Emergent Morphology in Child Homesign: Evidence from Number Language.

Human languages, signed and spoken, can be characterized by the structural patterns they use to associate communicative forms with meanings. One such pattern is paradigmatic morphology, where complex words are built from the systematic use and re-use of sub-lexical units. Here, we provide evidence of emergent paradigmatic morphology akin to number inflection in a communication system developed without input from a conventional language, homesign. We study the communication systems of four deaf child homesigners (mean age 8;02). Although these idiosyncratic systems vary from one another, we nevertheless find that all four children use handshape and movement devices productively to express cardinal and non-cardinal number information, and that their number expressions are consistent in both form and meaning. Our study shows, for the first time, that all four homesigners not only incorporate number devices into representational devices used as predicates , but also into gestures functioning as nominals, including deictic gestures. In other words, the homesigners express number by systematically combining and re-combining additive markers for number (qua inflectional morphemes) with representational and deictic gestures (qua bases). The creation of new, complex forms with predictable meanings across gesture types and linguistic functions constitutes evidence for an inflectional morphological paradigm in homesign and expands our understanding of the structural patterns of language that are, and are not, dependent on linguistic input.

The Problematic Concept of Native Speaker in Psycholinguistics: Replacing Vague and Harmful Terminology With Inclusive and Accurate Measures.

Though the term NATIVE SPEAKER/SIGNER is frequently used in language research, it is inconsistently conceptualized. Factors, such as age, order, and context of acquisition, in addition to social/cultural identity, are often differentially conflated. While the ambiguity and harmful consequences of the term NATIVE SPEAKER have been problematized across disciplines, much of this literature attempts to repurpose the term in order to include and/or exclude certain populations. This paper problematizes NATIVE SPEAKER within psycholinguistics, arguing that the term is both unhelpful to rigorous theory construction and harmful to marginalized populations by reproducing normative assumptions about behavior, experience, and identity. We propose that language researchers avoid NATIVE SPEAKER altogether, and we suggest alternate ways of characterizing language experience/use. The vagueness of NATIVE SPEAKER can create problems in research design (e.g., through systematically excluding certain populations), recruitment (as participants' definitions might diverge from researchers'), and analysis (by distilling continuous factors into under-specified binary categories). This can result in barriers to cross-study comparison, which is particularly concerning for theory construction and replicability. From a research ethics perspective, it matters how participants are characterized and included: Excluding participants based on binary/essentialist conceptualizations of nativeness upholds deficit perspectives toward multilingualism and non-hegemonic modes of language acquisition. Finally, by implicitly assuming the existence of a critical period, NATIVE SPEAKER brings with it theoretical baggage which not all researchers may want to carry. Given the issues above and how 'nativeness' is racialized (particularly in European and North American contexts), we ask that researchers consider carefully whether exclusion of marginalized/minoritized populations is necessary or justified-particularly when NATIVE SPEAKER is used only as a way to achieve linguistic homogeneity. Instead, we urge psycholinguists to explicitly state the specific axes traditionally implied by NATIVENESS that they wish to target. We outline several of these (e.g., order of acquisition, allegiance, and comfort with providing intuitions) and give examples of how to recruit and describe participants while eschewing NATIVE SPEAKER. Shifting away from harmful conventions, such as NATIVE SPEAKER, will not only improve research design and analysis, but also is one way we can co-create a more just and inclusive field.

The resilience of structure built around the predicate: Homesign gesture systems in Turkish and American deaf children.

Deaf children whose hearing losses prevent them from accessing spoken language and whose hearing parents have not exposed them to sign language develop gesture systems, called homesigns, that have many of the properties of natural language-the so-called resilient properties of language. We explored the resilience of structure built around the predicate-in particular, how manner and path are mapped onto the verb-in homesign systems developed by deaf children in Turkey and the United States. We also asked whether the Turkish homesigners exhibit sentence-level structures previously identified as resilient in American and Chinese homesigners. We found that the Turkish and American deaf children used not only the same production probability and ordering patterns to indicate who does what to whom, but also the same segmentation and conflation patterns to package manner and path. The gestures that the hearing parents produced did not, for the most part, display the patterns found in the children's gestures. Although co-speech gesture may provide the building blocks for homesign, it does not provide the blueprint for these resilient properties of language.