Final answer:
The back-and-forth vocalizations between a mother and her baby that lead to recognized words are known as successive approximation, a concept in behaviorism where behaviors are gradually shaped toward a target through reinforcement.
Step-by-step explanation:
The process you're describing, where a baby makes a sound and a mother responds, guiding the infant's vocalizations toward recognizable words, is known as successive approximation. Successive approximation is a behaviorist concept where actions are rewarded progressively as they come closer and closer to a desired behavior. This process is part of how infants learn to speak; it begins with cooing and babbling, and eventually leads to the formation of actual words. Through interaction and reinforcement from parents and caregivers, babies begin to understand and replicate the sounds and words from their native language(s). The involvement of gesture usage predicting subsequent language development and the notion of both nature (innate abilities) and nurture (environmental factors) playing a role underscore the complexity of language acquisition.