A comparison of stimulus set size on tact training for children with autism spectrum disorder

The team taught new tacts to four children with autism. They tried four set sizes: 3, 4, 6, and 12 pictures in one lesson. An adult held up a card, said "What is it?", and gave praise or a token for a correct name. The same child saw a different set size each day. The goal was to see which size let the child reach mastery fastest.

Bigger sets won. Six-item and twelve-item sets taught the new words in fewer trials than the three-item and four-item sets. All four kids reached mastery faster when the pile held more pictures.

Vladescu et al. (2021) ran almost the same study with teens and got the opposite answer: 3-6 items beat 12. The two papers look like they clash, but the kids in Kodak were younger. Age may change the sweet spot.

Cordeiro et al. (2022) asked a different question: should we master each single word or the whole set? They found moving to one-word mastery cut sessions in half. Put together, Kodak says "use big sets" and Cordeiro says "check each word off quickly"—you can do both.

Zhi et al. (2023) kept the set-size game but added extra intraverbal facts during tact trials. Tacts still grew, showing the larger-set idea holds even when you pack more into each trial.

If you run discrete-trial tact programs, start with at least six exemplars per set for young learners. You will likely see mastery sooner and need fewer total sessions. Watch older kids or teens for signs of overload; they may do better with smaller sets as Vladescu showed. Either way, track individual-word criteria so you do not over-teach.