Eighteen-month-old infants represent nonlocal syntactic dependencies

Area of Science:

• Cognitive Science
• Developmental Psychology
• Linguistics

Background:

• Human language relies on syntax, a system for combining linguistic elements to create complex sentences.
• Syntax enables potentially unbounded dependencies over abstract structures, crucial for language expressiveness.
• The developmental trajectory of syntactic abilities, particularly abstract representations, remains an active area of research.

Purpose of the Study:

• To investigate whether infants can represent abstract nonlocal syntactic dependencies.
• To determine the age at which infants develop an awareness of complementary distribution patterns in syntax.
• To probe infants' underlying syntactic representations independently of semantic interpretation.

Main Methods:

• Utilized English wh-questions as a test case to examine nonlocal dependencies.
• Designed a novel test to assess infants' knowledge of argument structure constraints, specifically the complementary distribution of wh-phrases and local objects.
• Compared the performance of 18-month-old infants with younger infants on this syntactic representation task.

Main Results:

• 18-month-old infants demonstrated awareness of the complementary distribution pattern in wh-questions.
• Infants in this age group successfully represented the nonlocal grammatical dependency between the wh-phrase and the verb.
• Younger infants did not exhibit this understanding, indicating a developmental shift.

Conclusions:

• A core property of syntax, the ability to represent abstract nonlocal dependencies, emerges early in human development.
• The second year of life is a critical period for syntactic development, marked by the emergence of computational capacities for complex structures.
• Infants possess sophisticated syntactic knowledge even before mastering complex linguistic interpretations.