Forging a morphological system out of two dimensions: Agentivity and number

Area of Science:

• Linguistics
• Developmental Psychology
• Cognitive Science

Background:

• Languages exhibit diverse strategies for encoding grammatical information like agentivity and number.
• The emergence and negotiation of these strategies into combinatorial systems are not fully understood.
• Sign languages offer a unique window into language acquisition and evolution, particularly in early stages.

Purpose of the Study:

• To investigate the emergence of strategies for marking agentivity and number in Nicaraguan Sign Language (NSL).
• To compare the gestural and signing systems of different groups, including early and later NSL learners, homesigners, established sign languages, and silent gesture.
• To understand the role of action experience and linguistic community in the development of grammatical marking.

Main Methods:

• Comparative analysis of movement features (axis, repetition) in agentivity and number marking.
• Study involved two cohorts of Nicaraguan Sign Language (NSL1 and NSL2) learners.
• Included adult homesigners, users of American Sign Language (ASL) and Italian Sign Language (LIS), and hearing individuals performing silent gestures.

Main Results:

• All groups utilize movement axis and repetition for agentivity and number, indicating a grounding in shared action experiences.
• Unpunctuated repetition, a feature of sign systems (ASL, LIS, NSL, Homesign), was absent in silent gesture.
• Homesigners and NSL1 signers restricted unpunctuated repetition to 'No-Agent' contexts; NSL2 signers generalized its use to both 'Agent' and 'No-Agent' contexts.

Conclusions:

• Individuals can develop basic grammatical markers like number from action experience alone (homesign).
• Generalizing these markers across different agentive conditions requires more than individual innovation; it necessitates community transmission.
• The expansion of unpunctuated repetition use in NSL2 suggests that grammatical generalization occurs across generations of language learners.