A fixed interval schedule of reinforcement rewards behaviors after set periods of time. The interval of time between rewards is “fixed” and does not change, unlike other types of partial reinforcements like fixed variable schedules.
Strictly speaking, after the interval has elapsed, the very next occurrence of the goal behavior is rewarded. However, in practice, the fixed interval schedule is applied slightly differently, as can be seen in the fixed interval schedule examples below.
The fixed interval schedule is one of four schedules of intermittent partial reinforcement identified by B. F. Skinner. The four schedules are:
Each reinforcement schedule produces a unique set of behavioral patterns and contain different strengths and weaknesses.
Generally, an intermittent reinforcement will be instituted after the behavior has been learned as a way to prevent extinction. Prior to learning the behavior, continuous reinforcement is preferred.
Fixed Interval Schedule Overview
A fixed interval schedule gives reinforcement to the first instance of a behavior after a specific period of time has elapsed.
In a fixed interval, the time duration between rewards remains constant. Out of the four types of reinforcement schedules, the fixed interval schedule results in the least occurrence of the desired behavior. speed of acquisition and extinction is influenced by the length of the interval – shorter intervals lead to faster learning and faster fading of the behavior.
This schedule also produces a unique pattern of behavior called scalloping. Rate of behavior decreases immediately after reinforcement, and then shows a dramatic increase shortly before the next interval of time elapses.
|Fixed Interval Pros||Fixed Interval Cons|
|1. Easy to implement and understand||1. Lower response rates|
|2. Predictable reinforcement pattern||2. Scallop effect (increased response near reinforcement time)|
|3. Suitable for long-term behavior change||3. Less resistant to extinction|
Fixed Interval Schedule Examples
- John works at a fast-food restaurant and gets paid every two weeks.
- Stella doesn’t even open her school book until a few days before the exam. Then she studies a lot. After the test, she puts her book on a shelf and doesn’t look at it again until the next exam date approaches.
- Hakeem’s editor gives him an award at the end of the month to encourage him to keep writing his sci-fi book.
- Jasmine calls her long-distance boyfriend every Saturday morning to see how he is doing and express her love.
- Mrs. Jones gives her students a short quiz every Monday morning. She does this because she wants them to study over the weekend when they are least likely to pick-up their books.
- Coach Jacobs knows his team slacks off their conditioning during the winter off-season. So, he has the strength and conditioning coach assess the body fat of each player every two weeks. If they pass, then they don’t have to run as many laps when practice begins in the summer.
- Mrs. Singh checks on her teenagers every night at 8. If they’re finishing their homework, then they can play video games or talk on the phone with their friends for 30-minutes before bedtime.
- If Lisa and Mike are good, they know Santa will bring them lots of presents on Christmas. So, they start behaving especially well the weeks leading up to the holiday. Afterwards, well, that’s a different story.
- Ben has a dental appointment every 6 months. So, he takes care of his teeth and gums for a few weeks leading up to his appointment, then he gets lazy.
- Mr. Jones give his employees a bonus at the end of every quarter to encourage their hard work and dedication to the company.
- Mrs Jones knows one student tends to misbehave if left alone for more than 10 minutes, so after 8 minutes she checks in and gives him the attention he needs (this is a special type of fixed interval schedule used in the noncontingent reinforcement strategy of functional behavior analysis).
Case Studies of Fixed Interval Schedule
1. Training Your Dog
People with pet dogs know how important it is to let them go outside and play. The fresh air and exercise are good for their health.
But, like most dogs, they always want to play. So, every time you walk by the door, they get excited and think it’s time to go outside. That can get a bit annoying.
This behavior can be shaped by using a fixed interval schedule of reinforcement. It works like this:
- First, every day at 6 p.m. you give your dog a treat for sitting at the door, and then take them outside to play.
- The dog may sit at the door at other times, but it’s important that you don’t give the treat or take them outside at any other time.
- After several days of using this schedule, the dog will learn that every day at that time is when they will get a treat and go outside.
2. Keeping Young Learners On-Task
Keeping students focused on their classwork is a continuous challenge for all teachers, especially for teachers of young learners. Children are easily distracted and find it difficult to keep their attention on-task.
Riley et al. (2011) applied a fixed interval schedule of reinforcement to two students identified by a classroom teacher as having an especially hard time staying focused.
First, the children’s on-task and off-task behaviors were recorded during a baseline period. Next, the teacher was instructed to provide fixed-time (FT) delivery of teacher attention every 5 minutes.
The teacher offered praise for on-task behavior and redirected the student’s attention for off-task behavior.
The authors concluded that “This study demonstrates that FT attention delivery can be an effective strategy used to increase the on-task behaviors and decrease the off-task behaviors of typically-developing students” (p. 159).
3. The End OF Term Paper
Every university student has experienced the dread of having to write a term paper. It seems to be many professors’ favorite assignment. To add to the pressure, in some courses, the term paper can constitute as much as half of a student’s final grade.
The guidelines for the paper can sometimes be as detailed as the paper itself, with strict rules regarding everything from formatting to the number of references.
Ideally, most students would begin working on the paper early in the semester and make steady progress throughout the term. Unfortunately for most, this usually doesn’t happen. Most students wait until the very last minute to even get started.
Although this is an obvious mistake, it is completely understandable if you look at it from a fixed interval schedule of reinforcement.
The reward of being finished comes at the end of the term. Therefore, like most instances of fixed interval schedules, the rate of work is very low in the beginning. As the deadline/reinforcement interval approaches, behavior starts to increase dramatically.
4. Helping Children with Emotional and Behavioral Disorders
Some children with severe emotional and behavioral disorders can be too disruptive to regular classroom activities. Often, these children are referred to specialized day-treatment or hospital-based programs.
Rasmussen and O’Neill (2006) investigated the effects of a fixed-time schedule of reinforcement on decreasing disruptive behavior. Participants in the study were three children ages 8-12 years old that had been identified by public schools as having emotional and behavioral disorders.
The participants were placed in a day-treatment program classroom with seven to nine other students. The classroom contained a special education teacher and two psychiatric technicians.
The participants worked on academic activities involving writing, math, or social studies during three to four 10-minutes sessions each day, for 5 days per week.
The teacher was instructed to provide verbal praise or a pat on the arm on a fixed-time schedule of 10s or 20s, depending on the participant.
The impact on disruptive behavior was significant: “Implementation of FT schedules resulted in immediate, substantial, and stable decreases for all participants” (p. 455).
5. Work Habits of the U. S. Congress
The U. S. Congress works on a fixed interval work schedule. The begin in January and finish at the end of the year. Their goal behavior is passing bills of legislation.
If this is the case, then we should see a pattern of behavior that is typical of what is observed with the fixed interval schedule of reinforcement.
Critchfield et al. (2003) analyzed the annual congressional bill production over a period of 52 years, based on annual data from 1949 to 2000. The data were taken from the ‘‘Resume´ of Congressional Activity,’’ a feature of the annual Daily Digest volume of the Congressional Record (Washington, DC: United States Government Printing Office).
“Across all years surveyed, few bills were enacted during the first several months of each session, and the cumulative total tended to accelerate positively as the end of the session approached. Across more than half a century, then, bills have been enacted in a distinct scalloped pattern in every session of each Congress” (p. 468).
Downsides of Fixed Interval Schedules
- Of the four types of interval schedules, the fixed interval produces the lowest frequency of the goal behavior.
- It also exhibits a unique pattern that involves an increasing rate of the goal behavior just prior to the end of the interval.
- After the reward has been applied, the frequency of behavior drops. This pattern of behavior is often referred to as scalloping.
Fixed interval schedules of reinforcement come from the behaviorist theory of learning. It posits that behaviors can be shaped through simple rewards and punishments.
Within this theory, there are two branches: operant and classical conditioning.
- Operant conditioning refers to learning through repetition, reward, and positive punishment.
- Classical conditioning occurs when you subconsciously or unintentionally associate a stimulus with a response (also known as associative learning). For example, salivating when there is the smell of tasty food is an example of classical conditioning. It occurred at the subconscious level.
Fixed interval schedules can be used to condition behaviors within both operant and classical conditioning methods.
Related terms in classical conditioning include unconditioned response and unconditioned stimulus. We say a response or stimulus is ‘unconditioned’ if it is not chosen or explicitly selected by the teacher or researcher. Rather, the response is a natural and subconscious reaction to something in the environment.
Stimulus Generalization: In stimulus generalization, we tend to respond in the same way to multiple related stimuli. It often occurs to army veterans, for example, who jump at loud sounds. They have generalized the sound of explosions and other loud noises in an urban environment, leading to a strong fight or flight reaction that was necessary in war zones.
Response Generalization: In response generalization, we tend to respond to the same stimulus in multiple different ways. For example, a child may respond to a film by jumping up and down, squealing with job, or laughing, but each response generally means the same thing.
Stimulus Discrimination: In stimulus discrimination, we develop the ability to tell the differences between multiple related stimuli and respond accordingly. For example, a seasoned guitarist starts to tell the minute differences in tones of their strings, enabling them to perfectly tune a guitar by ear.
Conditioned Stimulus: A stimulus that would be neutral except for the fact someone has learned that the stimulus has meaning. As an example of a conditioned stimulus, a bell has no inherent meaning, but in the context of education, it might signify that it is time for recess, triggering a conditioned response.
Non-Associative Learning: This happens when our behavior changes when there’s no change to an associated stimulus. For example, over time, we may become desensitized to the sound of airplanes going over our home despite no changes in the amount or frequency of planes flying overhead.
The fixed interval schedule of reinforcement produces a unique pattern of behavior called scalloping. This pattern is typified by a dramatic increase in the goal behavior as the interval approaches, followed by a substantial drop, or post-reinforcement pause.
This can be seen in many everyday life situations. For example, students will often only begin studying for an exam or working on a term paper right before the interval is about to elapse. After the exam is administered, studying drops.
Congressional legislation shows a similar pattern. When the session begins, there is little productivity. However, as the session nears termination, a dramatic increase in productivity occurs.
In the classroom, teachers can deliver their attention to students on a fixed interval schedule that results in increased on-task and decreased off-task behaviors.
Critchfield, T. S., Haley, R., Sabo, B., Colbert, J., & Macropoulis, G. (2003). A half century of scalloping in the work habits of the United States Congress. Journal of Applied Behavior Analysis, 36(4), 465-486.
Ferster, C. B., & Skinner, B. F. (1957). Schedules of reinforcement. New York: Appleton-Century-Crofts.
Skinner, B. F. (1958). Reinforcement today. American Psychologist, 13(3), 94–99.
Morgan, D. L. (2010). Schedules of reinforcement at 50: A retrospective appreciation. The Psychological Record, 60, 151–172. https://doi.org/10.1007/BF03395699
Rasmussen, K., & O’Neill, R. E. (2006). The effects of fixed-time reinforcement schedules on problem behavior of children with emotional and behavioral disorders in a day-treatment classroom setting. Journal of Applied Behavior Analysis, 39, 453-457.
Reed P. (2001). Schedules of reinforcement as determinants of human causality judgments and response rates. Journal of Experimental Psychology. Animal Behavior Processes, 27(3), 187–195.
Riley, J. L., McKevitt, B. C., Shriver, M. D., & Allen, K. D. (2011). Increasing on-task behavior using teacher attention delivered on a fixed-time schedule. Journal of Behavioral Education, 20(3), 149-162.
Weisberg, P., & Waldrop, P. B. (1972). Fixed‐interval work habits of Congress. Journal of Applied Behavior Analysis, 5(1), 93-97.