Narrowing the gap: effects of intervention on developmental trajectories in autism.
EIBI bends the developmental curve upward, especially when kids start young, receive high intensity, and show higher baseline skills.
01Research in Context
What this study did
Klintwall et al. (2015) tracked kids with autism who got Early Intensive Behavioral Intervention.
They compared growth curves in IQ and daily-living skills to kids who waited for services.
The team asked: does EIBI speed up the slope of learning over a year?
What they found
Children in EIBI climbed faster on IQ and adaptive tests than the wait-list group.
Kids who started with higher IQ or got more hours each week climbed fastest.
Still, every child’s line looked different—some steep, some flat.
How this fits with other research
Eldevik et al. (2026) pooled 15 similar studies and saw the same faster slopes, so the new data sit inside the bigger picture.
Giallo et al. (2014) and Långh et al. (2021) add that starting before age 2 and using high-quality teaching makes the line even steeper.
Perry et al. (2019) followed kids ten years later and found the gains held, proving the speed-up is not a short-term blip.
Why it matters
You can show families a simple line graph: earlier, denser, better-quality ABA bends the curve upward.
Use the study when you fight for 30-plus hours and when you screen cognitive level at intake—both levers are now evidence-based.
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02At a glance
03Original abstract
Although still a matter of some debate, there is a growing body of research supporting Early and Intensive Behavioral Intervention as the intervention of choice for children with autism. Learning rate is an alternative to change in standard scores as an outcome measure in studies of early intervention. Learning rates can be displayed graphically as developmental trajectories, which are easy to understand and avoid some of the counter-intuitive properties of changes in standard scores. The data used in this analysis were from 453 children with autism, previously described by Eldevik et al. Children receiving Early and Intensive Behavioral Intervention exhibited significantly steeper developmental trajectories than children in the control group, in both intelligence and adaptive behaviors. However, there was a considerable variability in individual learning rates within the group receiving Early and Intensive Behavioral Intervention. This variability could partly be explained by the intensity of the treatment, partly by children's intake intelligence quotient age-equivalents. Age at intake did not co-vary with learning rate.
Autism : the international journal of research and practice, 2015 · doi:10.1177/1362361313510067