Lately I’ve been having lots of discussion on this topic, so I felt that perhaps it might benefit from a blog post all of its very own!

So what exactly is an aversive? Well, the term more correctly should be aversive stimulus.

A stimulus is anything that stimulates (triggers) a response. For example, an object, noise or movement. The term aversive refers to the properties of the stimulus.

An aversive stimulus is unpleasant or painful, and the response that it naturally creates is an escape or avoidance response.

So what are escape or avoidance responses?

We are talking about reflex responses here, the aversive stimulus triggers the body’s self defense mechanism, in other words, at an endocrine level, the stress response.

This is arousal of the sympathetic branch of the autonomic nervous system, more popularly known as fight or flight. So the threat of perceived or actual bodily harm created by the aversive stimulus triggers the body to release adrenaline, increasing the heart rate and respiration rate and preparing the muscles for activity.

The individual will then take action in order to either escape from or avoid the aversive stimulus. A mild stimulus will lead to a mild response, but as the stimulus increases in intensity, so will the response.

So aversive stimuli cause avoidance responses, which could be on a spectrum from a slight twitch through freeze, flight to fight.

And what is the affective (emotional) component of the aversive stimulus? In other words, how does the stimulus make the individual feel?

The basic emotion felt by an individual experiencing an aversive stimulus is fear. The intensity of fear will be directly related to the intensity of the stimulus, and so might range from mild discomfort through to full blown terror.

So, to summarise all that in simple, laymans terms:

An aversive stimulus causes an individual to feel frightened and to take action to avoid the stimulus, this could be through freezing, fleeing, or fighting. Fear and rage lie close together. Sometimes the response to a perceived threat could be fight.

The intensity of fear experienced will vary according to the intensity of the stimulus, and, perhaps more importantly, the perception of the individual. This perception will be coloured by the individual’s history, their personality, the stress levels at the time.

For example, if I were to stand too close to you, depending on your individual personality, sensitivity and prior experience, you might simply find it mildly irritating, enough to make you step back a little, or it may make you feel defensive and make you want to step towards me. Or you may find it threatening enough (frightening enough) to make you want to move quickly away or even leave the room/ call for help.

Here is a short list of just some of the stimuli that can be perceived as aversive by horses: physical pressure created by bits, legs, leadropes; driving pressure created by lungewhips or body language; pain caused by a bit, spurs or schooling whip; pain or discomfort due to ill fitting tack or poor riding;  fear of leaving the herd, to hack or travel in a trailer; veterinary treatment such as vaccinations or dental treatment. How many of these does your horse experience on a daily basis? Is there anything you can do to shift the balance for your horse?

The most important thing any horse trainer can do is to identify aversive stimuli when they are present (whether by accident or design), and recognise the impact they are having on the horse’s emotional wellbeing. It is a simple fact that the vast majority of horse training worldwide utilises aversive stimuli, the extent varying with the individual trainer and horse.

Does this statement cause YOU some discomfort? Perhaps you’d like to read my post on cognitive dissonance Let’s not get too emotional about it ;-). I’m not suggesting that we must never knowingly use aversive stimuli. What I’m saying is that we must recognise them, understand them, and make good judgement about their appropriateness in any given moment for any given horse.

Take a look at and to understand better the wider impact that aversive stimuli can have on your relationship with your horse and, perhaps more important, your horse’s relationship with the world.

Still feeling uncomfortable? How about you start exploring the potential of building more appetitives into your training? This can be incredibly simple to do, and sometimes the smallest changes can make the biggest difference. For example, a dressage rider I have been working with recently wanted to improve her medium trot without getting harder on her horse. I suggested that as soon as he even thought of responding to her aids and giving her the first step or two of medium trot, she should verbally praise him, make a downwards transition, forwards to halt, and feed him a treat. Within just a few repetitions he was moving forward enthusiastically and she was able to stretch the number of medium steps she asked for before rewarding him. Just the tiniest shift in how she did things had a huge impact on his motivation. And the lovely thing for me is that she is now exploring how we can build more and more of this type of work into his training, including, but not limited to, the use of a clicker. From small acorns…. :-).