Reinforcer

Reinforcer

Primary Disciplinary Field(s): Psychology (Behaviorism), Experimental Analysis of Behavior, Operant Conditioning

1. Core Definition and Context

The concept of the reinforcer is fundamental to the field of behaviorism, particularly within the framework of operant conditioning pioneered by B.F. Skinner. Functionally, a reinforcer is defined strictly by its effect on future behavior: it is any stimulus, object, or event that, when made contingent upon a specific response, increases the probability or frequency of that response occurring again in the future. Crucially, the definition is retrospective and empirical; an item is only a reinforcer if it demonstrably strengthens the preceding behavior. If an outcome does not increase the future rate of the behavior it followed, it is not considered a reinforcer, regardless of whether it was intended to be or if the individual subjectively enjoyed it. This scientific, results-oriented definition distinguishes it sharply from more common lay terms such as “reward.”

The mechanism by which reinforcement operates involves a three-term contingency, often referred to as the “ABC model”: Antecedent, Behavior, and Consequence. The consequence (the presentation or removal of the reinforcer) acts upon the behavior, strengthening the association between the behavior and the environmental context (the antecedent). For instance, in the classic example provided, if an individual says “hello” (Behavior) in the presence of a specific person (Antecedent), and subsequently receives one dollar (Consequence), the dollar functions as a reinforcer only if the frequency of that individual saying “hello” to that specific person increases thereafter. This contingency demonstrates the essential principle: behavior is learned and maintained by its consequences.

Understanding the context is critical, as reinforcement is entirely dependent on the organism and its current state. What functions as a powerful reinforcer for one individual (e.g., money or social praise) may have little or no reinforcing effect on another. Furthermore, the effectiveness of a reinforcer can fluctuate based on factors like deprivation and satiation; an organism deprived of food will find food highly reinforcing, whereas an organism that has recently eaten to satiety will find food reinforcement weak or nonexistent. Therefore, the successful application of reinforcement requires careful monitoring and individualized assessment of the environmental stimuli that reliably lead to behavioral increases.

2. Historical Context: Operant Conditioning

The conceptual precursor to the reinforcer lies in the work of Edward Thorndike, specifically his 1898 formulation of the Law of Effect. This law stated that responses followed by satisfaction (or a “satisfying state of affairs”) are more likely to occur again, while those followed by discomfort are less likely. While fundamental, Thorndike’s language was subjective, relying on internal states like “satisfaction.” B.F. Skinner formalized this concept in the mid-20th century, developing the experimental methodology of operant conditioning that allowed for the objective study of behavior. Skinner replaced subjective terms with precise, measurable terminology, focusing solely on the observable relationship between a response and the consequential event, thus establishing the rigorous definition of the reinforcer as a functional entity.

Skinner’s contribution was not merely linguistic but methodological. Through experiments utilizing the operant chamber (often called the Skinner Box), he demonstrated that complex behaviors could be systematically shaped and maintained by controlling the presentation of reinforcers. He clearly differentiated operant behavior—behavior controlled by its consequences—from respondent (or classical) behavior, which is elicited by antecedent stimuli (as studied by Pavlov). In the operant model, the reinforcer is the driving force that selects and strengthens adaptive behavior, much like natural selection shapes species characteristics over time.

The formal definition and classification of the reinforcer allowed behaviorism to move beyond simple reflex study into the realm of complex human and animal action. The framework provided a powerful tool for behavioral prediction and control, influencing subsequent psychological research and therapeutic practices. The development of schedules of reinforcement (discussed below) further refined the understanding of how behavioral persistence is established, showing that the timing and consistency of the consequential event are just as important as the nature of the reinforcer itself.

3. Fundamental Types of Reinforcers

Reinforcers are typically classified into two primary categories based on the nature of the consequence: positive and negative. It is critical to note that the terms “positive” and “negative” in this context do not refer to the subjective pleasantness or unpleasantness of the event, but rather to the mathematical operation applied to the environment: addition (+) or subtraction (-).

Positive Reinforcement occurs when a desirable stimulus is presented or added to the environment immediately following a behavior, resulting in an increase in the future frequency of that behavior. Examples include receiving a treat after completing a task, getting a paycheck after work, or being praised after giving a presentation. The stimulus added (the treat, the money, the praise) is the positive reinforcer. Positive reinforcement is generally the most common and ethically preferred method for strengthening behavior because it builds new skills and behavioral repertoires based on incentive and reward.

Negative Reinforcement occurs when an aversive or undesirable stimulus is removed, terminated, or avoided following a behavior, resulting in an increase in the future frequency of that behavior. A common misconception is that negative reinforcement is synonymous with punishment; however, this is inaccurate. Negative reinforcement always strengthens behavior. Examples include taking an aspirin to remove a headache (the removal of pain strengthens the likelihood of taking aspirin in the future), or buckling a seatbelt to stop the annoying warning chime (the removal of the chime strengthens seatbelt use). The behavior is reinforced because it successfully removes the negative condition.

Beyond the positive/negative dichotomy, reinforcers are also categorized by their origin: Primary (Unconditioned) Reinforcers are inherently effective without prior learning, as they satisfy basic biological needs (e.g., food, water, warmth, sexual contact). Secondary (Conditioned) Reinforcers acquire their reinforcing properties through association with primary reinforcers or other established secondary reinforcers. Money is the quintessential secondary reinforcer; it has no inherent value but can be exchanged for primary reinforcers. Generalized secondary reinforcers, such as attention or tokens, are powerful because they have been paired with a wide variety of other reinforcing stimuli.

4. Schedules of Reinforcement

While continuous reinforcement (reinforcing every single instance of the desired behavior) is essential during the initial acquisition phase of a new behavior, it is highly impractical for maintaining behavior over the long term and leads to rapid extinction when the reinforcement stops. For maintenance, durability, and resistance to extinction, intermittent or partial schedules of reinforcement are employed. These schedules dictate when and how frequently a response will be reinforced and profoundly affect the pattern and persistence of the reinforced behavior.

Intermittent schedules are divided into four main types, based on whether the contingency is determined by the number of responses (Ratio schedules) or the passage of time (Interval schedules), and whether the requirement is constant (Fixed) or changes unpredictably (Variable).

• Fixed Ratio (FR): Reinforcement is delivered after a fixed, predetermined number of responses (e.g., FR 10 requires 10 responses per reinforcement). This schedule produces high rates of responding, often followed by a brief post-reinforcement pause.
• Variable Ratio (VR): Reinforcement is delivered after an average, but variable, number of responses (e.g., VR 10 averages 10 responses). This schedule produces the highest and most steady rates of responding, with virtually no post-reinforcement pause, and is highly resistant to extinction (e.g., gambling).
• Fixed Interval (FI): Reinforcement is delivered for the first response that occurs after a fixed period of time has elapsed (e.g., FI 5 minutes). This results in a scallop-shaped response pattern, where responding is slow immediately after reinforcement and increases rapidly as the interval nears completion.
• Variable Interval (VI): Reinforcement is delivered for the first response that occurs after a variable, unpredictable period of time has elapsed (e.g., VI 5 minutes). This produces a slow, moderate, but steady rate of responding without significant pauses, as the reinforcement delivery is always uncertain.

The choice of schedule is paramount in applied behavior analysis and educational settings. Variable schedules, particularly the Variable Ratio schedule, are the most effective for creating behaviors that are persistent and resistant to extinction, a critical factor when attempting to maintain skills long after formal training or intervention has ceased. Furthermore, the thinning of reinforcement—gradually moving from continuous to intermittent schedules—is a standard procedure for ensuring behavioral durability and transitioning control from external consequences to natural environmental consequences.

5. Differentiation and Related Concepts

The term reinforcer is often confused with terms like “reward” and “punishment.” A critical distinction must be maintained: reinforcement is defined solely by the strengthening of the behavior it follows, whereas a reward is a subjective judgment of pleasantness or desirability. A reward may or may not function as a reinforcer; for example, if a manager gives an employee a public commendation (a reward) but the employee subsequently avoids the behavior that earned the commendation due to embarrassment, the commendation did not function as a reinforcer.

The most common conceptual error involves confusing negative reinforcement with punishment. Both punishment and reinforcement are consequences that follow behavior, but they have opposite functional effects. Reinforcement (both positive and negative) always increases the likelihood or frequency of the behavior. Punishment (both positive punishment, adding an aversive stimulus, and negative punishment, removing a desirable stimulus) always decreases the likelihood or frequency of the behavior. For example, a child throwing a tantrum to gain attention is positively reinforced if the parent gives attention, increasing the tantrum behavior. If the parent spanks the child, and the tantrum behavior decreases, this is positive punishment. If the parent removes the child’s favorite toy, and the tantrum behavior decreases, this is negative punishment.

Another related concept is Extinction, which occurs when a previously reinforced behavior is no longer followed by the reinforcing consequence, resulting in the gradual decrease and eventual cessation of the behavior. The effectiveness of a reinforcer can also be influenced by Motivating Operations (MOs), environmental variables that momentarily alter the effectiveness of a reinforcer and alter the frequency of behavior that has been reinforced by that consequence. For example, being thirsty (an MO) increases the effectiveness of water as a reinforcer and increases the frequency of water-seeking behavior.

6. Significance and Applications

The principle of the reinforcer is perhaps the single most important concept derived from operant conditioning, forming the theoretical basis for a vast range of applied behavioral sciences. Its significance stems from its utility as a reliable mechanism for shaping, teaching, and maintaining complex behavioral chains in diverse populations.

In clinical and educational settings, the application of reinforcement is codified within Applied Behavior Analysis (ABA). ABA therapists utilize reinforcement principles to teach communication skills, social skills, and adaptive behaviors, particularly effective in treating individuals with autism spectrum disorder and other developmental disabilities. Techniques such as shaping rely entirely on differential reinforcement, where successive approximations of a target behavior are reinforced until the desired, complex behavior is achieved.

Beyond clinical applications, reinforcement principles are integral to organizational management, education, and animal training. In Organizational Behavior Management (OBM), positive reinforcement systems are used to increase productivity, improve workplace safety, and enhance employee morale. In education, reinforcement structures are used to encourage student engagement and academic persistence through token economies or contingency management systems. The widespread adoption of these techniques demonstrates the power of the reinforcer as a universal tool for behavioral change based on empirical principles rather than subjective judgment.

7. Criticisms and Ethical Considerations

Despite its robust empirical foundation and widespread success, the heavy reliance on external reinforcers has faced significant philosophical and ethical criticism, primarily concerning issues of control, manipulation, and the potential impact on intrinsic motivation. Critics argue that focusing exclusively on environmental control minimizes the importance of cognitive processes, free will, and internal states (e.g., thoughts and feelings).

A major area of debate centers on the overjustification effect. Psychologists such as Edward L. Deci and Richard Ryan argue that providing extrinsic reinforcement (e.g., money or prizes) for an activity that is already intrinsically rewarding can actually decrease an individual’s intrinsic motivation to perform that activity once the external reinforcement is withdrawn. While behavior analysts argue that reinforcement is necessary when intrinsic motivation is absent or insufficient to establish the behavior initially, the debate highlights the complexity of human motivation beyond simple stimulus-response contingencies.

Ethical concerns also arise when powerful reinforcers are used in environments where the individual has limited choice, such as institutional settings. Critics question whether the systematic application of reinforcement can be manipulative, reducing autonomy if the individual is unable to negotiate the contingencies or if the reinforcers selected are considered basic rights (e.g., access to food or social interaction). Proponents of ABA counter these criticisms by emphasizing the use of the least restrictive procedures, prioritizing positive reinforcement over aversive control, and focusing on teaching skills that increase the individual’s overall freedom and independence within their environment.

Further Reading

• Operant conditioning (Wikipedia)
• B. F. Skinner (Wikipedia)
• Applied Behavior Analysis (Wikipedia)
• Reinforcement (Wikipedia)