What is the best reinforcement schedule?

I know that the partial reinforcement schedules > continuous reinforcement (less likely to go extinct).

Does this mean the hierarchy is like this?

Variable ratio > fixed ratio > variable-interval > fixed-interval ?

Or are the ratio and interval categories not comparable? (ie, Variable ratio > fixed ratio

variable-interval > fixed-interval but no relationship between them)

The schedule for reinforcement refers to the timing and frequency of the delivery of reinforcement after the toddler performs the skill/behavior. Reinforcement is delivered either continuously or intermittently.

Generally, continuous reinforcement means the reinforcement is delivered each time the toddler uses the skill/behavior until the skill/behavior is learned. Continuous reinforcement helps the toddler learn new skills quickly, but can lead to satiation. Once the toddler learns the behavior, as evidenced by them meeting a pre-established criterion, the reinforcement may be delivered intermittently. Intermittent reinforcement helps to maintain the skill/behavior over time, and should be used after the toddler learns the new skill/behavior.

Moving from a continuous to an intermittent schedule of reinforcement is an example of reinforcement fading. Fading of reinforcement is an important step to helping the toddler learn to use the skill without the need of secondary reinforcers so that he or she can better generalize the target skill/behavior to other people, places, and activities. Intermittent reinforcement schedules can be either ratio or interval. Ratio schedules deliver reinforcement after the toddler does the skill/behavior. Interval schedule reinforcement is provided after a certain amount of time has passed.

Both ratio and interval schedules can be fixed or variable. Once the toddler learns the skill better, using these schedules ensures higher rate of success since the toddler isn’t aware of when reinforcement will be provided. Providers and families generally use a variable schedule as they provide reinforcement. At home, mom and dad have their attention pulled in various directions and will find it more challenging to provide reinforcement for every occurrence of the toddler’s skill/behavior. The following chart describes in more detail the differences between these reinforcement schedules.

The following video shows an example of fixed ratio reinforcement and variable ratio reinforcement.

In determining the best schedule for providing reinforcement to the toddler remember the following:

General continuous reinforcement is best as the toddler learns a new skill.
Fixed schedules are more effective for shaping behavior.
Variable schedules are useful for helping a toddler maintain a skill.

The following table summarizes the different reinforcement schedules:

Schedules of reinforcement are the precise rules that are used to present (or to remove) reinforcers (or punishers) following a specified operant behavior. These rules are defined in terms of the time and/or the number of responses required in order to present (or to remove) a reinforcer (or a punisher). Different schedules schedules of reinforcement produce distinctive effects on operant behavior.

Interval Schedule

Interval schedules require a minimum amount of time that must pass between successive reinforced responses (e.g. 5 minutes). Responses which are made before this time has elapsed are not reinforced. Interval schedules may specify a fixed time period between reinforcers (Fixed Interval schedule) or a variable time period between reinforcers (Variable Interval schedule).

Fixed Interval schedules produce an accelerated rate of response as the time of reinforcement approaches. Students' visits to the university library show a decided increase in rate as the time of final examinations approaches.

Variable Interval schedules produce a steady rate of response. Presses of the "redial" button on the telephone are sustained at a steady rate when you are trying to reach your parents and get a "busy" signal on the other end of the line.

Ratio Schedule

Ratio schedule require a certain number of operant responses (e.g., 10 responses) to produce the next reinforcer. The required number of responses may be fixed from one reinforcer to the next (Fixed Ratio schedule) or it may vary from one reinforcer to the next (Variable Ratio schedule).

Fixed Ratio schedules support a high rate of response until a reinforcer is received, after which a discernible pause in responding may be seen, especially with large ratios. Sales people who are paid on a "commission" basis may work feverously to reach their sales quota, after which they take a break from sales for a few days.

Variable Ratio schedules support a high and steady rate of response. The power of this schedule of reinforcement is illustrated by the gambler who persistently inserts coins and pulls the handle of a "one-armed bandit."

Extinction

A special and important schedule of reinforcement is extinction, in which the reinforcement of a response is discontinued. Discontinuation of reinforcement leads to the progressive decline in the occurrence of a previously reinforced response.

Glossary Index | Quotations

Learning Objectives

Distinguish between reinforcement schedules

Remember, the best way to teach a person or animal a behavior is to use positive reinforcement. For example, Skinner used positive reinforcement to teach rats to press a lever in a Skinner box. At first, the rat might randomly hit the lever while exploring the box, and out would come a pellet of food. After eating the pellet, what do you think the hungry rat did next? It hit the lever again, and received another pellet of food. Each time the rat hit the lever, a pellet of food came out. When an organism receives a reinforcer each time it displays a behavior, it is called continuous reinforcement. This reinforcement schedule is the quickest way to teach someone a behavior, and it is especially effective in training a new behavior. Let’s look back at the dog that was learning to sit earlier in the module. Now, each time he sits, you give him a treat. Timing is important here: you will be most successful if you present the reinforcer immediately after he sits, so that he can make an association between the target behavior (sitting) and the consequence (getting a treat).

Once a behavior is trained, researchers and trainers often turn to another type of reinforcement schedule—partial reinforcement. In partial reinforcement, also referred to as intermittent reinforcement, the person or animal does not get reinforced every time they perform the desired behavior. There are several different types of partial reinforcement schedules (Table 1). These schedules are described as either fixed or variable, and as either interval or ratio. Fixed refers to the number of responses between reinforcements, or the amount of time between reinforcements, which is set and unchanging. Variable refers to the number of responses or amount of time between reinforcements, which varies or changes. Interval means the schedule is based on the time between reinforcements, and ratio means the schedule is based on the number of responses between reinforcements. Table 1. Reinforcement Schedules

Reinforcement Schedule	Description	Result	Example
Fixed interval	Reinforcement is delivered at predictable time intervals (e.g., after 5, 10, 15, and 20 minutes).	Moderate response rate with significant pauses after reinforcement	Hospital patient uses patient-controlled, doctor-timed pain relief
Variable interval	Reinforcement is delivered at unpredictable time intervals (e.g., after 5, 7, 10, and 20 minutes).	Moderate yet steady response rate	Checking Facebook
Fixed ratio	Reinforcement is delivered after a predictable number of responses (e.g., after 2, 4, 6, and 8 responses).	High response rate with pauses after reinforcement	Piecework—factory worker getting paid for every x number of items manufactured
Variable ratio	Reinforcement is delivered after an unpredictable number of responses (e.g., after 1, 4, 5, and 9 responses).	High and steady response rate	Gambling

Now let’s combine these four terms. A fixed interval reinforcement schedule is when behavior is rewarded after a set amount of time. For example, June undergoes major surgery in a hospital. During recovery, she is expected to experience pain and will require prescription medications for pain relief. June is given an IV drip with a patient-controlled painkiller. Her doctor sets a limit: one dose per hour. June pushes a button when pain becomes difficult, and she receives a dose of medication. Since the reward (pain relief) only occurs on a fixed interval, there is no point in exhibiting the behavior when it will not be rewarded.

With a variable interval reinforcement schedule, the person or animal gets the reinforcement based on varying amounts of time, which are unpredictable. Say that Manuel is the manager at a fast-food restaurant. Every once in a while someone from the quality control division comes to Manuel’s restaurant. If the restaurant is clean and the service is fast, everyone on that shift earns a $20 bonus. Manuel never knows when the quality control person will show up, so he always tries to keep the restaurant clean and ensures that his employees provide prompt and courteous service. His productivity regarding prompt service and keeping a clean restaurant are steady because he wants his crew to earn the bonus.

With a fixed ratio reinforcement schedule, there are a set number of responses that must occur before the behavior is rewarded. Carla sells glasses at an eyeglass store, and she earns a commission every time she sells a pair of glasses. She always tries to sell people more pairs of glasses, including prescription sunglasses or a backup pair, so she can increase her commission. She does not care if the person really needs the prescription sunglasses, Carla just wants her bonus. The quality of what Carla sells does not matter because her commission is not based on quality; it’s only based on the number of pairs sold. This distinction in the quality of performance can help determine which reinforcement method is most appropriate for a particular situation. Fixed ratios are better suited to optimize the quantity of output, whereas a fixed interval, in which the reward is not quantity based, can lead to a higher quality of output.

In a variable ratio reinforcement schedule, the number of responses needed for a reward varies. This is the most powerful partial reinforcement schedule. An example of the variable ratio reinforcement schedule is gambling. Imagine that Sarah—generally a smart, thrifty woman—visits Las Vegas for the first time. She is not a gambler, but out of curiosity she puts a quarter into the slot machine, and then another, and another. Nothing happens. Two dollars in quarters later, her curiosity is fading, and she is just about to quit. But then, the machine lights up, bells go off, and Sarah gets 50 quarters back. That’s more like it! Sarah gets back to inserting quarters with renewed interest, and a few minutes later she has used up all her gains and is $10 in the hole. Now might be a sensible time to quit. And yet, she keeps putting money into the slot machine because she never knows when the next reinforcement is coming. She keeps thinking that with the next quarter she could win $50, or $100, or even more. Because the reinforcement schedule in most types of gambling has a variable ratio schedule, people keep trying and hoping that the next time they will win big. This is one of the reasons that gambling is so addictive—and so resistant to extinction.

In operant conditioning, extinction of a reinforced behavior occurs at some point after reinforcement stops, and the speed at which this happens depends on the reinforcement schedule. In a variable ratio schedule, the point of extinction comes very slowly, as described above. But in the other reinforcement schedules, extinction may come quickly. For example, if June presses the button for the pain relief medication before the allotted time her doctor has approved, no medication is administered. She is on a fixed interval reinforcement schedule (dosed hourly), so extinction occurs quickly when reinforcement doesn’t come at the expected time. Among the reinforcement schedules, variable ratio is the most productive and the most resistant to extinction. Fixed interval is the least productive and the easiest to extinguish (Figure 1).

Figure 1. The four reinforcement schedules yield different response patterns. The variable ratio schedule is unpredictable and yields high and steady response rates, with little if any pause after reinforcement (e.g., gambler). A fixed ratio schedule is predictable and produces a high response rate, with a short pause after reinforcement (e.g., eyeglass saleswoman). The variable interval schedule is unpredictable and produces a moderate, steady response rate (e.g., restaurant manager). The fixed interval schedule yields a scallop-shaped response pattern, reflecting a significant pause after reinforcement (e.g., surgery patient).

Skinner (1953) stated, “If the gambling establishment cannot persuade a patron to turn over money with no return, it may achieve the same effect by returning part of the patron’s money on a variable-ratio schedule” (p. 397).

Figure 2. Some research suggests that pathological gamblers use gambling to compensate for abnormally low levels of the hormone norepinephrine, which is associated with stress and is secreted in moments of arousal and thrill. (credit: Ted Murphy)

Skinner uses gambling as an example of the power of the variable-ratio reinforcement schedule for maintaining behavior even during long periods without any reinforcement. In fact, Skinner was so confident in his knowledge of gambling addiction that he even claimed he could turn a pigeon into a pathological gambler (“Skinner’s Utopia,” 1971). It is indeed true that variable-ratio schedules keep behavior quite persistent—just imagine the frequency of a child’s tantrums if a parent gives in even once to the behavior. The occasional reward makes it almost impossible to stop the behavior.

Recent research in rats has failed to support Skinner’s idea that training on variable-ratio schedules alone causes pathological gambling (Laskowski et al., 2019). However, other research suggests that gambling does seem to work on the brain in the same way as most addictive drugs, and so there may be some combination of brain chemistry and reinforcement schedule that could lead to problem gambling (Figure 6.14). Specifically, modern research shows the connection between gambling and the activation of the reward centers of the brain that use the neurotransmitter (brain chemical) dopamine (Murch & Clark, 2016). Interestingly, gamblers don’t even have to win to experience the “rush” of dopamine in the brain. “Near misses,” or almost winning but not actually winning, also have been shown to increase activity in the ventral striatum and other brain reward centers that use dopamine (Chase & Clark, 2010). These brain effects are almost identical to those produced by addictive drugs like cocaine and heroin (Murch & Clark, 2016). Based on the neuroscientific evidence showing these similarities, the DSM-5 now considers gambling an addiction, while earlier versions of the DSM classified gambling as an impulse control disorder.

In addition to dopamine, gambling also appears to involve other neurotransmitters, including norepinephrine and serotonin (Potenza, 2013). Norepinephrine is secreted when a person feels stress, arousal, or thrill. It may be that pathological gamblers use gambling to increase their levels of this neurotransmitter. Deficiencies in serotonin might also contribute to compulsive behavior, including a gambling addiction (Potenza, 2013).

It may be that pathological gamblers’ brains are different than those of other people, and perhaps this difference may somehow have led to their gambling addiction, as these studies seem to suggest. However, it is very difficult to ascertain the cause because it is impossible to conduct a true experiment (it would be unethical to try to turn randomly assigned participants into problem gamblers). Therefore, it may be that causation actually moves in the opposite direction—perhaps the act of gambling somehow changes neurotransmitter levels in some gamblers’ brains. It also is possible that some overlooked factor, or confounding variable, played a role in both the gambling addiction and the differences in brain chemistry.

continuous reinforcement: rewarding a behavior every time it occurs

fixed interval reinforcement schedule: behavior is rewarded after a set amount of time

fixed ratio reinforcement schedule: set number of responses must occur before a behavior is rewarded

operant conditioning: form of learning in which the stimulus/experience happens after the behavior is demonstrated

variable interval reinforcement schedule: behavior is rewarded after unpredictable amounts of time have passed

variable ratio reinforcement schedule: number of responses differ before a behavior is rewarded