Turkish-German heritage speakers' predictive use of case: webcam-based vs. in-lab eye-tracking

Area of Science:

• Linguistics
• Psychology

Background:

• Heritage speakers (HSs) acquire a heritage language at home and a majority societal language, which often becomes dominant.
• Turkish HSs show greater variability in case-marking comprehension and production compared to monolinguals.
• Previous research suggests monolingual children can interpret case-marking predictively, disregarding word order.

Purpose of the Study:

• To compare in-lab and remote webcam-based eye-tracking data collection for elicitation.
• To test the replicability of in-lab eye-tracking effects using webcam-based methods.
• To investigate predictive case-marking in Turkish monolinguals and HSs.

Main Methods:

• Direct comparison of in-lab and webcam-based eye-tracking data collection.
• Analysis of data from 22 Turkish monolinguals and 27 HSs using binomial generalized linear mixed-effects regression.
• Examination of participants' eye movements in Accusative and Nominative conditions.

Main Results:

• Monolinguals and HSs looked for the suitable Agent (Accusative) or Patient (Nominative) before it appeared in speech.
• HSs demonstrated the ability to use morphosyntactic cues on NP1 to predict the thematic role of NP2.
• Webcam-based eye-tracking successfully replicated predictive case use in monolinguals but not in HSs due to data variability.

Conclusions:

• Core grammatical features like case remain robust in HSs, supporting the Interface Hypothesis.
• Individual variation exists in HSs' predictive use of case marking, influenced by various factors.
• A native-speaker continuum model is proposed to explain variability in HS language outcomes.