Much research has found disrupted executive functioning (EF) in deaf and hard-of-hearing (DHH) children; while some theories emphasize the role of auditory deprivation, others posit delayed language experience as the primary cause. This study investigated the role of language and auditory experience in parent-reported EF for 123 preschool-aged children (M_age = 60.1 months, 53.7% female, 84.6% White). Comparisons between DHH and typically hearing children exposed to language from birth (spoken or signed) showed no significant differences in EF despite drastic differences in auditory input. Linear models demonstrated that earlier language exposure predicted better EF (β = .061–.341), while earlier auditory exposure did not. Few participants exhibited clinically significant executive dysfunction. Results support theories positing that language, not auditory experience, scaffolds EF development.

It is largely acknowledged that natural languages emerge not just from human brains but also from rich communities of interacting human brains (Senghas, 2005). Yet the precise role of such communities and such interaction in the emergence of core properties of language has largely gone uninvestigated in naturally emerging systems, leaving the few existing computational investigations of this issue at an artificial setting. Here, we take a step toward investigating the precise role of community structure in the emergence of linguistic conventions with both naturalistic empirical data and computational modeling. We first show conventionalization of lexicons in two different classes of naturally emerging signed systems: (a) protolinguistic “homesigns” invented by linguistically isolated Deaf individuals, and (b) a natural sign language emerging in a recently formed rich Deaf community. We find that the latter conventionalized faster than the former. Second, we model conventionalization as a population of interacting individuals who adjust their probability of sign use in response to other individuals' actual sign use, following an independently motivated model of language learning (Yang, 2002, 2004). Simulations suggest that a richer social network, like that of natural (signed) languages, conventionalizes faster than a sparser social network, like that of homesign systems. We discuss our behavioral and computational results in light of other work on language emergence, and other work of behavior on complex networks.

Many sign languages display crosslinguistic consistencies in the use of two iconic aspects of handshape, handshape type and finger group complexity. Handshape type is used systematically in form-meaning pairings (morphology): Handling handshapes (Handling-HSs), representing how objects are handled, express events with an agent (“hand-as-hand” iconicity), and Object handshapes (Object-HSs), representing an object's size/shape, are used to express events without an agent (“hand-as-object” iconicity). Second, in the distribution of meaningless properties of form (morphophonology), Object-HSs display higher finger group complexity than Handling-HSs. Some adult homesigners, who have not acquired spoken or signed language and instead use a self-generated gesture system, exhibit these two properties as well. We examined both structures over time in one child homesigner, “Julio”, age 7;4 (years; months) to 12;8. We elicited descriptions of events with and without agents to determine whether morphophonology and morphosyntax can develop without linguistic input during childhood, and their relative timing. Within this period: 1) Julio used handshapes differently in his responses to vignettes with and without an agent; however, his pattern differed from that seen in signers, adult homesigners, or gesturers: while he tended to use a Handling-HS for events with an agent (82%), he was less likely to use an Object-HS for non-agentive events (49%); 2) his Object-HSs showed higher finger group complexity than his Handling-HSs, as in previously studied signers and adult homesigners; and 3) these two levels of structure developed independently, with phonological structure showing a sign-like pattern at an earlier age than morphosyntactic structure. We conclude that iconicity alone is insufficient to explain the development of linguistic contrasts in homesign. These findings also highlight the importance of considering the distribution of forms within an emerging linguistic system.