Most reinforcement schedules ask, "Did the person respond?" Time-based schedules ask only, "Has the time passed?" That one change makes them a powerful tool for reducing problem behavior and easy to mix up with schedules that look similar.
Why it matters
When a functional analysis shows that a behavior is maintained by attention, escape, or access to items, one of the simplest and most widely used treatments is to give that reinforcer freely on a clock. This is noncontingent reinforcement (NCR), and it runs on a time-based schedule. It is easy for teachers and caregivers to learn, it makes sure the client keeps contact with an important reinforcer, and it often lowers problem behavior quickly.
Time-based schedules also explain an unwanted effect: behavior that happens to occur right before a "free" reinforcer can be strengthened by accident. As a BCBA you need to design the schedule, choose a starting density, thin it, and watch for that accidental pairing.
Key ideas
- Time-based schedules are response-independent. The reinforcer arrives when the time is up, no matter what the person is doing. No response is needed, and no response can make it come sooner or later.
- Fixed vs. variable. On a fixed-time (FT) schedule the time between deliveries is the same every time (FT 2 min: every 2 minutes). On a variable-time (VT) schedule the time varies around an average (VT 2 min: sometimes 1 minute, sometimes 3, averaging 2).
- They are not interval schedules or DRO. FI and VI need a response after the time passes; DRO needs the problem behavior to be absent. FT and VT need nothing.
- Why NCR reduces problem behavior. Two processes are usually involved:
- Frequent free access acts as an abolishing operation: the reinforcer is worth less in the moment, so behavior that has produced it becomes less likely.
- When NCR is combined with extinction, problem behavior no longer produces the reinforcer, so the response-reinforcer relation is weakened.
- Choose the reinforcer by function. Use the reinforcer identified in the functional assessment (attention, breaks, a tangible). When that is not possible, for example with automatically maintained behavior, a competing stimulus is often used instead: an item shown in a competing-stimulus assessment to lower the behavior while the person has it, since preference alone is not enough.
- Start dense, then thin. Begin with a rich schedule, often near continuous access or an interval shorter than the typical time between problem responses in baseline. Once problem behavior stays low, lengthen the interval gradually toward a level that people can keep up in daily life.
Definitions
- Fixed-time (FT) schedule: a reinforcer is delivered after a set amount of time, independent of behavior.
- Variable-time (VT) schedule: a reinforcer is delivered after amounts of time that vary around an average, independent of behavior.
- Noncontingent reinforcement (NCR): an antecedent intervention that delivers a reinforcer on a time-based schedule, independent of the problem behavior. Some authors call the term a misnomer, because reinforcement implies a contingency; "fixed-time" or "variable-time delivery" is more precise.
- Adventitious reinforcement: accidental strengthening of a behavior that happens to occur just before a reinforcer, even though the reinforcer did not depend on it. The behavior it produces is sometimes called superstitious behavior.
Examples from a session
Time-based schedules in practice
- Clinic, attention function: Imani, 7, yells to get adult attention. Her plan gives 10 seconds of praise and conversation every 60 seconds (FT 1 min), and yelling no longer produces extra attention. Yelling drops within a few sessions.
- Classroom, escape function: Theo, 12, tears up worksheets to escape writing tasks. His teacher gives a 1-minute break on a VT 4-min schedule, whatever he is doing. Tearing a worksheet no longer ends the task, and he completes the work between breaks.
- Day program, automatic function: Rosa, 34, hums loudly in a way that disrupts her coworkers. Staff give her headphones with music for 5 minutes every 15 minutes as a competing stimulus.
- Thinning the schedule: Once Imani's yelling stays near zero for several sessions, her BCBA moves from FT 1 min to FT 90 s, then FT 2 min, checking the data at each step.
- Non-example: A teacher praises Ben, 8, for the first hand raise after each 5-minute timer ends. A response is required once the time passes, so this is fixed-interval, not fixed-time.
Common mistakes / exam traps
- Thinking NCR teaches a new skill. NCR reduces motivation for problem behavior; it does not build a replacement behavior. Pair it with teaching a functional alternative such as a mand when that is appropriate.
- Thinning too fast. Jumping from a dense schedule to a lean one often brings problem behavior back. Thin in small steps and let the data guide each step.
- Ignoring accidental pairings. If deliveries often land right after problem behavior, they can strengthen it. Some plans add a brief delay before delivery when problem behavior has just occurred.
Exam trap
The trap: fixed-time vs. fixed-interval. Both run on a clock, so ask whether a response is needed once the time is up. "The first response after 5 minutes" is FI. "Every 5 minutes, whatever the person is doing" is FT.
Exam trap
The trap: fixed-time (NCR) vs. DRO. Ask whether problem behavior can cancel or delay the reinforcer. In DRO, an occurrence resets the interval or forfeits that delivery. On FT, the reinforcer arrives on time even right after problem behavior.
Quick check
Every 5 minutes, a teacher checks on Jai, 10. She praises him only if he has not shouted at any point during those 5 minutes; otherwise she restarts the timer. Which arrangement is this?
Related topics
- Simple schedules of reinforcement: FR, VR, FI, and VI (B.9)
- Motivating operations in action (B.16)
- Differential reinforcement (DRA, DRO, DRL, DRH) with and without extinction (G.2)
- Maintaining change after intervention: schedule thinning and natural reinforcers (G.16)
- Designing and evaluating functional analyses (F.6)