Introduction and Definition of Terms

When a horse is worried about something, he doesn’t pay much attention to you. That’s when his ‘arousal’ level is high.

A horse can also be optimistic or pessimistic—he can expect a new experience to be positive or negative. That’s his ‘emotional state’.

His level of arousal and emotional state taken together are his ‘affective state’ and dictate the quality of work he is capable of and what kind of reinforcement will be most effective for training at that moment.

Being able to read a horse’s affective state and respond appropriately in the moment could make the difference between raising his arousal level further until he can no longer interact with you and making significant progress towards your goal, whether that goal is quality time with him or higher steps in piaffe.

How Arousal is Created

We don’t yet know exactly what levels of arousal are ideal for training new behaviours. However, common sense and practical experience agree that if the horse is not aroused enough (if he is asleep), or if he is too aroused (if he fears for his life), there will be little useful interaction between horse and human.

Determining what level of arousal will be best for the intended activity with a horse could greatly benefit the interaction. For a therapy session, a very relaxed horse with a low level of arousal is preferred. For resolving a behaviour problem, a higher level of arousal will be needed so the horse is motivated to trial new responses and find the correct one. For shaping a trained behaviour, medium arousal will be best, so the horse can think about what is being asked.

How Negative Affective States are Created

We know more about negative affective states than positive because animal welfare criteria used to be based on the absence of negatives rather than the presence of positives. Positive experiences were finally introduced in the 2020 Five Domains Model.

When a horse’s expectations of the outcome of certain behaviours or events are not met, the difference between expectations and actual outcome creates frustration. Frustration in any or all of the four physical domains (Nutrition, Physical Environment, Health, and Behavioural Interactions) will create a negative state in the fifth Mental domain. This negative state can contribute to aggressive behaviour and, if frustration continues, will create a long term negative outlook. The use of punishment in training can also contribute to a negative state.

How Positive Affective States are Created

Use of the principles of equitation science in training has been shown to help avoid negative affective states during training. For welfare, however, it is not enough to avoid the negative. Working actively to help create a positive experience for the horse will contribute to positive affect and relationship.

In a study by Freymond et al, horses trained with addition reinforcement (where something pleasant is given to the horse to reinforce correct behaviour) were found to have more positive emotional states than those trained with subtraction reinforcement (where something

unpleasant is taken away to reinforce correct behaviour). Interestingly though, after the training session the subtraction-reinforced horses experienced a more positive overall emotional state than the addition-reinforced horses had. This suggests that trainers and owners employing combined reinforcement (use of both addition and subtraction reinforcement) may be able to positively influence their horse’s mood.


Awareness of how a horse is currently feeling is a great asset to any horse person. This knowledge makes it easier to predict what the horse will do in any given situation, enhancing safety and even making it possible to change plans to create a positive experience for the horse.

Keeping the lowest level of arousal required for the activity is essential to good training, positive welfare, and good relationship. Not everything in the human-horse relationship is going to contribute to a positive emotional state (for example, horses are unlikely to ask for a vaccination!), but even the negatives can be countered in other ways to develop an overall positive affective state in a horse.


Creighton, E. (2007) Equine learning behaviour: limits of ability and ability limits of trainers. Behav. Process. 76, 43–44.

Freymond SB; Briefer EF; Zollinger A; Gindrat-von Allmen Y; Wyss C; and Bachmann I. (2014) Behaviour of horses in a judgment bias test associated with positive or negative reinforcement. Appl. Anim. Behav. Sci. 158, 34–45.

Mellor, DJ; Beausoleil, NJ; Littlewood, KE; McLean, AN; McGreevy, PD; Jones, B; and Wilkins, C. (2020) The 2020 Five Domains Model: Including Human-Animal Interactions in Assessments of Animal Welfare. Animals 10, 1870. Open access: 2076-2615/10/10/1870

Olczak, K., Nowicki, J., and Klocek, C. (2016) Motivation, stress, and learning–critical characteristics that influence the horses’ value and training method–a review. Ann. Anim. Sci. 16, 641–652.

Starling, MJ; Branson, N; Cody, D; and McGreevy, PD. (2013) Conceptualising the Impact of Arousal and Affective State on Training Outcomes of Operant Conditioning. Animals 3. Open access:

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