Helen L. Long

This study provides the first large-scale empirical evidence of infant vocal category clustering and exploration during the first year of life, showing non-random patterns in vocal production.

The paper quantifies the frequency of human infant laughter and protophones in natural environments, finding laughter occurs less frequently than cries and protophones dominate vocalizations.

This study examines the development of vocalization and gesture in infants, finding that vocalizations outpace gestures in frequency across early ages.

The paper examines canonical babbling in infants, finding higher ratios during periods of vocal turn taking and vocal play, suggesting both social and endogenous motivations influence vocal development.

The paper examines infant vocalizations, finding that most protophones are produced endogenously rather than directed at others, highlighting the infant's role in vocal learning.