Infant-directed speech reduces English-learning infants' preference for trochaic words

Area of Science:

• Child language acquisition
• Developmental psychology
• Speech and hearing sciences

Background:

• Infant-directed speech (IDS) is known to aid speech, language, and cognitive development.
• Infants possess sensitivity to the rhythmic structures within their ambient language.
• The specific role of IDS in infants' processing of linguistic rhythmic structures remains underexplored.

Purpose of the Study:

• To investigate whether infant-directed speech (IDS) enhances infants' sensitivity to the predominant English stress pattern, known as the trochaic pattern.
• To compare infants' processing of trochaic and iambic words in both IDS and adult-directed speech (ADS).

Main Methods:

• Nine-month-old American infants participated in the study.
• Familiarization and testing phases involved presenting trochaic (e.g., "lazy") and iambic (e.g., "cartoon") words.
• Speech stimuli were delivered in either infant-directed speech (IDS) or adult-directed speech (ADS).

Main Results:

• Infants demonstrated a listening preference for trochaic over iambic words when speech was presented in adult-directed speech (ADS).
• This preference for trochaic stress patterns was not observed when speech was presented in infant-directed speech (IDS).
• Acoustical analyses revealed that IDS contained less salient spectral cues for syllable stress contrasts in trochaic words compared to ADS.

Conclusions:

• Infant-directed speech (IDS) appears to attenuate, or reduce, infants' natural preference for the trochaic stress pattern in English.
• The acoustic properties of IDS may play a role in this observed effect, offering weaker cues for stress contrasts.
• These findings suggest a need for broader exploration into how IDS influences various aspects of language acquisition.