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Eye Movements in Visual Duration Perception: Disentangling Stimulus from Time in Predecisional Processes
Published on: January 19, 2024
Visual discrimination of vowel duration
1Department of Behavioural Sciences and Learning, Linköping University, Sweden. bjorn.lidestam@liu.se
Scandinavian Journal of Psychology
|September 26, 2009
Summary
Listeners can discriminate vowel duration differences as small as 33 milliseconds. Errors in vowel duration perception were higher in visual tasks and for specific consonant contexts, showing a bias towards the first vowel.
Area of Science:
- Auditory perception research
- Speech science
- Psychoacoustics
Background:
- Vowel duration is a crucial phonetic cue in speech perception.
- Understanding the precise thresholds and biases in vowel duration discrimination is essential for speech processing models.
Purpose of the Study:
- To investigate vowel duration discrimination thresholds.
- To examine error biases and the influence of modality (visual, auditory, audiovisual) and consonant context on perception.
- To explore potential sublinguistic processing strategies.
Main Methods:
- 122 normal-hearing participants judged vowel length in disyllabic stimuli (/lal-lal/, /mam-mam/) with systematically varied vowel durations.
- Stimuli were presented visually, auditorily, or audiovisually across 24 steps (+/-33-400 ms).
- Just-noticeable differences (JNDs) and error patterns were analyzed.
Main Results:
- 50% JNDs were below 33 ms; 75% JNDs were typically 33-66 ms, except for /lal-lal/ (66-100 ms).
- Perceptual errors were highest in visual presentation and for /lal-lal/ stimuli.
- A bias towards perceiving the first vowel as longer was observed, particularly for /mam-mam/ and short vowels.
Conclusions:
- Normal-hearing listeners exhibit high sensitivity to vowel duration changes.
- Visual modality and certain consonant contexts (e.g., /lal/) increase discrimination difficulty and errors.
- An inherent bias towards the initial vowel may reflect early-stage speech processing mechanisms.
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