Table of Contents
The Fundamental Concept of Motivating Operations (MOs)
Motivating Operations (MOs) represent a crucial and dynamic concept within the science of behaviorism, specifically addressing the variables that momentarily influence the effectiveness of environmental consequences within operant conditioning. Fundamentally, an MO is an environmental event or condition that executes a dual function: it temporarily alters the reinforcing or punishing value of a specific stimulus, and simultaneously alters the frequency of all behaviors that have historically been successful in producing or avoiding that consequence. This mechanism provides a sophisticated explanation for the variability in motivation and drive, moving beyond static stimulus-response models to account for why an organism’s “wants” or “needs” fluctuate rapidly and dramatically, thereby initiating or suppressing specific actions at any given moment. MOs serve as the behavioral analogue for internal motivational states, providing objective, measurable environmental variables that explain shifts in behavioral probability.
The core principle governing the Motivating Operation revolves around the constant fluctuation between states of deprivation and satiation relative to potential reinforcers. Consider the example of food: if an individual has been in a state of food deprivation for an extended period, this deprivation acts as an MO that significantly increases the effectiveness of food as a reinforcer. Consequently, the individual is far more likely to engage in behaviors previously associated with obtaining food, such as preparing a meal or visiting a restaurant. Conversely, if the individual has recently reached a state of satiation following a substantial meal, this satiation acts as an MO that diminishes or abolishes the reinforcing effectiveness of food, thereby reducing the probability of food-seeking behaviors. This understanding of fluctuating motivational variables is indispensable for practitioners, allowing them to precisely predict and influence behavior by manipulating the environmental conditions that establish or abolish the value of specific consequences.
Historical Evolution and Terminology of MOs
The formal introduction of this motivational concept into the field of applied behavior analysis (ABA) is credited primarily to the work of the influential behavior analyst, Jack Michael, around 1980. Michael initially coined the term “Establishing Operation” (EO) to describe the phenomenon where an environmental event—such as deprivation—increases the effectiveness of a subsequent consequence, thereby “establishing” the need. Prior to this development, traditional operant theory focused heavily on discriminative stimuli (SDs), but lacked a robust conceptual framework to account for the temporary, non-learned changes in motivation and drive observed constantly in both experimental and natural settings. The EO filled this critical gap by providing a functional analysis of why an organism would suddenly show an increased or decreased desire for a known reinforcer, even when the availability of that reinforcer remained constant.
A significant and crucial refinement to the terminology occurred in 2004 when the term was officially updated from “Establishing Operation” to the more comprehensive “Motivating Operation” (MO). This revision was enacted to ensure the terminology was symmetrical and accurately captured the full range of motivational effects. The original term, EO, seemed only to describe the operation of increasing a reinforcer’s value. However, the phenomenon also necessarily includes the opposite effect: decreasing a reinforcer’s value, which is formally known as the abolishing operation. Therefore, the umbrella term, Motivating Operation, serves to accurately encompass both the establishing operation (which increases the consequence’s effectiveness and makes behavior more likely) and the abolishing operation (which decreases the consequence’s effectiveness and makes behavior less likely). This evolution highlights the commitment within behavior analysis to achieving precise, functional, and conceptually accurate terminology that reflects the complexity of motivational control.
The Dual Effects: Value-Altering and Behavior-Altering
Every Motivating Operation exerts two distinct, simultaneous effects that define its function: the value-altering effect and the behavior-altering effect. The value-altering effect refers to the immediate change in how effective a specific stimulus or consequence is perceived as a reinforcer or punisher. For instance, if an MO of extreme cold is introduced—perhaps stepping into a poorly heated room—this operation immediately establishes warmth as a highly potent positive reinforcer, significantly increasing its value. Conversely, an abolishing operation, such as the satiation that follows consuming a large quantity of a specific candy, immediately decreases the future reinforcing value of that candy. This value-altering component is critical because it dictates what the organism is currently motivated to obtain or avoid, setting the stage for subsequent actions.
The second essential component is the behavior-altering effect, which describes the immediate change in the frequency or intensity of behaviors that have historically been reinforced by the relevant consequence. This effect can be further broken down into two manifestations: the evocative effect and the abative effect. When an MO is establishing (e.g., severe lack of sleep), it immediately evokes or brings forth behaviors previously successful in obtaining sleep, such as lying down or closing one’s eyes. This is not a newly learned behavior, but rather a temporary, immediate increase in the rate of an entire class of related behaviors. Conversely, when the MO is abolishing (e.g., having just completed a satisfying rest), it immediately abates or suppresses those same sleep-seeking behaviors. It is imperative to note that the behavior-altering effect is transient; the change in behavioral frequency persists only as long as the MO is in effect, distinguishing it sharply from the permanent changes in behavioral repertoire achieved through reinforcement and learning schedules.
Unconditioned versus Conditioned Motivating Operations (UMOs and CMOs)
Motivating Operations are systematically classified into two broad categories based on the origin of their motivational power: Unconditioned Motivating Operations (UMOs) and Conditioned Motivating Operations (CMOs). Unconditioned Motivating Operations are those whose value-altering effects are innate and do not require any prior learning history to be effective in altering behavior. These UMOs are inextricably linked to fundamental biological needs and survival mechanisms. Prime examples include deprivation of food, water, oxygen, and sleep, as well as the presentation of painful stimulation or exposure to uncomfortably high or low temperatures. The effectiveness of these operations is largely uniform across a species; for instance, water deprivation will universally increase the reinforcing value of water for any human, regardless of their individual life experiences or cultural background.
In contrast, Conditioned Motivating Operations are those whose motivational properties are entirely acquired through learning and association with other environmental events, often through systematic pairing with established reinforcers, punishers, or UMOs. CMOs gain their power because they have been consistently related to the ability to gain or lose access to other consequences. The most pervasive example of a CMO in human society is money. Money itself holds no biological significance, but deprivation of money acts as an incredibly powerful MO because, through extensive learning history, it has become associated with the acquisition of countless unconditioned reinforcers, such such as food, shelter, comfort, and safety. The vast complexity of human motivation in social, economic, and educational settings is largely driven by these CMOs, which explains the enormous variability in what motivates different individuals based on their unique, learned histories and specific cultural contexts.
Illustrating MOs: Thirst as a Real-World Example
To demonstrate the functional cycle of a Motivating Operation in a relatable context, consider the common experience of working outdoors on a hot, dry day and becoming thirsty. This scenario clearly delineates the function of the MO from other antecedent controls on behavior, such as the discriminative stimulus (SD). The process unfolds in a predictable sequence rooted in physiological and environmental interaction.
Deprivation State (The MO is Established): Following several hours of intense physical activity under dehydrating conditions, the individual’s body enters a physiological state of water deprivation. This state immediately functions as an establishing operation (a type of UMO) for water.
Value-Altering Effect Occurs: As a direct result of the MO of deprivation, water instantaneously acquires an extremely high reinforcing value. A simple glass of water is now far more valuable to the individual than it was prior to the labor, or than any non-essential alternative reinforcer might be, such as a soft drink or a snack.
Behavior-Altering Effect Occurs (Evocation): The MO immediately and powerfully evokes an array of water-seeking behaviors that have been reinforced by fluid consumption in the past. These behaviors might include walking toward the known location of the water cooler, actively searching for a water bottle, asking a colleague for a drink, or making a verbal request for “Water, please.” The frequency and intensity of this class of behaviors increase dramatically and instantaneously.
Satiation (The MO is Abolished): Once the individual consumes a sufficient quantity of water to restore hydration, the state of deprivation ends, and the body achieves satiation. This new physiological state acts as an abolishing operation (a type of MO), causing the reinforcing value of water to plummet rapidly, and immediately suppressing (abating) all further water-seeking behaviors, even if a half-full water bottle remains readily available.
Differentiating MOs from Discriminative Stimuli (SDs)
A frequent source of conceptual confusion in behavior analysis involves clearly distinguishing between a Motivating Operation (MO) and a Discriminative Stimulus (SD). Both are antecedent events that occur before a behavior and influence its probability, yet their functions are fundamentally different. The SD serves as a signal regarding the differential availability of reinforcement; it essentially tells the organism, “If you perform this specific behavior *now*, the consequence is available.” For example, a lit “Walk” sign (SD) signals that crossing the street (behavior) will result in safe passage (reinforcement). The SD is therefore primarily concerned with knowing if reinforcement is accessible.
In contrast, the MO signals the differential effectiveness of reinforcement; it tells the organism, “How much do you *want* the available reinforcement?” The MO does not provide information about whether the reinforcer is available, but rather about the current potency or value of that reinforcer if obtained. For instance, the sight of a vending machine stocked with candy (SD) signals that candy is available. However, if the individual is completely full (an MO of food satiation), the candy has little to no reinforcing value, and the SD will likely fail to evoke vending machine use. Conversely, if the individual is starving (an MO of food deprivation), the SD will strongly evoke the behavior because the reinforcer is highly effective. Therefore, the SD controls behavior because of the availability of reinforcement, while the MO controls behavior because of the current effectiveness of that reinforcement. For behavior to occur at a high probability, both a relevant SD and a relevant MO must typically be present.
Significance and Clinical Application in ABA
The introduction and refinement of the Motivating Operation concept constitutes one of the most significant theoretical and practical advancements in applied behavior analysis (ABA) since the initial formulation of operant principles. Its profound importance stems from its ability to provide clinicians with a powerful, manipulable tool for understanding, predicting, and influencing complex human behavior that might otherwise be mistakenly attributed to internal, unobservable factors like willpower or inherent motivation. In clinical settings, particularly those addressing challenging behaviors such as aggression, self-injury, or defiance, understanding MOs is absolutely critical for conducting a thorough Functional Behavior Assessment (FBA).
During an FBA, behavior analysts use MO principles to precisely determine the environmental function (or purpose) maintaining a problem behavior. If a child engages in throwing objects, the analyst must determine if the behavior is evoked by an MO of attention deprivation (making attention highly reinforcing) or perhaps an MO related to escaping a difficult academic task (making escape highly reinforcing). Once the prevailing MO is identified, highly effective intervention strategies can be designed by manipulating the environment to either abolish the MO for the unwanted behavior or establish an MO that makes an alternative, appropriate behavior highly probable. For instance, if a student screams solely because they are deprived of attention, the intervention might involve providing frequent, non-contingent attention throughout the day (abolishing the MO) so that attention-seeking screaming is no longer a necessary or effective strategy for obtaining the desired consequence.
Advanced Analysis: Categories of Conditioned Motivating Operations
To analyze the nuanced motivational control over complex human behavior, particularly verbal behavior, behavior analysts often utilize sub-categories of Conditioned Motivating Operations (CMOs). B.F. Skinner, in his seminal work Verbal Behavior, laid the groundwork for these distinctions, which are now broadly applied across all types of conditioned action. These categories provide a detailed framework for understanding how learned needs drive interaction, communication, and problem-solving.
CMO-Surrogate (CMO-S): A CMO-S acquires its motivational effectiveness by being systematically paired with a UMO or another established MO. Essentially, a neutral stimulus is repeatedly presented just before or during a state of deprivation or satiation, and eventually, the neutral stimulus alone evokes the motivational state. For example, if a specific chime sound is always paired with the time when a patient typically receives a necessary medication (a UMO related to pain reduction), the sound of the chime alone may eventually function as a CMO-S, increasing the reinforcing value of the medication and evoking medication-seeking behavior, even if the pain level is currently low.
CMO-Transitive (CMO-T): A CMO-T makes something else necessary as an intermediate step to obtain a desired reinforcer. It establishes its own removal as a reinforcer, but only because that removal allows access to a more ultimate, primary reinforcer. The classic illustration involves a tool or object required to complete a task. The deprivation of a specific tool, such as a screwdriver needed to open a battery compartment, acts as a powerful CMO-T. The screwdriver itself is not inherently reinforcing, but the deprivation of it makes the screwdriver highly reinforcing because obtaining it is necessary to gain access to the ultimate reinforcer (e.g., the toy inside the compartment). CMO-Ts are fundamental to understanding complex problem-solving and manding (requesting) for tools or assistance.
CMO-Reflexive (CMO-R): A CMO-R acquires its effectiveness by consistently preceding and signaling either an imminent worsening or improvement of conditions. It alters the reinforcing value of its own avoidance or removal. For instance, a stimulus that reliably precedes a difficult or punitive situation (e.g., a critical look from a supervisor before being assigned extra work) functions as a CMO-R. This stimulus establishes its own avoidance as a powerful negative reinforcer and immediately evokes behaviors designed to postpone or prevent the impending negative event. This type of MO is essential for analyzing the maintenance of escape and avoidance behaviors, and is deeply linked to constructs like anxiety and fear.