with a feather and one without? Or is there only one frog to be tickled by using a feather? The present study explored two hypotheses about children's failure to use high-level, top-down context cues to infer the structure of these ambiguous sentences: First, children may be less likely to use any top-down cue during comprehension. Second, children may only have difficulties with top-down cues that are unreliable predictors of which syntactic structure is being used. Thus, to disentangle these hypotheses, we conducted a visual world study of adults' and children's ambiguity resolution, manipulating a more reliable top-down cue (the plausibility of the interpretation) and pitting it against a robust bottom-up cue (lexical biases). We find that adults' and children's final interpretations are influenced by both sources of information: adults, however, give greater weight to the top-down cue, whereas children primarily rely on the bottom-up cue. Thus, children's tendency to make minimal use of top-down information persists even when this information is highly valid and dominates adult comprehension. We propose that children have a systematic propensity to rely on bottom-up processing to a greater degree than adults, which could reflect differences in the architecture of the adult and child language comprehension systems or differences in processing speed.

Unexpected words or unexpected languages? Two ERP effects of code-switching in naturalistic discourse.

Bilingual speakers often switch between languages in conversation without any advance notice. Psycholinguistic research has found that these language shifts (or code-switches) can be costly for comprehenders in certain situations. The present study explores the nature of these costs by comparing code-switches to other types of unexpected linguistic material. To do this, we used a novel EEG paradigm, the Storytime task, in which we record readings of natural texts, and then experimentally manipulate their properties by splicing in words. In this study, we manipulated the language of our target words (English, Spanish) and their fit with the preceding context (strong-fit, weak-fit). If code-switching incurs a unique cost beyond that incurred by an unexpected word, then we should see an additive pattern in our ERP indices. If an effect is driven by lexical expectation alone, then there should be a non-additive interaction such that all unexpected forms incur a similar cost. We found three effects: a general prediction effect (a non-additive N400), a post-lexical recognition of the switch in languages (an LPC for code-switched words), and a prolonged integration difficulty associated with weak-fitting words regardless of language (a sustained negativity). We interpret these findings as suggesting that the processing difficulties experienced by bilinguals can largely be understood within more general frameworks for understanding language comprehension. Our findings are consistent with the broader literature demonstrating that bilinguals do not have two wholly separate language systems but rather a single language system capable of using two coding systems.

Evidence from the visual world paradigm raises questions about unaccusativity and growth curve analyses.

Many syntactic theories posit a fundamental structural difference between intransitive verbs with agentive subjects (unergative verbs) and those with theme subjects (unaccusative verbs). This claim garners support from studies finding differences in the online comprehension of these verbs. The present experiments seek to replicate one such finding using the visual world paradigm (Koring, Mak, & Reuland, 2012). We control for several factors that were uncontrolled in previous studies. We find no differences in the processing of unergative and unaccusative sentences in logistic regressions and cluster analyses. However, in growth curve analyses, modeled closely on the original paper, we find differences between the verb conditions that appear to be statistically significant but are unstable across experiments. A resampling analysis reveals that the growth curve analyses are highly anticonservative, suggesting that the earlier finding was a false positive. We conclude that there is no strong evidence that unaccusatives are processed differently from unergatives. We suggest that growth curve analyses only be used with visual world paradigm data when the underlying assumptions of the analysis can be validated via resampling.

How abstract is syntax? Evidence from structural priming.

In 1990, Bock and Loebell found that passives (e.g., The 747 was radioed by the airport's control tower) can be primed by intransitive locatives (e.g., The 747 was landing by the airport's control tower). This finding is often taken as strong evidence that structural priming occurs on the basis of a syntactic phrase structure that abstracts across lexical content, including prepositions, and is uninfluenced by the semantic roles of the arguments. However, all of the intransitive locative primes in Bock and Loebell contained the preposition by (by-locatives), just like the passive targets. Therefore, the locative-to-passive priming may have been due to the adjunct headed by by, rather than being a result of purely abstract syntax. The present experiment investigates this possibility. We find that passives and intransitive by-locatives are equivalent primes, but intransitive locatives with other prepositions (e.g., The 747 has landed near the airport control tower) do not prime passives. We conclude that a shared abstract, content-less tree structure is not sufficient for passive priming to occur. We then review the prior results that have been offered in favor of abstract tree priming, and note the range of evidence can be considerably narrowed-and possibly eliminated-once effects of animacy, semantic event structure, shared morphology, information structure, and rhythm are taken into account.

It takes a village: The role of community size in linguistic regularization.

Studies of artificial language learning provide insight into how learning biases and iterated learning may shape natural languages. Prior work has looked at how learners deal with unpredictable variation and how a language changes across multiple generations of learners. The present study combines these features, exploring how word order variation is preserved or regularized over generations. We investigate how these processes are affected by (1) learning biases, (2) the size of the language community, and (3) the amount of input provided. Our results show that when the input comes from a single speaker, adult learners frequency match, reproducing the variability in the input across three generations. However, when the same amount of input is distributed across multiple speakers, frequency matching breaks down. When regularization occurs, there is a strong bias for SOV word order (relative to OSV and VSO). Finally, when the amount of input provided by multiple speakers is increased, learners are able to frequency match. These results demonstrate that both population size and the amount of input per speaker each play a role in language convergence.

Children and adults successfully comprehend subject-only sentences online.

In many offline studies, children show selectively better comprehension of sentences with the focus particle only when it modifies the object argument (Jane only ate an apple) than they do when it modifies the subject argument (Only Jane ate an apple). Here we explore the nature of this asymmetry by examining performance in a different kind of task: the moment-to-moment comprehension of unambiguous sentences. If past errors reflect a fundamental difference in representation or complexity of computation, we would expect the same asymmetry in this task. We observed that adults were able to successfully predict the target referent for both types of only-sentences, as indicated by anticipatory looks, while 6- to 8-year-old children could do so only for subject-modifying only-sentences. These findings suggest that much of the asymmetry in past work may be due to task demands. We discuss the implications of these results for children's syntactic and pragmatic development.

Spared bottom-up but impaired top-down interactive effects during naturalistic language processing in schizophrenia: evidence from the visual-world paradigm.

BACKGROUND: People with schizophrenia process language in unusual ways, but the causes of these abnormalities are unclear. In particular, it has proven difficult to empirically disentangle explanations based on impairments in the top-down processing of higher level information from those based on the bottom-up processing of lower level information. METHODS: To distinguish these accounts, we used visual-world eye tracking, a paradigm that measures spoken language processing during real-world interactions. Participants listened to and then acted out syntactically ambiguous spoken instructions (e.g. 'tickle the frog with the feather', which could either specify how to tickle a frog, or which frog to tickle). We contrasted how 24 people with schizophrenia and 24 demographically matched controls used two types of lower level information (prosody and lexical representations) and two types of higher level information (pragmatic and discourse-level representations) to resolve the ambiguous meanings of these instructions. Eye tracking allowed us to assess how participants arrived at their interpretation in real time, while recordings of participants' actions measured how they ultimately interpreted the instructions. RESULTS: We found a striking dissociation in participants' eye movements: the two groups were similarly adept at using lower level information to immediately constrain their interpretations of the instructions, but only controls showed evidence of fast top-down use of higher level information. People with schizophrenia, nonetheless, did eventually reach the same interpretations as controls. CONCLUSIONS: These data suggest that language abnormalities in schizophrenia partially result from a failure to use higher level information in a top-down fashion, to constrain the interpretation of language as it unfolds in real time.

Why wait for the verb? Turkish speaking children use case markers for incremental language comprehension.

During language comprehension we must rapidly determine the thematic roles of arguments (who did what to whom) in order to semantically integrate the players into a single event and predict upcoming structure. While some languages signal these relations mostly with reliable word order, others rely more on case markers. The present study explores whether Turkish-speaking children use case marking predictively during online language comprehension. Specifically, we use the visual-world paradigm to test whether 4-year-olds (and adults) can use a contrast between nominative and accusative case on the first noun to predict the referent of the second noun in verb-medial and verb-final spoken sentences. In verb-medial sentences, both children and adults used case to predict the upcoming noun, but children did so only after hearing the verb. In verb-final structures, however, both children and adults made predictive looks to the correct referent prior to the second noun (and the verb). Thus, Turkish-speaking preschoolers interpret case marking incrementally, independent of the verb, and use it to anticipate the upcoming argument. These findings are inconsistent with the hypothesis that the online interpretation of case marking depends on a late maturing neural circuit. The predictive use of case at four provides strong evidence that children's comprehension relies on broad, abstract mappings between syntax and semantics, which allow children to determine the event role of a case marked argument prior to identifying the verb.

Event Structures Drive Semantic Structural Priming, Not Thematic Roles: Evidence From Idioms and Light Verbs.

What are the semantic representations that underlie language production? We use structural priming to distinguish between two competing theories. Thematic roles define semantic structure in terms of atomic units that specify event participants and are ordered with respect to each other through a hierarchy of roles. Event structures instead instantiate semantic structure as embedded sub-predicates that impose an order on verbal arguments based on their relative positioning in these embeddings. Across two experiments, we found that priming for datives depended on the degree of overlap in event structures. Specifically, while all dative structures showed priming, due to common syntax, there was a boost for compositional datives priming other compositional datives. Here, the two syntactic forms have distinct event structures. In contrast, there was no boost in priming for dative light verbs, where the two forms map onto a single event representation. On the thematic roles hypothesis, we would have expected a similar degree of priming for the two cases. Thus, our results support event structural approaches to semantic representation and not thematic roles.

How broad are thematic roles? Evidence from structural priming.

Verbs that are similar in meaning tend to occur in the same syntactic structures. For example, give and hand, which denote transfer of possession, both appear in the prepositional-object construction: "The child gave/handed the ball to the dog." We can call the child a "giver" in one case and a "hander" in the other, or we can refer to her more generally as the agent, or doer of the action. Similarly, the dog can be called the recipient, and the ball, the theme. These generalized notions of agent, recipient, and theme are known as thematic roles. An important theoretical question for linguists and psycholinguists is what the set of thematic roles is. Are there a small number of very broad roles, perhaps with each one mapping onto a single canonical syntactic position? Or are there many distinct roles, several mapping to the same syntactic position but conveying subtly different meanings? We investigate this question across eleven structural priming experiments on Amazon Mechanical Turk (total N = 2914), asking whether speakers treat the thematic roles recipient and destination (i.e., location or spatial goal) as interchangeable, suggesting the broad role of goal, or distinct, suggesting two separate roles. To do so, we look for priming between dative sentences (e.g., "The man gave the ball to the dog"), which have a recipient role (dog), and locative sentences (e.g., "The man loaded hay onto the wagon"), which instead have a destination role (wagon). Our pattern of findings confirms that thematic role mappings can be primed independent of syntactic structure, lexical content, and animacy. However, we find that this priming does not extend from destinations to recipients (or vice versa), providing evidence that these two roles are distinct.

Some inferences still take time: Prosody, predictability, and the speed of scalar implicatures.

Experimental pragmatics has gained many insights from understanding how people use weak scalar terms (like some) to infer that a stronger alternative (like all) is false. Early studies found that comprehenders initially interpret some without an upper bound, but later results suggest that this inference is sometimes immediate (e.g., Grodner, Klein, Carbary, & Tanenhaus, 2010). The present paper explores whether rapid inferencing depends on the prosody (i.e., summa rather than some of) or predictability of referring expressions (e.g., consistently using some to describe subsets). Eye-tracking experiments examined looks to subsets (2-of-4 socks) and total sets (3-of-3 soccer balls) following some and found early preferences for subsets in predictable contexts but not in less predictable contexts (Experiment 1 and 2). In contrast, there was no reliable prosody effect on inferencing. Changes in predictability did not affect judgments of the naturalness of some, when a discourse context was available (Experiment 3). However, predictable contexts reduced variability in speakers' descriptions of subsets and total sets (Experiment 4). Together, these results demonstrate that scalar inferences are often delayed during comprehension, but reference restriction is rapid when set descriptions can be formulated beforehand.

When Cars Hit Trucks and Girls Hug Boys: The Effect of Animacy on Word Order in Gestural Language Creation.

A well-known typological observation is the dominance of subject-initial word orders, SOV and SVO, across the world's languages. Recent findings from gestural language creation paradigms offer possible explanations for the prevalence of SOV. When asked to gesture transitive events with an animate agent and inanimate patient, gesturers tend to produce SOV order, regardless of their native language biases. Interestingly, when the patient is animate, gesturers shift away from SOV to use of other orders, like SVO and OSV. Two competing hypotheses have been proposed for this switch: the noisy channel account (Gibson et al., 2013) and the role conflict account (Hall, Mayberry, & Ferreira, 2013). We set out to distinguish between these two hypotheses, disentangling event reversibility and patient animacy, by looking at gestural sequences for events with two inanimate participants (inanimate-inanimate, reversible). We replicated the previous findings of a preference for SOV order when describing animate-inanimate, irreversible events as well as a decrease in the use of SOV when presented with animate-animate, reversible events. Accompanying the drop in SOV, in a novel condition we observed an increase in the use of SVO and OSV orders when describing events involving two animate entities. In sum, we find that the observed avoidance of SOV order in gestural language creation paradigms when the event includes an animate agent and patient is driven by the animacy of the participants rather than the reversibility of the event. We suggest that findings from gestural creation paradigms are not automatically linkable to spoken language typology.

Getting to No: Pragmatic and Semantic Factors in Two- and Three-Year-Olds' Understanding of Negation.

Although infants say "no" early, older children have difficulty understanding its truth-functional meaning. Two experiments investigate whether this difficulty stems from the infelicity of negative sentences out of the blue. In Experiment 1, given supportive discourse, 3-year-olds (N = 16) understood both affirmative and negative sentences. However, with sentence types randomized, 2-year-olds (N = 28) still failed. In Experiment 2, affirmative and negative sentences were blocked. Two-year-olds (N = 28) now succeeded, but only when affirmatives were presented first. Thus, although discourse felicity seems the primary bottleneck for 3-year-olds' understanding of negation, 2-year-olds struggle with its semantic processing. Contrary to accounts where negatives are understood via affirmatives, both sentence types were processed equally quickly, suggesting previously reported asymmetries are due to pragmatic accommodation, not semantic processing.