Comparison of Blocked Versus Mixed Trialing When Teaching Foundational Skills to Early Learners
Blocked and mixed trials finish in a dead heat when teaching basic skills to preschoolers with autism.
01Research in Context
What this study did
McKeown et al. (2025) asked a simple question. Do preschoolers with autism learn faster when trials are blocked by target or when targets are mixed within the same set?
Four children worked on basic matching and listener tasks. Every day the program flipped between blocked and mixed formats. The team tracked how many trials each child needed to hit mastery.
What they found
Both ways taught the skills in about the same time. No child showed a clear win for either format.
The authors call it a draw: blocked trials do not slow learning and mixed trials do not speed it up for these early learners.
How this fits with other research
Syriopoulou-Delli et al. (2012) once showed that blocked trials helped one child master identity matching without any fading steps. McKeown’s group widens the lens to four kids and still sees safe, solid learning—good replication across time.
Schnell et al. (2018) used the same alternating-treatments design with preschoolers and also found that the "best" method can flip from child to child. The new data echo that message: individual fit matters more than the layout.
Levesque-Wolfe et al. (2021) proved that preschoolers with autism can learn safety rules through discrete trials. McKeown adds that, for simpler discriminations, you can pick either blocked or mixed trials without hurting acquisition.
Why it matters
If you worry that blocked trials will create faulty stimulus control, relax. Use the format that keeps your learner engaged and your session flowing. Try both, watch the data, and stay with the one that feels smoother for that child—because speed comes out the same either way.
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Run one target in blocked trials and the next in mixed; graph daily and keep the layout that gives fewer problem behaviors.
02At a glance
03Original abstract
ABSTRACTWhen teaching discriminations, clinicians may choose to teach one target at a time, repeatedly, until mastery (blocked‐trial instruction), or they may choose to teach multiple targets, interspersed, simultaneously (mixed‐trial instruction). Historically, it was recommended clinicians use mixed‐trial instruction at the onset of teaching as blocked‐trial instruction may produce faulty stimulus control. However, a recent study demonstrated that a modified blocked‐trial instructional arrangement was more efficient than mixed‐trial instruction and block‐size fading was unnecessary to maintain discriminated performance in adults with intellectual and developmental disabilities. The generality of these results to early learners is unknown. This study extended the aforementioned research to early learners diagnosed with autism spectrum disorder. Using an adapted alternating treatment design, we compared the rate of acquisition with both instructional formats across two foundational early learner skills. Comparable learning across both formats for all four early learners was observed.
Behavioral Interventions, 2025 · doi:10.1002/bin.2071