Cumulative input sensitivity predicts both attenuation and stability of lexically guided perceptual learning

Area of Science:

• Psycholinguistics
• Auditory Perception
• Speech Processing

Background:

• Lexical information aids listeners in resolving speech input ambiguity.
• Previous research shows conflicting evidence on the persistence of lexically guided perceptual learning over time.
• The belief-updating theory suggests continuous sensitivity to statistical cues in speech adaptation.

Purpose of the Study:

• To investigate the temporal dynamics of lexically guided perceptual learning.
• To reconcile conflicting findings regarding the persistence versus attenuation of this learning.
• To test the predictions of the belief-updating theory of speech adaptation.

Main Methods:

• 160 listeners were exposed to speech sounds ambiguous between /ʃ/ and /s/ in a lexical context.
• Listeners categorized tokens along an ashi-asi continuum during initial and delayed (24-hour) test phases.
• The duration of the initial test phase was manipulated (brief vs. long) to assess temporal effects.

Main Results:

• Lexically guided perceptual learning was evident at all time points.
• Learning attenuated with continued exposure during the test session.
• The duration of the initial test phase and the 24-hour delay did not significantly impact learning.

Conclusions:

• Lexically guided perceptual learning is an iterative process, reflecting continuous sensitivity to dynamic speech input.
• Learning attenuation is linked to exposure duration, not solely the passage of time.
• Findings support the belief-updating theory, unifying previous disparate results on speech adaptation.