Effects of delayed reinforcement on infant vocalization rate.
A 3-second wait before social praise still increases infant babbling, so BCBAs can safely use brief, natural delays in early-language interventions.
01Research in Context
What this study did
Four babies months visited a lab playroom with mom or dad. Each time the baby cooed or babbled, the parent smiled and said "good job" after a 3-second pause. The researchers flipped this on and off four times to be sure the praise was really driving the sounds.
What they found
Babbling doubled when the 3-second delayed praise was on. When parents stopped the praise, sounds dropped back to baseline. The simple pause did not kill the power of social reinforcement; it still worked.
How this fits with other research
Eisenmajer et al. (1998) saw the opposite: pigeons given the same 3-second unsignaled delay almost stopped pecking. The birds needed immediate food, but human infants can wait a few seconds for social attention.
Hansen et al. (1989) showed that young kids notice reinforcer size, not delay. The 1992 study adds real proof that babies will keep responding even when mom's smile is briefly held back.
Morris et al. (1982) used a 3-second pause before the child could answer, boosting correct choices in autistic learners. Together, these papers show a 3-second gap can help or hurt depending on where you place it and what the learner needs.
Why it matters
You do not have to deliver praise the instant a baby vocalizes. A short, natural pause while you finish a note or turn still keeps the social reward strong. Try counting "one-Mississippi, two-Mississippi, three-Mississippi" before your smile or tickle in early-language sessions; the delay is unlikely to weaken the skill and may even fit better with caregiver turn-taking.
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02At a glance
03Original abstract
Three previous studies have failed to demonstrate conditioning in infants using a 3-s delay of reinforcement. The effects of a delayed reinforcement schedule on vocalization rates therefore were explored in a single-subject repeated-reversal experimental design for 3 4- to 6-month-old normally developing infants. Each infant received delayed social reinforcement from his or her parent for vocalizing. The comparison condition was a schedule of differential reinforcement of behavior other than vocalizations to control for elicitation by social stimulation. An operant level of infant vocalizations was the initial condition, after which the differential reinforcement schedule was implemented in an across-subjects multiple baseline design. Infants' vocalization rates increased above levels measured during differential reinforcement following onset of the delayed reinforcement condition. Also, vocalization rates decreased during differential reinforcement compared to operant levels. The successful use of delayed reinforcement schedules with infants in this study, as opposed to others, is discussed in terms of procedural differences among them.
Journal of the experimental analysis of behavior, 1992 · doi:10.1901/jeab.1992.58-1