Recent publication on Nicaraguan Sign Language

Overview

This paper draws on over three decades of research on Lengua de Señas Nicaragüense (LSN) — one of the most studied cases of language emergence in the world — to identify the mechanisms that drive how sign languages form and change over time. Rather than focusing on a single linguistic feature, the authors synthesize findings from three separate studies to build a unified theoretical account of language emergence.

Key Concepts

The paper centers on two complementary processes that operate in tension as a language develops:

Emergence is the constructive process by which new linguistic forms and structures arise. For example, a pointing gesture that originally indicated physical location gradually took on the grammatical role of a pronoun in LSN — a new form-function mapping created through learner reanalysis.

Convergence is the reductive process by which competing forms are narrowed to a shared set across a community. For example, LSN signers progressively converged on two nonmanual markers — a brow furrow and head tilt — to accompany Wh-questions, paring down from six possible facial expressions used by the earliest cohort.

The Three Studies

Study 1 — Pointing and Deixis: Tracks how a locative pointing gesture was repurposed into a pronominal sign across successive cohorts of LSN signers. Homesigners and first-cohort signers showed little pronominal use of pointing; by the third cohort, it had become a stable grammatical feature.

Study 2 — Nonmanual Markers for Wh-Questions: Documents how six possible facial expressions used to mark Wh-questions by the first cohort narrowed to two dominant forms by the third cohort — an example of convergence driven by peer interaction and frequency of use.

Study 3 — Spatial Grammar and Argument Structure: Compares second-cohort deaf signers (who had extensive peer interaction) with hearing children of deaf adults (Codas, who lacked peer LSN interaction). Second-cohort signers uniformly adopted a contrastive spatial system for marking grammatical arguments; Codas showed much greater individual variation, demonstrating the critical role of horizontal peer interaction in convergence.

Core Findings

Vertical transmission — language passed from older, more experienced signers to younger learners — drives emergence. Learners reanalyze and restructure what they receive, introducing new grammatical connections. Horizontal interaction among peers drives convergence, aligning individual language systems toward shared conventions. Without peer interaction, as seen in both Codas and homesigners, convergence is weak and individual variation persists. Together, these two processes explain why sign languages around the world, despite independent origins, tend to share many structural properties.

Significance

This research contributes to a broader understanding of how all human languages evolve. The Nicaraguan deaf community provides a rare natural experiment: a living language young enough to observe rapid change across generations, yet complex enough to reveal deep patterns in how grammar emerges. The findings suggest that the typological similarities observed across unrelated sign languages are not coincidental — they are the predictable product of how humans acquire and transmit language.