Infant Vocal Behavior During Contingent Vocal Imitation and Its Interruption as a Window Into the Emerging Sense of Agency.
Five-month-olds instantly ramp up cooing when adults echo them, proving they already grasp that their voice drives social feedback.
01Research in Context
What this study did
Researchers watched 5- to 6-month-old babies during short play sessions.
When a baby cooed, the adult copied the sound right away.
After a few minutes the adult stopped copying to see what happened.
Each baby served as their own control in this single-case design.
What they found
Babies doubled or tripled their sounds as soon as the adult imitated them.
When imitation stopped, vocal output stayed high; it did not drop.
The quick jump shows infants notice their sounds make adults reply.
How this fits with other research
Kremkow et al. (2022) saw the opposite pattern in babies with Rett syndrome.
Those infants made fewer clear babbles than typical peers at 9–11 months.
The difference is not a clash; Diprossimo studied healthy 5-month-olds while D et al. tracked a disorder where vocal loss is expected.
Espanola Aguirre et al. (2019) later showed typical toddlers learn vocal imitation in the same step-wise order, so this early sensitivity may feed that hierarchy.
Why it matters
You now have a fast probe to check if an infant senses social contingencies.
No toys, no tables—just echo the baby’s sounds for one minute and count.
If vocal rate jumps, the child detects their own agency; if not, flag for follow-up.
Use this screener before referring for possible developmental delay.
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02At a glance
03Original abstract
Infants' emerging sense of agency is thought to be supported by caregivers' contingent responsiveness. However, it remains unclear which types of responses are most relevant to this process. Here, we examined the role of contingent vocal imitation, defined as the prompt repetition of an infant's vocalization by an interaction partner. To tease apart the contribution of contingent vocal imitation from other elements of social interactions, we developed a novel vocal contingency paradigm. First, we investigated whether 5‐ to 6‐month‐old infants could rapidly learn the contingency between their own vocalizing and a novel imitative response. Then, we examined whether infants tested this newly learned contingency when it was suddenly discontinued. Novel audio‐visual imitative responses were delivered and manipulated by an artificial agent. Infants' vocalizations were recorded while they experienced the novel contingency (connect phase) and its discontinuation (disconnect phase). Time‐course analyses indicated a significant linear increase in vocalization frequency over time in the connect phase, supporting the hypothesis that contingent vocal imitation enables rapid vocal contingency learning. Descriptively, data suggested a quadratic trend consistent with a vocal extinction burst during the disconnect phase. However, this trend did not reach statistical significance. Therefore, there was only partial support for the role of contingent vocal imitation in the emerging sense of agency (i.e., young infants quickly learned this contingency, but there was no evidence that they tested it upon discontinuation). Overall, our paradigm provided proof of concept that vocal contingency learning can be studied in the absence of a human interaction partner.
Infancy, 2026 · doi:10.1111/infa.70080