In our behavior practice, if a child stops crying at the thought of getting in the pool, or a horse stops trying to spin away from a flapping tarp—at first glance it looks like we’ve had success changing the behavior. (Check out many a dog training-themed TV show, where the dog’s fearful or reactive behavior is magically resolved within the hour, to see this phenomenon in action.) But the appearance on the surface doesn’t always tell the story underneath.

When we’re unsettled or unhappy with a particular behavior, we want it to stop. But just because a learner stops a behavior doesn’t always mean they’re feeling safe or that they understand what we want them to do instead.

Picture three scenarios:

1) A kid afraid of heights is sent up the small climbing wall over their protests;

2) A soccer goalie worried about getting hurt by penalty shots is kept in net for every shootout at practice;

3) The dog who barks at the vacuum is put in her crate while the vacuum runs in the same room.

In each of these instances, with no foreseeable life-or-death consequences at stake, we might feel OK compelling the learner on the assumption that "they'll get used to it." But what is the exact mechanism behind this type of learning?

Distinguishing between flooding, habituation, desensitization, and desensitization with counter-conditioning (CC) will help us to understand the mechanisms behind each of these techniques, and when it may or may not be appropriate to use them.

Here's an all-too-common example of how flooding can be tricky for observers to identify: A horse trainer posts a short video on social media. In the video, the trainer is standing in a barn aisle next to a horse that is standing tied to the wall. The trainer is holding a long, thin stick with a small piece of cloth at the end, called a training flag. The trainer slowly runs the flag along the horse's back leg. The horse kicks each time. The trainer continues touching the horse with the flag in repeated cycles, without reducing intensity or providing an escape option. Many viewers in the comments described this training technique as "desensitization."

It's not.

This is flooding, or full-intensity exposure to a stimulus with no escape possible. The horse is restrained and apparently feeling overwhelmed enough to kick at the flag. The trainer continues presenting the flag at that same intensity and duration for the entire the video. We presume the trainer's intent is to present the flag repeatedly so that the horse stops kicking. But when the horse finally stops reacting to the touch of the flag, do we know understand the mechanism got us there, or what emotions run underneath?

Let’s take a look.

Let’s compare:

Using any of these techniques, the final, changed behavior might look similar from the outside. But how the learner feels and what they learn are worlds apart.

Flooding carries significant ethical baggage. In human therapy, it requires informed consent. Why? Because when it goes wrong, it can go very wrong.

A 1991 study by Pitman et al. found that flooding therapy for PTSD sometimes triggered complications like increased depression, panic attacks, and even relapse of alcoholism. Flooding does not address shame, guilt, or prior trauma. It may even worsen them.

For animal trainers, this is a problem because animals can't give informed consent. Animals can't tell us, "Yes, I understand the risk of psychological fallout, but I’d like to proceed."

Other studies and historical case reports echo the same warnings:

In short, flooding might lead to the extinction of behavior, but at what cost?

We have opportunities every day to use or avoid flooding in our attempts to change behavior. We ourselves have probably experienced flooding at the hands of well-meaning parents, teachers, and coaches while we were in the process of learning a new skill or dealing with a new situation. For example:

Everyday events don't always give us the luxury of implementing textbook-inspired behavior change. Emergencies and accidents aren't often conducive to teaching moments, and that's OK.

If we realize after the fact that flooding occurred, we can give the learner post-event emotional and behavioral support.

There’s an important difference between taking a calculated risk on flooding—for health, safety, or a one-time event—and choosing as professionals to build teaching and training plans around flooding as a regular strategy. Using flooding because we think it will work “faster,” or because we believe it’s more effective than other behavior change strategies, or because we don’t want to adjust the environment or use positive reinforcement, doesn’t serve our learners well.

When in doubt, we ask: Does the learner feel safe and in control? If not, it might be time to slow down or change course.

Trainers, behavior consultants, coaches, and the like are often called upon to help a learner whose behavior may become dangerous to themselves and others. The social media trainer working with the horse is sure to care about horses, and was likely focused on hoof care, husbandry and public health and safety. Horses require regular hoof cleanings and farrier visits to live long, healthy lives. Even non-horse folks watching the video may say the horse wasn't showing signs of outright panic.

And flooding, like many techniques that rely on unpleasant experiences, can change behavior.

But psychologist Susan Friedman, Ph.D., reminds us that “effectiveness is not enough.” In her extensive writing on humane and ethical training practices, she explains that we must judge behavior-change methods not only by whether they work, but by how they work.

Friedman encourages trainers to consider how intrusive a method is before pushing full steam ahead: How much control the learner has, how much discomfort is involved, and whether the approach protects the animal’s emotional well-being. A method that stops a behavior we don't like but that causes fear or distress may meet a short-term goal, but it does not meet a humane standard.

One risk is that flooding often leads to behavioral suppression. The learner may stop reacting, but they haven’t built a reliable, functional, or confident response to use in place of the original reaction. So while it might look successful in the moment, the behavior often returns under stress—or generalizes to new problem behaviors (e.g., avoidance, aggression, shutdown). And flooding tends to involve a loss of control, overwhelming exposure, and few or no coping tools, which can increase fear or mistrust.

Research and clinical reports suggest that while flooding can decrease observable responses, it carries a higher risk of emotional distress and relapse compared to gradual exposure methods. For that reason, flooding is rarely the best long-term strategy and is usually not in the learner’s best interest.

When a learner stops reacting, it doesn’t automatically mean they feel better about the situation.

A conditioned emotional response (CER) is a learned emotional reaction to a stimulus. For example, if a dog has had frightening experiences with a vacuum, the sound of the vacuum alone may trigger fear. Effective desensitization — especially when combined with counter-conditioning — works by changing that emotional response. Over time, the vacuum no longer predicts danger, and fear decreases.

Behavioral suppression, on the other hand, means the our ability to observe the behavior decreases. The learner may stop barking, kicking, or resisting, but the underlying fear may still be present. Suppression can occur for many reasons, including fatigue, restraint, inescapable exposure, or loss of control, without improving how the learner actually feels.

Remember our earlier examples of flooding? Let’s look at how we might approach each of them without using flooding—by teaching what to do, not just waiting for the behavior to change.

When we want a learner to stop an unwanted behavior, we can scrutinize our process to make sure we're not accidentally introducing flooding. Take the time to ask these questions anytime you're implementing a protocol to combat fear or anxiety: