Vowel Harmony as a cue for word order: Turkish adults

The present study aimed to investigate whether Turkish vowel harmony influences word-order preferences in native Turkish-speaking adults and whether it can reveal whether they process artificial-grammar test items at the morphological or syntactic level.The study adapted a word-order paradigm based on the frequency-based bootstrapping hypothesis by modifying the stimuli according to Turkish vowel harmony. In this paradigm, frequent items represent functor elements, while infrequent items represent content-word elements. Because Turkish is an object-verb and predominantly functor-final language, participants were expected to prefer infrequent–frequent (IF) sequences over frequent–infrequent (FI) sequences. Forty-five native Turkish adults completed the online experiment, making this the largest adult Turkish sample using this paradigm. The results showed that participants selected IF items significantly above chance, supporting the hypothesis that Turkish speakers show a preference for functor-final items. However, when the present data were compared with the Turkish data from Aydın and Gervain (2025), the IF preference did not differ significantly between the two studies. Thus, the findings did not provide evidence that vowel harmony strengthened participants’ IF preference. Nevertheless, the modified paradigm successfully elicited the expected IF preference. Because the IF items were harmonic only when segmented into separate word-like units, the findings were consistent with the hypothesis that participants processed them as syntactic sequences rather than as single words. Overall, the study used Turkish vowel harmony to examine both word-order preferences and the level at which artificial-grammar sequences are represented.