Sudha Arunachalam

Information content versus relational knowledge: Semantic deficits in patients with Alzheimer's disease

Studies of semantic impairment in Alzheimers disease (AD) have yielded conflicting results, some finding evidence of considerable deficits, others finding that semantic knowledge is relatively intact. How do we reconcile findings from picture naming tasks that seem to indicate semantic impairment in AD with results from certain sorting tasks that suggest intact semantics? To investigate the basis of the contradictory results described above, we conducted a study using two types of tasks: (1) picture naming; and (2) board sorting. The board sorting task we used is a simultaneous similarity judgment task, in which participants are asked to place more similar concepts closer together and less similar ones farther apart. We compared the performance of AD patients on these two tasks, using a number of different analyses that yield very different patterns of results. Our results indicate that whether patients show impairment or not depends on both the nature of the task and the subsequent analysis chosen. Specifically, tasks and analyses that focus on relational knowledge (e.g., dog is more related to cat than to camel) lead to different conclusions than those based on specific information about individual items. These findings suggest that the board sorting method, when coupled with multiple analyses, provides a more complete picture of the underlying semantic deficit in AD than previous studies have shown.

Out of sight, but not out of mind: 21-month-olds use syntactic information to learn verbs even in the absence of a corresponding event

By 27 months of age, toddlers hearing a novel verb in transitive syntax are able to (1) establish an initial representation for the verb based on its syntactic properties alone, even in the absence of a relevant visual scene, and (2) retrieve this representation later when a candidate causative referent comes into view. This ability is important considering that over 60% of the verbs that mothers produce in conversations with their children refer to events that are not currently observable. Here, we advance this finding in two ways. First, we demonstrate the same ability in 21-month-olds, who do not yet show mastery of transitive structures in their own productions. Second, we use analyses of toddlers’ eye gaze to explore the time-course with which they process the novel verb and assign its referent when candidate scenes become available. These results (1) provide the first evidence that 21-month-olds establish a representation of a novel verbs meaning from syntax alone, and (2) establish that they process and assign meaning to novel verbs with a similar time-course to that for novel nouns. The findings are thus relevant to our understanding of both word learning and lexical processing of novel words.

Doing More With Less: Verb Learning in Korean-Acquiring 24-Month-Olds

Research on early word learning reveals that verbs present a unique challenge. While English-acquiring 24-month-olds can learn novel verbs and extend them to new scenes, they perform better in rich linguistic contexts (when novel verbs appear with lexicalized noun phrases naming the event participants) than in sparser linguistic contexts (Arunachalam & Waxman 2011) However, in languages like Korean, where noun phrases are often omitted when their referents are highly accessible, rich linguistic contexts are less frequent. The current study investigates the influence of rich and sparse linguistic contexts in verb learning in Korean-acquiring 24-month-olds. In contrast to their English-acquiring counterparts, 24-month-olds acquiring Korean perform better when novel verbs appear in sparse linguistic contexts. These results, which provide the first experimental evidence on early verb learning in Korean, indicate that the optimal context for verb learning depends on many factors, including how event participants are typically referred to in the language being acquired.

Two-year-olds can begin to acquire verb meanings in socially impoverished contexts.

By two years of age, toddlers are adept at recruiting social, observational, and linguistic cues to discover the meanings of words. Here, we ask how they fare in impoverished contexts in which linguistic cues are provided, but no social or visual information is available. Novel verbs are presented in a stream of syntactically informative sentences, but the sentences are not embedded in a social context, and no visual access to the verbs referent is provided until the test phase. The results provide insight into how toddlers may benefit from overhearing contexts in which they are not directly attending to the ambient speech, and in which no conversational context, visual referent, or child-directed conversation is available.

The integrity of lexical acquisition mechanisms in autism spectrum disorders: A research review.

Research on autism spectrum disorders (ASD) has rapidly expanded in recent years, yielding important developments in both theory and practice. While we have gained important insights into how children with ASD differ from typically developing (TD) children in terms of phenotypic features, less has been learned about if and how development in ASD differs from typical development in terms of underlying mechanisms of change. This article aims to provide a review of processes subserving lexical development in ASD, with the goal of identifying contributing factors to the heterogeneity of language outcomes in ASD. The focus is on available evidence of the integrity or disruption of these mechanisms in ASD, as well as their significance for vocabulary development; topics include early speech perception and preference, speech segmentation, word learning, and category formation. Significant gaps in the literature are identified and future directions are suggested. Autism Res 2016, 9: 810–828.

Let’s See a Boy and a Balloon: Argument Labels and Syntactic Frame in Verb Learning

It is by now well established that toddlers use the linguistic context in which a new word—and particularly a new verb—appears to discover aspects of its meaning. But what aspects of the linguistic context are most useful? To begin to investigate this, we ask how 2-year-olds use two sources of linguistic information that are known to be useful to older children and adults in verb guessing tasks: syntactic frame and the semantic content available in the noun phrases labeling the verb’s arguments. We manipulate the linguistic contexts in which we present novel verbs to see how they use these two sources of information, both separately and in combination, to acquire the verb’s meaning. Our results reveal that, like older children and adults, toddlers make use of both syntactic frame and semantically contentful argument labels to acquire verb meaning. But toddlers also require these two sources of information to be packaged in a particular way, into a single sentence that identifies “who did what to whom.”

Slowly but Surely: Adverbs Support Verb Learning in 2-Year-Olds

To acquire the meanings of verbs, toddlers make use of the surrounding linguistic information. For example, 2-year-olds successfully acquire novel transitive verbs that appear in semantically rich frames containing content nouns (“The boy is gonna pilk a balloon”), but they have difficulty with pronominal frames (“He is gonna pilk it”) (Arunachalam & Waxman, 2010). We hypothesized that adverbs might facilitate toddlers’ verb learning in these sparse pronominal frames if their semantic content directed toddlers’ attention to aspects of the event that are relevant to the verb’s meaning (e.g., the manner of motion). As predicted, the semantic information from a specific manner-of-motion adverb (slowly) supported verb learning, but other adverbs lacking this semantic content (nicely, right now) did not. These results provide the first evidence that adverbs can facilitate verb learning in toddlers and highlight the interaction of syntactic and semantic information in word learning.

Eye-Tracking Measurements of Language Processing: Developmental Differences in Children at High Risk for ASD

To explore how being at high risk for autism spectrum disorder (ASD), based on having an older sibling diagnosed with ASD, affects word comprehension and language processing speed, 18-, 24- and 36-month-old children, at high and low risk for ASD were tested in a cross- sectional study, on an eye gaze measure of receptive language that measured how accurately and rapidly the children looked at named target images. There were no significant differences between the high risk ASD group and the low risk control group of 18- and 24-month-olds. However, 36-month-olds in the high risk for ASD group performed significantly worse on the accuracy measure, but not on the speed measure. We propose that the language processing efficiency of the high risk group is not compromised, but other vocabulary acquisition factors might have lead to the high risk 36-month-olds to comprehend significantly fewer nouns on our measure.

Acquisition of Verb Meaning From Syntactic Distribution in Preschoolers With Autism Spectrum Disorder

Purpose Our goal was to investigate whether preschool children with autism spectrum disorder (ASD) can begin to learn new word meanings by attending to the linguistic contexts in which they occur, even in the absence of visual or social context. We focused on verbs because of their importance for subsequent language development. Method Thirty-two children with ASD, ages 2;1-4;5 (years;months), participated in a verb-learning task. In a between-subjects design, they were randomly assigned to hear novel verbs in either transitive or intransitive syntactic frames while watching an unrelated silent animation or playing quietly with a toy. In an eye-tracking test, they viewed two video scenes, one depicting a causative event (e.g., boy spinning girl) and the other depicting synchronous events (e.g., boy and girl waving). They were prompted to find the referents of the novel verbs, and their eye gaze was measured. Results Like typically developing children in prior work, children with ASD who had heard the verbs in transitive syntactic frames preferred to look to the causative scene as compared to children who had heard intransitive frames. Conclusions This finding replicates and extends prior work on verb learning in children with ASD by demonstrating that they can attend to a novel verbs syntactic distribution absent relevant visual or social context, and they can use this information to assign the novel verb an appropriate meaning. We discuss points for future research, including examining individual differences that may impact success and contrasting social and nonsocial word-learning tasks directly.

Lexical Disambiguation in Verb Learning: Evidence from the Conjoined-Subject Intransitive Frame in English and Mandarin Chinese

When presented with a novel verb in a transitive frame (X is Ving Y), young children typically select a causative event referent, rather than one in which agents engage in parallel, non-causative synchronous events. However, when presented with a conjoined-subject intransitive frame (X and Y are Ving), participants (even adults, as we show) are at chance. Although in some instances, children older than three can obtain above-chance-level performance, these experiments still appear to rely upon a within-experiment contrast with the transitive frame. This leads us to ask whether children can achieve success with the intransitive frame without such a contrast among constructions, and map a novel verb appearing in such a frame onto a non-causative meaning. Building on recent evidence that adverbial modifiers can support word learning for adjectives and for verbs (when both nominal and verbal candidate interpretations are considered) by directing children to a particular construal of a scene, we test the hypothesis that a semantically informative modifier, together, will provide children with additional lexical information that allows them to narrow down verb meaning and identify a non-causative interpretation for a novel verb appearing in the conjoined-subject intransitive frame. We find that for English-speaking children and adults it does, but only when together directly modifies the verb phrase, suggesting that participants appeal to compositionality and not just the brute addition of another word, even one that is semantically meaningful, to arrive at the intended interpretation. Children acquiring Mandarin Chinese, in contrast, do not succeed with the translation-equivalent of together (although adult speakers do), but they do with dōu (roughly, the distributive quantifier “each”). Our results point to a valuable source of information young children learning verbs: modifiers with familiar semantics.