Characterizing the Dynamics of Learning in Repeated Reference Games

The language we use over the course of conversation changes as we establish common ground and learn what our partner finds meaningful. Here we draw upon recent advances in natural language processing to provide a finer-grained characterization of the dynamics of this learning process. We release an open corpus (>15,000 utterances) of extended dyadic interactions in a classic repeated reference game task where pairs of participants had to coordinate on how to refer to initially difficult-to-describe tangram stimuli. We find that different pairs discover a wide variety of idiosyncratic but efficient and stable solutions to the problem of reference. Furthermore, these conventions are shaped by the communicative context: words that are more discriminative in the initial context (i.e., that are used for one target more than others) are more likely to persist through the final repetition. Finally, we find systematic structure in how a speaker's referring expressions become more efficient over time: Syntactic units drop out in clusters following positive feedback from the listener, eventually leaving short labels containing open-class parts of speech. These findings provide a higher resolution look at the quantitative dynamics of ad hoc convention formation and support further development of computational models of learning in communication.     

Acquisition of the Meaning of the Word Orange Requires Understanding of the Meanings of Red,Pink, and Purple: Constructing a Lexicon as a Connected System

This research investigated how children build up the language-specific system of the color lexicon, examining factors that play important roles for the construction of an adult-like color lexicon. We had 3-, 4-, and 5-year-old Japanese-speaking children and adults (n = 20, 18, 19, and 19, respectively) produce names for 93 color swatches. The results showed that children of all ages were able to apply most of the chromatic words to the colors close to the center of each category, but even 5-year-olds struggle to delineate the boundaries between the words. Furthermore, the model analyses revealed that broad-covering and high-frequency words are mapped to the center of the lexical category earlier. However, cross-individual consistency in adults' use contributed most strongly for the adult-like boundary delineation. The results suggest that the process of system construction consists of at least two steps (i.e., mapping words to their category center and finding appropriate boundaries between neighboring words), with the quantity and the quality of the input contributing differently to the steps.     

Comparison Types in the Semantic Extension of Diidxazá Body Part Terms

Body part terms (BPTs) are used extensively in Mesoamerican languages to name object parts. The process through which BPTs might be extended to refer to a part of an object and further serve as a relator in describing the relation between objects in space has often been attributed to metaphorical processes. This study proposes an alternative analysis following a Structure–Mapping Theory approach (Gentner, 1983, inter alia), based on data from Diidxazá (Isthmus Zapotec, Otomanguean) obtained through elicitation and experimental tasks. The data show that structure mapping does not depend on a 1:1 match of attributes; frequency of use shed light on principles that constrain the semantic extension of most BPTs; a core set of six BPTs are extended by abstraction of the set of intersecting axes of the body. The detailed nature of this study enables an analysis of the mental representations underlying the semantic extension of BPTs. This in turn elucidates on aspects of the relation between spatial language and spatial cognition. In addition, this study allows us to address questions about the categorial status of BPTs in Diidxazá and their lexicographic representation.     

Russian-language neurosemantics: Clustering of word meaning and sense from oral narratives

This article is a part of a large-scale brain mapping project aimed at finding the relations among semantic categories in oral Russian-language texts and brain activity as measured using functional magnetic resonance imaging (fMRI). The goal of present study in particular is to examine the nature of lexical semantic relations and find an appropriate lexical space, homeomorphic to the activation patterns in the brain. Participants were presented with oral narratives, which described significant social issues from the first-person perspective. Stimuli were annotated using a dictionary and a vector approach. Results show that fMRI signal and clusters of related words have similar patterns of brain activation across participants. Results also show that annotation by a list of features more strongly contributes to prediction of the observed activation patterns. Findings confirm the hypothesis of situational semantic representation in the brain.     

Musical structure modulates semantic priming in vocal music

It has been shown that harmonic structure may influence the processing of phonemes whatever the extent of participants' musical expertise [Bigand, E., Tillmann, B., Poulin, B., D'Adamo, D. A., & Madurell, F. (2001). The effect of harmonic context on phoneme monitoring in vocal music. Cognition, 81, B11-B20]. The present study goes a step further by investigating how musical harmony may potentially interfere with the processing of words in vocal music. Eight-chord sung sentences were presented, their last word being either semantically related (La girafe a un tres grand cou, The giraffe has a very long neck) or unrelated to the previous linguistic context (La girafe a un tres grand pied, The giraffe has a very long foot). The target word was sung on a chord that acted either as a referential tonic chord or as a congruent but less referential subdominant chord. Participants performed a lexical decision task on the target word. A significant interaction was observed between semantic and harmonic relatedness suggesting that music modulates semantic priming in vocal music. Following Jones' dynamic attention theory, we argue that music can modulate semantic priming in vocal music, by modifying the allocation of attentional resource necessary for linguistic computation.     

Brain oscillations during semantic evaluation of speech

Changes in oscillatory brain activity have been related to perceptual and cognitive processes such as selective attention and memory matching. Here we examined brain oscillations, measured with electroencephalography (EEG), during a semantic speech processing task that required both lexically mediated memory matching and selective attention. Participants listened to nouns spoken in male and female voices, and detected an animate target (p = 20%) in a train of inanimate standards or vice versa. For a control task, subjects listened to the same words and detected a target male voice in standards of a female voice or vice versa. The standard trials of the semantic task showed enhanced upper beta (25–30 Hz) and gamma band (GBA, 30–60 Hz) activity compared to the voice task. Upper beta and GBA enhancement was accompanied by a suppression of alpha (8–12 Hz) and lower to mid beta (13–20 Hz) activity mainly localized to posterior electrodes. Enhancement of phase-locked theta activity peaking near 275 ms also occurred over the midline electrodes. Theta, upper beta, and gamma band enhancement may reflect lexically mediated template matching in auditory memory, whereas the alpha and beta suppression likely indicate increased attentional processes and memory demands.     

Electrophysiology reveals semantic memory use in language comprehension

The physical energy that we refer to as a word, whether in isolation or embedded in sentences, takes its meaning from the knowledge stored in our brains through a lifetime of experience. Much empirical evidence indicates that, although this knowledge can be used fairly flexibly, it is functionally organized in ‘semantic memory’ along a number of dimensions, including similarity and association. Here, we review recent findings using an electrophysiological brain component, the N400, that reveal the nature and timing of semantic memory use during language comprehension. These findings show that the organization of semantic memory has an inherent impact on sentence processing. The left hemisphere, in particular, seems to capitalize on the organization of semantic memory to pre-activate the meaning of forthcoming words, even if this strategy fails at times. In addition, these electrophysiological results support a view of memory in which world knowledge is distributed across multiple, plastic-yet-structured, largely modality-specific processing areas, and in which meaning is an emergent, temporally extended process, influenced by experience, context, and the nature of the brain itself.     

Think globally: cross-linguistic variation in electrophysiological activity during sentence comprehension

This paper demonstrates systematic cross-linguistic differences in the electrophysiological correlates of conflicts between form and meaning (“semantic reversal anomalies”). These engender P600 effects in English and Dutch (e.g. [Kolk et al., 2003] and [Kuperberg et al., 2003]), but a biphasic N400 - late positivity pattern in German (Schlesewsky and Bornkessel-Schlesewsky, 2009), and monophasic N400 effects in Turkish (Experiment 1) and Mandarin Chinese (Experiment 2). Experiment 3 revealed that, in Icelandic, semantic reversal anomalies show the English pattern with verbs requiring a position-based identification of argument roles, but the German pattern with verbs requiring a case-based identification of argument roles. The overall pattern of results reveals two separate dimensions of cross-linguistic variation: (i) the presence vs. absence of an N400, which we attribute to cross-linguistic differences with regard to the sequence-dependence of the form-to-meaning mapping and (ii) the presence vs. absence of a late positivity, which we interpret as an instance of a categorisation-related late P300, and which is observable when the language under consideration allows for a binary well-formedness categorisation of reversal anomalies. We conclude that, rather than reflecting linguistic domains such as syntax and semantics, the late positivity vs. N400 distinction is better understood in terms of the strategies that serve to optimise the form-to-meaning mapping in a given language.     

Semantic dementia and persisting Wernicke's aphasia: linguistic and anatomical profiles

Few studies have directly compared the clinical and anatomical characteristics of patients with progressive aphasia to those of patients with aphasia caused by stroke. In the current study we examined fluent forms of aphasia in these two groups, specifically semantic dementia (SD) and persisting Wernicke’s aphasia (WA) due to stroke. We compared 10 patients with SD to 10 age- and education-matched patients with WA in three language domains: language comprehension (single words and sentences), spontaneous speech and visual semantics. Neuroanatomical involvement was analyzed using disease-specific image analysis techniques: voxel-based morphometry (VBM) for patients with SD and overlays of lesion digitized lesion reconstructions in patients with WA. Patients with SD and WA were both impaired on tasks that involved visual semantics, but patients with SD were less impaired in spontaneous speech and sentence comprehension. The anatomical findings showed that different regions were most affected in the two disorders: the left anterior temporal lobe in SD and the left posterior middle temporal gyrus in chronic WA. This study highlights that the two syndromes classically associated with language comprehension deficits in aphasia due to stroke and neurodegenerative disease are clinically distinct, most likely due to distinct distributions of damage in the temporal lobe.