Remembering the Pre-Aversive Stimulus


There are some terms and concepts from behavioral psychology’s past that have found themselves buried in time. Tucked away in a journal here or there but largely forgotten. The older research that tracked rates of behavior following “noxious stimuli”, for example- A phrase we don’t use anymore.  Time has also changed the fascination with respondent conditioning and effects that just two (or more) paired stimuli somewhere along the line could change responding for a lifetime. Powerful principles, which with progress now seem so mundane. Somewhere in there, we have the pre-aversive stimulus.

The pre-aversive stimulus had a great role in early behavioral science animal research to describe responding patterns, but the concept easily applies to humans as well. A pre-aversive stimulus, simply put, is the stimulus that reliably precedes an aversive stimulus. Have you ever heard the term avoidance responding? Some people may call that “escape-maintained behavior” in the field but it is effectively just that- engaging in behavior (responding) to avoid a stimulus that was aversive in the past. Running away. Getting away. Dodging it. What signals that, then? The pre-aversive stimulus. It goes even further. Just through respondent conditioning, the pre-aversive stimulus can take on features of the aversive stimulus and become a conditioned aversive stimulus itself. Then there’s another pre-aversive stimulus that could reliably precede that, and with enough second-order conditioning, you could get messy (over)generalization and find all sorts of related stimuli as aversive. Generalized Anxiety Disorder theoretically works on this same principle. It’s not hard to see how this kind of thing can tangle up a person’s life- whether they are able to realize it and vocalize it or not.



Wait! Isn’t a pre-aversive stimulus just a kind of SD?

Let’s not jump to any conclusions and mistake a pre-aversive stimulus for an SD just yet. They have some things in common. They’re both stimuli (but so is almost everything else). They can both be considered antecedent stimuli when we look at the framework of the avoidance responding that sometimes follows them. They signal something. All good comparisons- but here’s a big distinction if you don’t remember: A discriminative stimulus (SD) signals reinforcer availability for a specific type of response.

The per-aversive stimulus does not necessarily have to.

In some situations, you could conceptualize a case for negatively reinforced behavior, but that might muddy the definitions of both terms being used concurrently. They speak to different phenomena even though they could describe one particular stimulus. The big difference is that the cue for available reinforcement is not necessary for a pre-aversive stimulus. It is simply a stimulus that has commonly preceded something aversive, or bad.

Example: An individual has been stung by a wasp before. Maybe several times if they were unlucky. Prior to the stinging, they heard the buzzing around a wasp nest.

That buzzing could likely become a pre-aversive stimulus, and through respondent conditioning, a conditioned aversive stimulus itself in the future.

In the research, pre-aversive stimuli tended to evoke “anxiety” in respondents- which was quasi-operationalized to the term conditioned emotional response (CER), also called conditioned suppression. That’s an important distinction to keep in mind. Here, a pre-aversive stimulus appears to suppress or decrease responding- not signal reinforcement for a response like an SD would.

Like freezing near a wasp nest when buzzing is heard. The usual comfortable walking pace (response) is suppressed in the presence of the buzzing sound (pre-aversive antecedent stimulus).



Anxiety! Conditioned Emotional Responses! Conditioned Suppression!

Respondent conditioning research has some fascinating lessons that are just as relevant today as they were decades ago. Sometimes in the day to day practice of behavior analysis- things get oversimplified for the sake of ease of practice.

Behavior goes up? Reinforcement is at work.

Behavior goes down? Punishment is at work.

To a degree, those definitions work. Even with our wasp nest example earlier, those initial stings could absolutely punish some future walking behavior. But we can’t forget about the little things- the little preceding stimuli that have so much to do with the actual phenomenon. The buzzing didn’t punish the walking. Don’t forget the antecedents. Don’t forget the respondent conditioning. Taking the time to examine just one more step explains the process so much more clearly.

What conditioned pre-aversive stimuli appear to evoke conditioned emotional responses in your day to day life? Do you see conditioned suppression of behavior, as a result, that would have otherwise been there? What pre-aversive stimuli could be “tagging on” to the effects of an aversive stimulus you’re aware of? Does it evoke any avoidance behavior?

Too simple? Laurence Miller ‘s (1969) work on compounding pre-aversive stimuli might whet your broader research appetite. Citation below.

Thoughts? Comment! Question! Like!



Coleman, D. A., Hemmes, N. S., & Brown, B. L. (1986). Relative durations of conditioned stimulus and intertrial interval in conditioned suppression. Journal of the Experimental Analysis of Behavior,46(1), 51-66. doi:10.1901/jeab.1986.46-51
Miller, L. (1969). Compounding of pre-aversive stimuli1. Journal of the Experimental Analysis of Behavior,12(2), 293-299. doi:10.1901/jeab.1969.12-293
Ormrod, J. E. (2016). Human learning. Harlow, Essex, England: Pearson.
Image Credits:, photographer Hubert Mousseign

Beer and Behavior Analysis


There’s been a shift in culture towards beer recently. Twenty years ago, if you saw the title “Beer and Behavior” you would absolutely expect a scathing speech of the abuses of the drink. This is not going to be that. I assume everyone reading this to be responsible. I’m interested in modern context. The beer industry has grown, become more varied, and those varieties have become more available. Craft brewing has taken off to previously unforeseen heights and different styles and personal recipes of beer are becoming available to the public like never before. It’s amazing. People are demanding more beer, and craft brewers are making it.

Now when there’s socially significant behavior out there, it can be studied. When people engage with their environment, their society, over something they want and will pay for it’s worth knowing how that works. I wanted to see how we could apply some of the concepts we use in Applied Behavior Analysis (ABA) to get an idea of it. Behaviors as the consumers, and behaviors as the provider. That’s where Midnight Oil Brewing Company came in to provide the setting for studying and some insights on what the process is like on both sides of the bar. That night, in particular, they had nine of their craft beers on tap and full-house of people engaging in operant behaviors to gain access to them.

Now let’s talk behavior.

Beer can be a Reinforcer. Think of a reinforcer as a type of stimulus that resembles a reward. What makes a reinforcer special is that it maintains or increases the likelihood of the behavior that precedes it. Think of it like this-

A person walks up to the bar and asks for a beer, maybe a Serenity session ale, the bartender pours that beer and hands it to them.

Assuming that the beer is what they like, and they find it reinforcing, the consumer would be likely to return to that same bar and order again. That’s reinforcement. To break it down further- The consumer’s behavior (requesting) operates on the environment for access to that beer. Access to the beer is socially mediated by talking to the bartender and the eventual exchange of money, but if they get access to the beer and like it, the reinforcement acts on that requesting behavior’s presentation in the future. The requesting behavior happens again or might even happen more often. There was a big if in there though. The beer had to be enjoyable, or reinforcing, to the individual for it to work. People have different tastes, and as you may be aware, not all people like all types of beer.


Beer Flights can be a Preference Assessment for Reinforcers. A preference assessment is a tool used to figure out which stimuli are reinforcing at a given time. This is done by a presentation of a varied set of stimuli to an individual, which they have access to and engage with, and eventually, you get a hierarchy from that. By looking at what gets chosen more, you can tell which stimulus a person likes best at that given moment. Preferred stimuli make for great reinforcers for behavior. Now at a taproom or bar, we can use these preference assessments to determine our own hierarchies of the types of beer we enjoy. This can help us weed out the types we do not like, which help us not select them in the future, from the types we do like.

A person has a flight of 9 beers in front of them. They try all nine, but only like and continue to drink the Stouts, Porters, and Saisons.

On the other side of the bar, a bartender can observe a person with a flight of beers, and use the information from watching what beers were selected and consumed at higher amounts, to make better suggestions for that person’s next choice to order. A little rapport building goes a long way. (I know that I tend to order more of the suggestions of a bartender that understands my preferences. Personal opinion-data point of one.). On the business side of things, having consumers choose a selection of beers they enjoy repeatedly can have long-term reinforcing tendencies on their return and future consumption. Imagine an example of a person mistakenly trying a few beers in a row of a style they dislike. This could punish beer seeking and buying behavior- the opposite of reinforcement. Knowing where to guide a consumer is useful information. The trend of behavior can go in both directions, and a preference assessment could be key in making the experience enjoyable for everyone.

Taprooms can employ J.R Kantor’s Setting Events to create an environment to facilitate engagement from consumers not only as paying customers but prosocially with one another. Some people call this ambiance. Some people call this the “feel” of a place. In early behavior analytic research, behaviorists like J.R Kantor were interested in antecedent stimuli, “things” in the environment that could either prime behavior, or discriminate (select) specific behaviors to occur. These are stimuli, variables in the environment, that may influence certain behaviors to occur over others.

Larger spaces with a higher number of tables could lead to a higher retention of served consumers, more bartenders responding to requests could lead to higher rates of (responsible) beer requests, larger tables could lead to groups forming, televisions playing a specific program could retain specific like-interested individuals, and play-oriented items like boardgames could provide alternative sources of reinforcement and retain consumers on the premises for longer.

The potential is endless, and many of these examples would have to be fine-tuned and tested for practicality, but these are all things that could be set in place before someone even steps foot in the door. Antecedents are powerful things. But Setting Events aren’t the only concepts out there that explore them- there are also Motivating Operations. We’ve talked about Reinforcers, and even Punishers. These are stimuli that have an effect on future behavior, but there was a great researcher named Jack Michael that noticed that there are factors that can momentarily affect the value of those stimuli, and the behaviors seeking them.

Thirst and Hunger can be Unconditioned Motivating Operations. When you see the word Motivating Operation, take the common well-known word of “Motivation” to guide your understanding of it. Unconditioned just means that it is something innate, or not learned. Unconditioned Motivating Operations (UMOs) are often based on natural biological drives, and in taprooms and bars, the most common ones we see are based on deprivation and satiation. Thirst is a great example of a UMO.

If a person is thirsty, a beer is more likely to be a strong reinforcer, and their behavior to seek it out is more likely. The same with hunger, as a UMO for food-seeking behavior, and food as a reinforcer.

The same, however, can go for satiation. If someone is full, that satiation acts as a UMO and abolishes the seeking behaviors and reinforcement value of food or drink.

Beer can involve Conditioned Motivating Operations too. Conditioned Motivating Operations (CMOs) are just like Unconditioned Motivating Operations; they momentarily alter the value of a reinforcer- like beer. The only difference is that these are conditioned, or learned. The research on these has been back and forth. Some say their effects are noteworthy, and others say these theories don’t hold much water. I think they can make a great way of conceptualizing how preferences, or reinforcement values, can be affected by a person’s learned history. To that end, I’m going to try and make a taproom, or beer example, for each type of CMO.

Surrogate Conditioned Motivating Operation (CMO-S)- A surrogate CMO is something that alters the value of a reinforcer because it has been paired with an Unconditioned Motivating Operation, and takes on its effects. Here’s a craft beer example:

Unconditioned Motivating Operation- Deprivation. The value of beer is going to be higher.

Surrogate Conditioned Motivating Operation- “Last Call”. The value of beer is going to be higher due to a paired deprivation scenario (UMO) in the past.

In these conditions, we can speculate that it would have a behavior-altering effect in the same way deprivation does, and a value-altering effect on the beer as a reinforcer for requesting right before time runs out. A deprivation (UMO) has been paired with the “Last Call” stimulus enough that it takes on some of that effect.

Reflexive Conditioned Motivating Operation (CMO-R)- A reflexive CMO alters the value of its own removal. Behaviorally, this is called “discriminated avoidance”. Learned avoidance to a specific thing. Basically- a person is presented with something, they’ve experienced it in the past as something aversive or bad, and they want to get away from it. Just the presentation is enough to cue behaviors to avoid it. Here is a personal Beer CMO-R I’ve experienced.

Conditioned Stimulus- A saison in the middle of a beer flight, which ruins the flavors of otherwise amazing beers tasted afterward.

Reflexive Conditioned Motivation Operation- Seeing the word Saison on a beer flight list. All behaviors that can get the bartender to NOT include it are altered (more likely).

Saisons (NS) are okay types of beers on their own, but again, personal data point of one, ruin the palate for the tastes that follow it when they are in a beer flight (CMO-R). The presentation of a saison in a beer flight is enough for someone (me) to engage in behavior for its removal.

Transitive Conditioned Motivating Operation (CMO-T)- A transitive CMO is something a little broader, and looser, conceptually. It involves an alteration of the value of another stimulus. Generally, through improvement. Like the other CMOs, this is also based on a persons learned history. Some traditional examples like to go for the blocking of a behavior chain, leading to another stimulus to solve it becoming more valuable. I much prefer the “My Friend Has That Beer And Now I Want It Too” transitive conditioned motivating operation conceptualization. For this to work, it requires a learned history of a friend that often selects delicious beer. This delicious beer paired history also has a discriminative quality of “being better” than the persons first choice before. Their friend just picks the better beer every time. It’s not fair. Let’s play it out like this.

Person’s Requesting Behavior: “I’d like an Insomnia Stout”.

Friend’s Order Afterwards: “I’d like you to layer this Doc Brown Ale with the Dark Matter Stout on top.”

Transitive Conditioned Motivating Operation- This value altering condition (Friend’s Order) may not have physically blocked the first response (Person’s First Request), but it is a stimulus presentation with a value altering effect strong enough create the need for a stimulus change.

Person’s Second Requesting Behavior: “NO WAIT! Cancel that first one. I also want that Doc Brown Ale with the Dark Matter Stout on top.”

What do you think? Has that happened to you before? Could it be explained by the transitive conditioned motivating operation? I think it just might.

So we’ve gone through some Behavior Analysis, and we’ve gone through some Beer. Do you have any other examples of common human behavior that could be explained by these terms, or others, behavior analytically?

Questions? Comments? Arguments? Leave them below!


Wahler, R. G., & Fox, J. J. (1981). Setting events in applied behavior analysis: Toward a conceptual and methodological expansion. Journal of Applied Behavior Analysis,14(3), 327-338. doi:10.1901/jaba.1981.14-327
Big Thanks:
to Midnight Oil Brewing Company

“Natural Selection” and Human Behavior


Let’s talk about evolution. Or better yet, let’s talk about human behavior, and how our understanding of it was influenced by evolutionary theory. For context, we will want to mention B.F Skinner, a researcher at Harvard in the 1950’s, who had far reaching impacts in the field of psychology, and an emerging practice of it called behaviorism, especially in its terminology and future usage. Most of his work is still held in great regard today, and although not taken as holy writ, has been the foundation of future research and adaptations of the original work. Skinner viewed behavior in a novel way, one influenced by Darwin’s evolutionary theory.

“Reflexes are intimately concerned with the well-being of the organism. Reflex behavior which involves the external environment is important in the same way. If a dog’s foot is injured when it steps on a sharp object, it is important that the leg should be flexed rapidly so that the foot is withdrawn… Such biological advantages “explain” reflexes in an evolutionary sense: individuals who are most likely to behave in these ways are presumably most likely to survive and pass on the adaptive characteristics to their offspring.” (Skinner, 1953).

His work on conditioning was different than that of Ivan Pavlov’s. While Pavlov worked with reflexes and stimulus pairing, specifically,  Skinner worked with learned (or operant) behavior and used the philosophical lenses of adaptation to do so.

“The process of conditioning also has a survival value. Since the environment changes from generation to generation, particularly the external rather than the internal, appropriate reflex responses cannot always develop as inherited mechanisms… Since nature cannot foresee, so to speak, that an object with a particular appearance will be edible, the evolutionary process can only provide a mechanism by which the individual will acquire responses to particular features of a given environment after they have been encountered. Where inherited behavior leaves off, the inherited modifiability of the process of conditioning takes over.” (Skinner, 1953).


Selection by Consequences

In Skinner’s theoretical framework for the analysis of behavior, he sets reflexes apart from behaviors omitted as a modifiable response to reoccurring conditions. Operant behavior that had been altered in some way by past consequences. Or, in layman’s terms; experience.

A behavior which occurs following an event with similar conditions to one experienced before, would either have taken on adaptive features to better access/avoid that stimulus, or, if the original behavior failed, would not be likely to omit again in those similar conditions. This is the foundation of behavioral learning theory, and what Skinner called “selection by consequences”.  This form of selection focuses on the consequences of their behavior in order to predict and describe the rate by which they occur in the future. Behaviors, in this sense, can either be strengthened or weakened via selection. We can see this in some of the terminology still used in behavioral science today:

Reinforcement- Responses from the environment that increase the probability of a behavior being repeated. (ie. When a behavior is “rewarded”, it happens more often).

Punishment- Responses from the environment that decrease the likelihood of a behavior being repeated (ie. When a behavior is “punished”, it happens less often).

Extinction- When a conditioned stimulus is no longer paired with an unconditioned stimulus. Or, if the learned (operant) behavior is no longer reinforced; leading to a decrease in future usage of that behavior. (ie. When there is no more “reward”, the behavior has no purpose to reoccur).


In each of these terms above we can see the impact of environmental conditions, and the usefulness of behavior, to describe and predict how it is used, and why. This had vast philosophical repercussions for psychology at the time. Viewing learning and experience in an evolutionary sense had wide reaching advantages in the field of psychology. During this period (1950’s), psychoanalysis was still the mainstay of many professionals, but had glaring weaknesses in treating habitual disorders, or even features within disorders. The Freudian “talking-cure” was adept at having individuals speak about their internal events, their past, and conceptualizing the Id, Ego, and Superego as explanatory factors for their behaviors and interpretations on their dreams and thoughts; but there was no direct observable translation to healthy action following this treatment. It also gave many professionals with similar training, wild variation in interpreting.



The Unconscious Mind vs. Selection By Consequences

One psychoanalyst might attribute excessive smoking to a childhood event, while another might attribute it to a symbol of the cigarette/flame itself. The explanation did not come from the event, or any clue from the environment around the individual; it was all estimation of events that could not be seen. When the past was used as a descriptor, it was often speaking of formative childhood and adolescent experiences, not the direct past or future. In a strict behavioral sense; these are explanatory fictions. Circular definitions that cannot be proven or disproven.

Comparing this to Skinner’s fledgling analysis of behavior, you can see the drastic differences in a hypothetical example of cigarette smoking:

Freudian- Psychoanalytic Interpretation (“The Unconscious Mind”) The unconscious mind acts as a repository, a cauldron, of primitive wishes and impulses… The making of a fire and everything connected therewith is filled through and through with sex symbolism. (Freud,  A General Introduction to Psychoanalysis.  1935)
Skinnerian- Behavior Analytic Interpretation (“Selection by Consequences”) The first time a cigarette was lit and smoked, that behavior was reinforced by the consequence (reinforcement). The probability of future smoking behavior was increased by which ever stimulus acted as a reinforcer (taste, chemical interaction, social, etc).


You will notice under the behavior analytic interpretation; the behavior is adaptive. If smoking that cigarette was pleasing to the individual, they would seek it more in the future. If it was aversive, they would be more likely to avoid it. It is adaptation within the lifetime of the individual. It requires no intergenerational passing of information or traits. It adapts because it serves a function.

Applications of the classifying of behaviors by function, complex social phenomena, and even verbal behavior itself have been conducted using this evolutionary-minded theory of why behaviors occur, and asking the question “for what reason?”. But this is not limited to direct experience. With this explanation, a behavior would not even need direct influence from a specific condition. This is where “rule-governed” behavior is explained. Let’s take a look at a rule governed behavior that might effect the smoking behavior above:

  • SURGEON GENERAL WARNING: Tobacco Smoke Increases The Risk Of Lung Cancer And Heart Disease, Even In Nonsmokers.

According to Skinner, the “rule” serves as a contingency specifying stimulus. Humans are able to learn from the experiences of others, and can adapt our behavior based on observation and instruction. Those stimuli serve as the consequences that either reinforce, or punish, behavior which in turn effects future probability of those behaviors being omitted.

One could either smoke a cigarette and find it displeasing, or they could be given a warning. Supposing that the cigarette, and the instruction, carried enough punishing value, the smoking behavior would decrease. Both are viable consequence events that can effect rates of future behavior.

This topic focused specifically on changes of behavior of an individual, but can also be used in much broader scope as well (especially with rule-governed behaviors). There is growing interest in the field researching was is called meta-contingencies. This theoretical framework does not exclude “thoughts” either, and labels them as “private events”, behaviors in their own right. While we may not touch on that today, keep these theories in mind. They might be adaptive for you.


Questions? Comments? Leave them below!


  1. Cooper, J. O., Heron, T. E., & Heward, W. L. (1987). Applied behavior analysis. Columbus: Merrill Pub. Co.
  2. Skinner, B. F (1945). The operational analysis of psychological terms. Psychological Review, 270-277.
  3. Skinner, B. (1960). Science and human behavior. New York: Mc Millan Company.
  4. Darwin, C. (1872). The origin of species. New York: D. Appleton.
  5. Freud, S. (1935). A general introduction to psychoanalysis. New York: Washington Square Press.


Image Credits:, Getty Images, North American Energy Advisory (2017)