Speech categorization develops slowly through adolescence.

Area of Science:

• Cognitive Science
• Developmental Psychology
• Speech Perception

Background:

• Speech sound categorization is traditionally linked to infant perceptual learning.
• Research indicates speech categories continue to refine through childhood, up to age 12.
• Cognitive mechanisms underlying this protracted development remain underexplored.

Purpose of the Study:

• To investigate the cognitive changes driving speech category development beyond infancy.
• To examine how children's perception of speech sound continua evolves with age.

Main Methods:

• Utilized a visual world paradigm with auditory stimuli from /b/-/p/ and /s/-/ʃ/ continua.
• Monitored eye movements of children aged 7-8, 12-13, and 17-18 years in real-time.
• Assessed real-time lexical candidate commitment during speech perception.

Main Results:

• Demonstrated a continuous sharpening of phonetic categories in children up to 18 years old.
• Observed enhanced category sharpening during the initial phases of real-time speech perception.
• Found increasing sensitivity to within-category acoustic detail correlated with more discrete categories.

Conclusions:

• Speech sound categorization is a protracted developmental process extending into late adolescence.
• Increased sensitivity to fine-grained acoustic signals facilitates the development of sharper phonetic categories.
• Developmental changes in perceptual sensitivity underpin the refinement of speech categorization abilities.