Erica A. Cartmill

Quality of early parent input predicts child vocabulary 3 years later

Children vary greatly in the number of words they know when they enter school, a major factor influencing subsequent school and workplace success. This variability is partially explained by the differential quantity of parental speech to preschoolers. However, the contexts in which young learners hear new words are also likely to vary in referential transparency; that is, in how clearly word meaning can be inferred from the immediate extralinguistic context, an aspect of input quality. To examine this aspect, we asked 218 adult participants to guess 50 parents’ words from (muted) videos of their interactions with their 14- to 18-mo-old children. We found systematic differences in how easily individual parents’ words could be identified purely from this socio-visual context. Differences in this kind of input quality correlated with the size of the children’s vocabulary 3 y later, even after controlling for differences in input quantity. Although input quantity differed as a function of socioeconomic status, input quality (as here measured) did not, suggesting that the quality of nonverbal cues to word meaning that parents offer to their children is an individual matter, widely distributed across the population of parents.

Ontogenetic Ritualization of Primate Gesture as a Case Study in Dyadic Brain Modeling

This paper introduces dyadic brain modeling – the simultaneous, computational modeling of the brains of two interacting agents – to explore ways in which our understanding of macaque brain circuitry can ground new models of brain mechanisms involved in ape interaction. Specifically, we assess a range of data on gestural communication of great apes as the basis for developing an account of the interactions of two primates engaged in ontogenetic ritualization, a proposed learning mechanism through which a functional action may become a communicative gesture over repeated interactions between two individuals (the ‘dyad’). The integration of behavioral, neural, and computational data in dyadic (or, more generally, social) brain modeling has broad application to comparative and evolutionary questions, particularly for the evolutionary origins of cognition and language in the human lineage. We relate this work to the neuroinformatics challenges of integrating and sharing data to support collaboration between primatologists, neuroscientists and modelers that will help speed the emergence of what may be called comparative neuro-primatology.

Great ape gestures: intentional communication with a rich set of innate signals

Great apes give gestures deliberately and voluntarily, in order to influence particular target audiences, whose direction of attention they take into account when choosing which type of gesture to use. These facts make the study of ape gesture directly relevant to understanding the evolutionary precursors of human language; here we present an assessment of ape gesture from that perspective, focusing on the work of the “St Andrews Group” of researchers. Intended meanings of ape gestures are relatively few and simple. As with human words, ape gestures often have several distinct meanings, which are effectively disambiguated by behavioural context. Compared to the signalling of most other animals, great ape gestural repertoires are large. Because of this, and the relatively small number of intended meanings they achieve, ape gestures are redundant, with extensive overlaps in meaning. The great majority of gestures are innate, in the sense that the species’ biological inheritance includes the potential to develop each gestural form and use it for a specific range of purposes. Moreover, the phylogenetic origin of many gestures is relatively old, since gestures are extensively shared between different genera in the great ape family. Acquisition of an adult repertoire is a process of first exploring the innate species potential for many gestures and then gradual restriction to a final (active) repertoire that is much smaller. No evidence of syntactic structure has yet been detected.

Mind the Gap Assessing and Addressing the Word Gap in Early Education

Children from poor families typically know fewer words when they enter school than children from wealthy families do. This “word gap” persists over time and may significantly affect educational achievement. The language children hear at home before they start school influences how many words they learn. Children from poorer families typically hear fewer words. New programs tackle the language gap by encouraging poorer parents to talk more to their children. These programs have excellent intentions, but they also have significant limitations. They count only the number of words, ignoring important differences in how language is used in social and physical contexts. They also carry implicit ideologies about “correct” language practices and may stigmatize some parents or cultures. To succeed in leveling the playing field in early education, interventions should consider features of language beyond the word and partner more closely with parents to create sustainable programs tailored to the desires and practices of local communities.

The development of iconicity in children’s co-speech gesture and homesign

Gesture can illustrate objects and events in the world by iconically reproducing elements of those objects and events. Children do not begin to express ideas iconically, however, until after they have begun to use conventional forms. In this paper, we investigate how childrens use of iconic resources in gesture relates to the developing structure of their communicative systems. Using longitudinal video corpora, we compare the emergence of manual iconicity in hearing children who are learning a spoken language (co-speech gesture) to the emergence of manual iconicity in a deaf child who is creating a manual system of communication (homesign). We focus on one particular element of iconic gesture - the shape of the hand (handshape). We ask how handshape is used as an iconic resource in 1-5-year-olds, and how it relates to the semantic content of childrens communicative acts. We find that patterns of handshape development are broadly similar between co-speech gesture and homesign, suggesting that the building blocks underlying childrens ability to iconically map manual forms to meaning are shared across different communicative systems: those where gesture is produced alongside speech, and those where gesture is the primary mode of communication.

IS PANTOMIME A LIKELY STAGE IN LANGUAGE EVOLUTION? EVIDENCE FROM HUMAN AND PRIMATE GESTURE

Gestural origin of language theories (e.g. Corballis, 2002; Armstrong & Wilcox, 2007) have garnered increasing interest, fueled by studies of great ape gestural communication and primate mirror neurons. Gesture, particularly pantomime, has been suggested as a key stage of hominid communication before the codification of a shared symbolic system (Arbib, 2005). Pantomime is an attractive candidate because it can be understood without a conventional system and allows sharing of novel or absent events through iconic representation. Arbib (2005) proposes that increased imitation abilities in the human lineage (driven by hierarchical processing of action sequences) provided the foundation for iconic representation of action through gesture. This became the beginnings of pantomime. His proposal leads one to ask: what are the challenges in developing a pantomime-based system, and how early could this stage occur? To this end, we discuss acquisition and use of iconicity in human and ape gesture and point out difficulties in developing an iconic system. Iconic gesture is a powerful communicative and cognitive tool because it can represent objects and events outside of real-world acts. However, iconic gesture is a complex task even for modern humans, and involves a level of symbolic understanding beyond imitation. Pantomime-like gestures involving manipulation of imaginary objects are complex, and young children struggle with them (Overton & Jackson, 1973). Children do not use iconic gestures until near age three, well after they have acquired conventional gestures that rely on shared meanings. Furthermore, young children do not map iconic gestures to referents more quickly than conventional gestures, indicating that iconicity in gesture does not aid early stages of language learning (Namy et al., 2004). The relationship between language learning and language evolution must be

EVOLUTION OF TENSE AND ASPECT

One cognitive domain that may have influenced, and perhaps even shaped, the evolution of language is mental time travel the ability to mentally relive events in the past (episodic memory) or imagine events in the future. Language structure has evolved to express different points in time, including past, present and future, and to make other temporal distinctions, such as action completed versus action ongoing. We examine the activation of Broca’s and Wernicke’s area in the evolution of tense and aspect of English using near-infrared spectroscopy. We demonstrate that the activation of the core brain system used in remembering the past and imagining the future induced the evolution of tense and aspect, which do not present themselves as separate categories and are interwoven in grammatical systems in that one and the same grammatical form may combine temporal and aspectual elements. After categorization of the periphrastic constructions of progressive and perfective, and auxiliaries to denote future tense, aspect is specialized to the left hemisphere, and the distinction of the forms between present, past and future tense caused less activation of the core networks of the brain. Here we can see the interaction between brain and language.