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Article published In: Journal of Second Language Pronunciation
Vol. 11:2 (2025) ► pp.240–266

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Linguistic dimensions of comprehensibility and perceived fluency in L2 speech across tasks of varying complexity

ORCiD logo with link | Institute of Science Tokyo
ORCiD logo with link | Institute of Science Tokyo
Published online: 13 May 2025
DOI logo with link
https://doi.org/10.1075/jslp.24057.lu
Abstract
This study investigated the effects of task complexity on the linguistic dimensions of comprehensibility and perceived fluency in L2 Japanese. 36 Chinese-speaking learners of Japanese performed two argumentative speech tasks with differing levels of complexity. These audio samples were judged by eight experienced native raters of Japanese for comprehensibility and perceived fluency and then analyzed in terms of complexity, accuracy, and fluency. The results showed that linguistic correlates of comprehensibility exhibit a task-specific effect, with additional linguistic dimensions (e.g., syntactic density, explicit grammatical marking) becoming increasingly relevant as task complexity rises. In contrast, perceived fluency also undergoes a task-specific shift but differently: rather than expanding the set of predictors, it changes the nature of primary cues, placing greater emphasis on syntactic sophistication alongside (but not replacing) temporal aspects. Findings underscore the unique role of Japanese linguistic system in shaping listeners’ judgments of L2 Japanese.
Article outline
  • 1.Introduction
  • 2.Literature review
    • 2.1Relationship between comprehensibility and fluency
    • 2.2Linguistic dimensions of comprehensibility and perceived fluency
      • 2.2.1Comprehensibility
      • 2.2.2Perceived fluency
      • 2.2.3Function words and listeners’ judgments in L2 Japanese
    • 2.3Task effects
      • 2.3.1Task complexity manipulation
      • 2.3.2Validation of task complexity manipulation
    • 2.4Research questions
  • 3.Method
    • 3.1Participants
      • 3.1.1Speakers
      • 3.1.2Raters
    • 3.2Speech materials
    • 3.3Secondary task
    • 3.4Self-assessment of perceived task difficulty and mental effort
    • 3.5Procedure
    • 3.6Rating procedure
    • 3.7Data coding
      • Complexity
        • Syntactic complexity
        • Lexical complexity
      • Accuracy
      • Fluency
        • Speed fluency
        • Breakdown fluency
        • Repair fluency
    • 3.8Statistical analysis
  • 4.Results
    • 4.1Validation of cognitive task complexity manipulation
    • 4.2Interrater reliability
    • 4.3Relationship between comprehensibility and perceived fluency
    • 4.4Linguistic dimensions of comprehensibility
      • 4.4.1Comprehensibility model in low-complexity task
      • 4.4.2Comprehensibility model in high-complexity task
    • 4.5Linguistic dimension of perceived fluency
      • 4.5.1Perceived fluency model in low-complexity task
      • 4.5.2Perceived fluency model in high-complexity task
  • 5.Discussion
    • 5.1RQ1: Relationship between comprehensibility and perceived fluency
    • 5.2RQ2: Linguistic correlates of comprehensibility across task complexity
    • 5.3RQ3: Linguistic correlates of perceived fluency across task complexity
  • 6.Conclusion
  • References
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Cited by (1)

Cited by one other publication

Lu, Jialiang & Reiko Sato
2025. Effects of Domain, Modality, and Linguistic Complexity on Cognitive Load and Self-Efficacy in Learning Academic Content in L2. IEEE Access 13 ► pp. 162436 ff. DOI logo

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