Every teaching program answers a quiet question: who decides when the learner gets to respond? In a trial-based arrangement, you do. In a free-operant arrangement, the learner does. That one difference shapes what you can teach, how you measure it, and what your data can and cannot tell you.
Why it matters
Both arrangements are common, and each has strengths. Trial-based teaching gives you many clear, controlled learning opportunities. Free-operant arrangements let the learner initiate, practice at their own pace, and contact natural reinforcers. If you pick the wrong arrangement, or the wrong measure for it, your graph can look great while the skill stays fragile.
This task belongs to Behavior-Change Procedures (domain G). Practice items here ask you to name the arrangement, match the measure to it, or pick the change that builds fluency or spontaneous responding.
Key ideas
- In a trial-based (discrete-trial) arrangement, the opportunity to respond is restricted. Each trial has a clear start and end: an antecedent such as an instruction, a response (with a prompt if needed), a consequence, and a short pause before the next trial. The learner cannot emit the next target response until you present the next trial.
- In a free-operant arrangement, the learner can respond at any time. Each response takes little time and leaves the learner free to respond again right away, so responding can range from very slow to very fast.
- The arrangement determines the measure. In trial-based teaching, the instructor sets the pace, so the learner's rate mostly reflects how fast trials were delivered. Measures such as percentage of trials correct and trials to criterion fit better. In free-operant arrangements, rate (count per unit of time) is the natural measure because the learner controls how often responses occur.
- Percentage correct has a ceiling; rate does not. Two learners can both score 100% correct while one answers in 2 seconds and the other in 15. Rate measures can show differences in fluency that accuracy alone hides.
- Trial-based teaching shines for early acquisition. Clear antecedents, planned prompting, and many opportunities per session help build new discriminations quickly and make data collection simple.
- Free-operant arrangements shine for initiation, fluency, and generalization. Naturalistic teaching, such as incidental teaching during play or routines, lets the learner start the interaction. Timed practice, such as one-minute timings, builds fluent responding.
- Blend them on purpose. Many programs teach a new skill in trials, then move it into timed practice and natural routines. Choose based on the skill, the learner's stage of learning, and the goal, not on habit.
Definitions
- Discrete trial: a teaching unit with a defined antecedent, a single response opportunity, and a consequence; the instructor controls when the next opportunity occurs. Also called a restricted or controlled operant.
- Free operant: a response that can occur at almost any time, takes little time to complete, and does not prevent the next response.
- Intertrial interval (ITI): the brief pause between the consequence of one trial and the antecedent of the next.
- Percentage correct: correct trials divided by total trials, multiplied by 100; useful when opportunities are fixed by the instructor.
- Rate: count of responses divided by observation time; the standard measure for free-operant responding.
- Fluency: accurate responding at a pace that supports retention, endurance, and use in real settings.
Examples from a session
Same skill, two arrangements
- Trial-based (clinic): Nia, age 4, sits with her RBT, who holds up a picture and says, "What is it?" Nia answers, receives praise or a correction, and the RBT pauses briefly before the next card. The RBT records each trial as correct or incorrect.
- Free-operant (home): During snack, Nia's favorite crackers sit in a clear container on the counter. Whenever Nia asks for them, her father hands her one. He counts her requests across the 15-minute snack.
- Timed practice (school): Marcus, age 12, has 100% accuracy on multiplication facts in trials. His teacher adds one-minute timings where he answers as many fact cards as he can, and records correct and incorrect answers per minute.
- Adult setting (vocational program): Elena, age 28, folds towels at her own pace during a work block. Her job coach records towels folded per minute, because Elena controls when each response happens.
- Non-example (near miss): Kim runs a "one-minute timing" for Jordan, age 6, but shows one card at a time and waits before the next. It is timed, yet Kim controls each opportunity, so it is still trial-based.
When you review a program, check whether the measure matches the arrangement. A trial-based graph in responses per minute mostly shows the instructor's pace. A free-operant graph in percentage correct can hide large changes in how often the learner responds.
Common mistakes / exam traps
- Treating 100% correct as mastery. Accuracy can be at ceiling while responding is still slow and effortful. Add a rate measure when fluency matters.
- Capping a timing with too few items. If the learner finishes the sheet before time is up, the count measures the sheet, not the learner. Give more items than the learner can complete.
- Assuming more trials will produce initiation. Trial-based practice teaches responding to an instructor's antecedent. If the goal is spontaneous requesting or commenting, arrange opportunities for the learner to start the interaction.
- Treating one arrangement as always better. The best choice depends on the skill and the stage of learning.
Exam trap
Trial-based vs. free operant: ask who controls the response opportunity. If the instructor does, think trials and percentage correct. If the learner does, think free operant and rate.
Exam trap
Rate vs. percentage correct in discrete trials: a rising responses-per-minute graph from trial-based sessions may only show that the instructor delivered trials faster. When the instructor sets the pace, judge acquisition by percentage correct or trials to criterion.
Quick check
At his day program, Kai, age 30, can play with any of five leisure items on a table at any time during a 5-minute session while staff record how long he engages with each item. Which arrangement does this describe?
Related topics
- Measuring occurrence: count, rate, and percentage (C.3)
- Measuring efficiency: trials to criterion, cost-benefit, and training time (C.7)
- Designing and evaluating preference assessments (F.4)
- Teaching simple and conditional discriminations (G.6)
- Programming for stimulus and response generalization (G.15)
- Maintaining change after intervention: schedule thinning and natural reinforcers (G.16)