Accessing lexical ambiguities during sentence comprehension: Effects of frequency of meaning and contextual bias

Two hypotheses concerning the nature of lexical access, the exhaustive access and the terminating ordered search hypotheses, were examined in two separate studies using a crossmodal lexical priming task. In this task, subjects listened to sentences that were biased toward either the primary interpretation (a meaning occurring 75% or more of the time) or a secondary interpretation (a meaning occurring less than 25% of the time) of a lexical ambiguity that occurred in each sentence. Simultaneously, subjects made lexical decisions about visually presented words. Decisions to words related to both the primary and secondary meanings of the ambiguity were facilitated when presented immediately following occurrence of the ambiguity in the sentence. This effect held under each of the two biasing context conditions. However, when they were presented 1.5 sec following occurrence of the ambiguity, only visual words related to the contextually relevant meaning of the ambiguity were facilitated. These results support the exhaustive access hypothesis. It is argued that lexical access is an autonomous subsystem of the sentence comprehension routine in which all meanings of a word are momentarily accessed, regardless of the factors of contextual bias or bias associated with frequency of use.     

They call it like they see it: spontaneous naming and attention to shape

Two experiments explore children's spontaneous labeling of novel objects as a method to study early lexical access. The experiments also provide new evidence on children's attention to object shape when labeling objects. In Experiment 1, the spontaneous productions of 21 23- to 28-month-olds (mean 26;28) shown a set of novel, unnamed objects were analyzed both in terms of the specific words said and, via adult judgments, their likely perceptual basis. We found that children's spontaneous names were cued by the perceptual feature of shape. Experiment 2 examines the relation between spontaneous productions, name generalizations in a structured task, and vocabulary development in a group of children between 17 and 24 months of age (mean 21;6). Results indicate that object shape plays an important role in both spontaneous productions and novel noun generalization, but contrary to current hypotheses, children may name objects by shape from the earliest points of productive vocabulary development and this tendency may not be lexically specific.     

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 a model with caregiver total 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.

Research Highlights

• We examined the frequency of referential communicative behaviors, via labels and/or gestures, produced by caregivers during a 5-min play interaction with their 18-month-old children.
• We assessed predictive relations between labels, gestures, their combination, as well as total words spoken, and children's processing speed and vocabulary growth at 25 months.
• Bayesian model comparisons showed that caregivers’ referential labels at 18 months best predicted both 25-month vocabulary measures, although total words also predicted later processing speed.
• Frequent use of referential labels by caregivers, more so than referential gestures, is a critical feature of communicative behavior that supports children's later vocabulary learning.

     

Propose but verify: Fast mapping meets cross-situational word learning

We report three eyetracking experiments that examine the learning procedure used by adults as they pair novel words and visually presented referents over a sequence of referentially ambiguous trials. Successful learning under such conditions has been argued to be the product of a learning procedure in which participants provisionally pair each novel word with several possible referents and use a statistical-associative learning mechanism to gradually converge on a single mapping across learning instances [e.g., Yu, C., & Smith, L. B. (2007). Rapid word learning under uncertainty via cross-situational statistics. Psychological Science, 18(5), 414–420]. We argue here that successful learning in this setting is instead the product of a one-trial procedure in which a single hypothesized word-referent pairing is retained across learning instances, abandoned only if the subsequent instance fails to confirm the pairing – more a ‘fast mapping’ procedure than a gradual statistical one. We provide experimental evidence for this propose-but-verify learning procedure via three experiments in which adult participants attempted to learn the meanings of nonce words cross-situationally under varying degrees of referential uncertainty. The findings, using both explicit (referent selection) and implicit (eye movement) measures, show that even in these artificial learning contexts, which are far simpler than those encountered by a language learner in a natural environment, participants do not retain multiple meaning hypotheses across learning instances. As we discuss, these findings challenge ‘gradualist’ accounts of word learning and are consistent with the known rapid course of vocabulary learning in a first language.     

Looking for Wugs in all the Right Places: Children's Use of Prepositions in Word Learning

To help infer the meanings of novel words, children frequently capitalize on their current linguistic knowledge to constrain the hypothesis space. Children's syntactic knowledge of function words has been shown to be especially useful in helping to infer the meanings of novel words, with most previous research focusing on how children use preceding determiners and pronouns/auxiliary to infer whether a novel word refers to an entity or an action, respectively. In the current visual world experiment, we examined whether 28- to 32-month-olds could exploit their lexical semantic knowledge of an additional class of function words—prepositions—to learn novel nouns. During the experiment, children were tested on their ability to use the prepositions in, on, under, and next to to identify novel creatures displayed on a screen (e.g., The wug is on the table), as well as their ability to later identify the creature without accompanying prepositions (e.g., Look at the wug). Children overall demonstrated understanding of all the prepositions but next to and were able to use their knowledge of prepositions to learn the associations between novel words and their intended referents, as shown by greater-than chance looks to the target referent when no prepositional phrase was provided.     

Disentangling the effects of cognitive development and linguistic expertise: a longitudinal study of the acquisition of English in internationally-adopted children

Early language development is characterized by predictable changes in the words children produce and the complexity of their utterances. In infants, these changes could reflect increasing linguistic expertise or cognitive maturation and development. To disentangle these factors, we compared the acquisition of English in internationally-adopted preschoolers and internationally-adopted infants. Parental reports and speech samples were collected for 1 year. Both groups showed the qualitative shifts that characterize first-language acquisition. Initially, they produced single-word utterances consisting mostly of nouns and social words. The appearance of verbs, adjectives and multiword utterances was predicted by vocabulary size in both groups. Preschoolers did learn some words at an earlier stage than infants, specifically words referring to the past or future and adjectives describing behavior and internal states. These findings suggest that cognitive development plays little role in the shift from referential terms to predicates but may constrain children's ability to learn some abstract words.     

Adjectives really do modify nouns: the incremental and restricted nature of early adjective acquisition

By 24 months, most children spontaneously and correctly use adjectives. Yet prior laboratory research that has studied lexical acquisition in young children reports that children up to 3-years-old map novel adjectives to object properties only in very limited situations (Child Development 59 (1988) 411; Child Development 64 (1993) 1651; Child Development 71 (2000) 649; Developmental Psychology 36 (2000) 571; Child Development 69 (1998) 1313). In Experiments 1 and 2 we introduced 36-month-olds (Experiment 1) and 24-month-olds (Experiment 2) to novel adjectives while providing rich referential and syntactic information to indicate what the novel words mean. Specifically, we used a given novel adjective to describe multiple familiar objects which shared a salient property; in addition we used the adjectives in full noun phrases, not in conjunction with pronouns. Under these conditions, both groups mapped novel adjectives onto object properties. In Experiment 3 we asked whether the rich referential information was responsible for the successful outcome of the previous two experiments; we introduced novel adjectives to 2- and 3-year-olds as in Experiments 1 and 2, but the adjectives modified nouns of vague (very general) reference ("one", or "thing"). Under these conditions the children failed. We suggest that young word learners require access to the taxonomy of the object type so that the relevant property can be identified. The taxonomically specific nouns of Experiments 1 and 2 accomplish this, whereas the more general, semantically bleached nominals in Experiment 3 do not. Taken together with related findings in the literature, these findings favor an account of lexical acquisition in which layers of information become available incrementally, as a consequence of solving prior parts of the learning problem.     

Is this a dax which I see before me? Use of the logical argument disjunctive syllogism supports word-learning in children and adults

Many authors have argued that word-learning constraints help guide a word-learner's hypotheses as to the meaning of a newly heard word. One such class of constraints derives from the observation that word-learners of all ages prefer to map novel labels to novel objects in situations of referential ambiguity. In this paper I use eye-tracking to document the mental computations that support this word-learning strategy. Adults and preschoolers saw images of known and novel objects, and were asked to find the referent of known and novel labels. Experiment 1 shows that adults systematically reject a known distractor (e.g. brush) before mapping a novel label (e.g. "dax") to a novel object. This is consistent with the proposal that participants worked through a Disjunctive Syllogism (i.e. Process-of-Elimination) to motivate the mapping of the novel label to the novel object. Experiment 2 shows that processing is similar for adults performing an implicit Disjunctive Syllogism (e.g. "the winner is the dax") and an explicit Disjunctive Syllogism (e.g. "the winner is not the iron"). Experiment 3 reveals that similar processes govern preschoolers' mapping of novel labels. Taken together, these results suggest that word-learners use Disjunctive Syllogism to motivate the mapping of novel labels to novel objects.     

Young children's use of prosody in sentence parsing

Korean children's ability to use prosodic phrasing in sentence comprehension was studied using two types of ambiguity. First, we examined a word-segmentation ambiguity in which placement of the phrasal boundary leads to different interpretations of a sentence. Next, we examined a syntactic ambiguity in which the same words were differently grouped into syntactic phrases by prosodic demarcation. Children aged 3 or 4 years showed that they could use prosodic information to segment utterances and to derive the meaning of ambiguous sentences when the sentences only contained a word-segmentation ambiguity. However, even 5- to 6-year-old children were not able to reliably resolve the second type of ambiguity, an ambiguity of phrasal grouping, by using prosodic information. The results demonstrate that children's difficulties in dealing with structural ambiguity are not due to their inability to use prosodic information.     

Ontological categories and function: Acquisition of new names

This study asks whether knowledge of the functional properties of a referent for a new name influences children's first guesses about whether that name refers to an object or a substance. Recent work on children's categorization suggests that children differentiate concrete objects from nonsolid substances and that their initial hypotheses about the meanings of new words are affected by this knowledge of ontological categories. In addition, some research has suggested that children approach new words with a set of biases that constrain the possible meanings of those words. Most of this work has presented children with new names in the absence of explicit information about the functional characteristics of new referents. Our hypothesis was that if children are shown the functional properties of referents, they should use that information in making their first guesses about the meanings of new words. Seventy-two 3- and 4-year-olds were shown new items with new names and were tested on their extension of each new name either to a similarly shaped item made of a different material or to a differently shaped item made of the same material. Some subjects were shown a “shape-linked” function, some a “substance-linked” function, and some no function at all. One third of the subjects heard the new names presented with count syntax, one third with mass syntax, and one third with neutral syntax. Results suggest that children do not rely on a single source of information in extending new names, but, rather, draw on various kinds of information, including the perceptual characteristics of the entities themselves and the syntax of the input.     

The properties of retrieval cues constrain the picture superiority effect

In three experiments, we examined why pictures are remembered better than words on explicit memory tests like recall and recognition, whereas words produce more priming than pictures on some implicit tests, such as word-fragment and word-stem completion (e.g., completing -l-ph-nt or ele----- as elephant). One possibility is that pictures are always more accessible than words if subjects are given explicit retrieval instructions. An alternative possibility is that the properties of the retrieval cues themselves constrain the retrieval processes engaged; word fragments might induce data-driven (perceptually based) retrieval, which favors words regardless of the retrieval instructions. Experiment 1 demonstrated that words were remembered better than pictures on both the word-fragment and word-stem completion tasks under both implicit and explicit retrieval conditions. In Experiment 2, pictures were recalled better than words with semantically related extralist cues. In Experiment 3, when semantic cues were combined with word fragments, pictures and words were recalled equally well under explicit retrieval conditions, but words were superior to pictures under implicit instructions. Thus, the inherently data-limited properties of fragmented words limit their use in accessing conceptual codes. Overall, the results indicate that retrieval operations are largely determined by properties of the retrieval cues under both implicit and explicit retrieval conditions.     

Social cues modulate the representations underlying cross-situational learning

Because children hear language in environments that contain many things to talk about, learning the meaning of even the simplest word requires making inferences under uncertainty. A cross-situational statistical learner can aggregate across naming events to form stable word-referent mappings, but this approach neglects an important source of information that can reduce referential uncertainty: social cues from speakers (e.g., eye gaze). In four large-scale experiments with adults, we tested the effects of varying referential uncertainty in cross-situational word learning using social cues. Social cues shifted learners away from tracking multiple hypotheses and towards storing only a single hypothesis (Experiments 1 and 2). In addition, learners were sensitive to graded changes in the strength of a social cue, and when it became less reliable, they were more likely to store multiple hypotheses (Experiment 3). Finally, learners stored fewer word-referent mappings in the presence of a social cue even when given the opportunity to visually inspect the objects for the same amount of time (Experiment 4). Taken together, our data suggest that the representations underlying cross-situational word learning of concrete object labels are quite flexible: In conditions of greater uncertainty, learners store a broader range of information.     

Individual differences in the linguistic competence of referential and expressive subjects

The aim of this work was to examine individual differences in referential and expressive style through a longitudinal study. The composition of the first 50 words, communicative gestures, the conversational style of dyads and the percentage of vocabulary produced from 12 to 24 month-olds were analyzed. The vocabulary was collected through interviews to parents and sessions of mother-infant interaction in the laboratory. Significant differences in the proportion of common nouns and frozen phrases between referential and expressive children in the frequency of communicative gestures and style conversation were found. Thus, referential children and their mothers used more pointing gestures than the expressive children and their mothers. Additionally, mothers of referential children used completing more frequently.     

"Shhh! We're tryin' to concentrate": attention and environmental distracters in novel word learning

The authors' purpose in this study was to evaluate the role of attention, as a central dimension of temperament, in children's real-time acquisition of novel vocabulary. Environmental distractions were administered to 47 22-month-old children as they acquired novel vocabulary in a fast-mapping task. Two distraction conditions impeded novel word acquisition, but only 1 impeded attention allocation. Attention allocation was correlated with novel word acquisition under conditions of distraction, but not in their absence. Results suggest that attention allocation is especially important for word learning under conditions of distraction. Given that in their day-to-day lives children often encounter new words amid a host of environmental distractions, children with constitutionally fewer attentional resources, such as temperamentally difficult children, may be at a vocabulary-learning disadvantage.     

The kindergarten path effect revisited: children's use of context in processing structural ambiguities

Research with adults has shown that ambiguous spoken sentences are resolved efficiently, exploiting multiple cues--including referential context--to select the intended meaning. Paradoxically, children appear to be insensitive to referential cues when resolving ambiguous sentences, relying instead on statistical properties intrinsic to the language such as verb biases. The possibility that children's insensitivity to referential context may be an artifact of the experimental design used in previous work was explored with 60 4- to 11-year-olds. An act-out task was designed to discourage children from making incorrect pragmatic inferences and to prevent premature and ballistic responses by enforcing delayed actions. Performance on this task was compared directly with the standard act-out task used in previous studies. The results suggest that young children (5 years) do not use contextual information, even under conditions designed to maximize their use of such cues, but that adult-like processing is evident by approximately 8 years of age. These results support and extend previous findings by Trueswell and colleagues (Cognition (1999), Vol. 73, pp. 89-134) and are consistent with a constraint-based learning account of children's linguistic development.     

Preschoolers use speakers’ preferences to learn words

In two studies, we investigated preschoolers’ ability to use others’ preferences to learn names for things. Two studies demonstrated that preschool children make smart use of others’ preferences. In the first study, preschool children only used information about others’ preferences when they were clearly linked to referential intentions. The second study established that children only used others’ preferences to learn words when the preference and intention information came from the same person. Both studies reveal impressive use of mental state information for word learning purposes.     

WORD EXPOSURE CONDITIONS AND PRESCHOOLERS' NOVEL WORD LEARNING DURING SHARED STORYBOOK READING

In this experiment, 23 preschool children participated in two adult-child shared storybook reading sessions over a 1-week period. The objective was to characterize the influence of various conditions of word exposure upon children's receptive and expressive learning of novel words occurring within storybook reading interactions. Specifically, the effects of two contrasting conditions were examined: (a) adults' questioning versus labeling of novel words, and (b) adults' use of perceptual versus conceptual questions about novel words. Results suggested that adults' labeling of novel words facilitated children's receptive word learning more so than questioning; however, this effect was not observed for expressive word learning. Results also suggested no difference in receptive or expressive word learning as a result of conceptual versus perceptual questions. Implications of these findings are discussed.     

Preschoolers' perspective taking in word learning: do they blindly follow eye gaze?

When learning new words, do children use a speaker's eye gaze because it reveals referential intent? We conducted two experiments that addressed this question. In Experiment 1, the experimenter left while two novel objects were placed where the child could see both, but the experimenter would be able to see only one. The experimenter returned, looked directly at the mutually visible object, and said either, "There's the [novel word]!" or "Where's the [novel word]?" Two- through 4-year-olds selected the target of the speaker's gaze more often on there trials than on where trials, although only the older children identified the referent correctly at above-chance levels on trials of both types. In Experiment 2, the experimenter placed a novel object where only the child could see it and left while the second object was similarly hidden. When she returned and asked, "Where's the [novel word]?" 2- through 4-year-olds chose the second object at above-chance levels. Preschoolers do not blindly follow gaze, but consider the linguistic and pragmatic context when learning a new word.     

Pragmatics aid referent disambiguation and word learning in young children and adults

How do children succeed in learning a word? Research has shown robustly that, in ambiguous labeling situations, young children assume novel labels to refer to unfamiliar rather than familiar objects. However, ongoing debates center on the underlying mechanism: Is this behavior based on lexical constraints, guided by pragmatic reasoning, or simply driven by children's attraction to novelty? Additionally, recent research has questioned whether children's disambiguation leads to long-term learning or rather indicates an attentional shift in the moment of the conversation. Thus, we conducted a pre-registered online study with 2- and 3-year-olds and adults. Participants were presented with unknown objects as potential referents for a novel word. Across conditions, we manipulated whether the only difference between both objects was their relative novelty to the participant or whether, in addition, participants were provided with pragmatic information that indicated which object the speaker referred to. We tested participants’ immediate referent selection and their retention after 5 min. Results revealed that when given common ground information both age groups inferred the correct referent with high success and enhanced behavioral certainty. Without this information, object novelty alone did not guide their selection. After 5 min, adults remembered their previous selections above chance in both conditions, while children only showed reliable learning in the pragmatic condition. The pattern of results indicates how pragmatics may aid referent disambiguation and learning in both adults and young children. From early ontogeny on, children's social-cognitive understanding may guide their communicative interactions and support their language acquisition.

Research Highlights

• We tested how 2-3-year-olds and adults resolve referential ambiguity without any lexical cues.
• In the pragmatic context both age groups disambiguated novel word-object-mappings, while object novelty alone did not guide their referent selection.
• In the pragmatic context, children also showed increased certainty in disambiguation and retained new word-object-mappings over time.
• These findings contribute to the ongoing debate on whether children learn words on the basis of domain-specific constraints, lower-level associative mechanisms, or pragmatic inferences.