Units of analysis in acquisition‐performance criteria for “mastery”: A systematic replication

Wong et al. (2022) asked a simple question: should we call a skill "mastered" when every single item hits criterion, or when the whole set averages 100%?

They taught sight words in discrete trials. In one condition the learner had to get each word right nine times out of ten before moving on. In the other condition the whole set of words had to average 100% correct.

Three participants alternated between the two mastery rules while the team counted trials and checked next-week retention.

Individual-word mastery won. All three participants reached the final performance goal in fewer trials when each word had to pass on its own.

Maintenance scores one week later were the same for both rules, so the faster route did not cost long-term recall.

Chang et al. (2024) ran the same comparison with four children and got the same result: checking each tact individually cut trials to criterion. The replication two years later strengthens the claim.

Cordeiro et al. (2022) extended the idea to tacts, intraverbals, and listener responses in kids with autism. Again, target-level mastery beat set-level mastery, showing the rule works across skill types.

Kodak et al. (2020) seems to disagree. They found bigger stimulus sets (6–12 items) produced faster tact learning than smaller sets. The difference is the mastery unit: Kodak kept the unit at the set level, while Wong moved it to the individual item. Smaller sets plus individual mastery is the sweet spot.

If you wait for an entire set to score 100% before advancing, you may waste trials on items already mastered. Flip the criterion to the single item and you let mastered words drop out early, shrinking total teaching time. The evidence now spans sight words, tacts, intraverbals, and listener skills across typical learners and children with autism. Next time you write a mastery check, require 90% on each target, not the whole set, and watch the session count fall without hurting maintenance.