Complex cognitive processes in horses identified in French study

A schematic representation of the learning apparatus. During the "contingency degradation phase", a zero contingency was associated with the square object and the pellets, and a positive contingency was associated with the round object and the oats. Image: Study in PLOS ONE
A schematic representation of the learning apparatus. During the “contingency degradation phase”, a zero contingency was associated with the square object and the pellets, and a positive contingency was associated with the round object and the oats. Image: Study in PLOS ONE

Horses that show high fearfulness in their personality may tend to develop habitual responses more easily than their more emotionally secure peers, research suggests.

The study indicated that horses were able to create a precise mental representation of the consequences of their actions.

The relationship between personality and learning abilities in animals has become a growing field of interest. However, studies have tended to focus on performance, such as the speed at which they learn.

Léa Lansade and her colleagues set up an experiment that involved what is known as a contingency degradation protocol.

The protocol essentially tested whether the horses were able to adjust their response when the likelihood of a particular reward changed, indicating that their actions were not simply a learned habitual response.

French researchers used 29 well-handled Welsh pony mares bred at the French National Institute for Agricultural Research to test their hypothesis that personality could have a bearing on the ease with which they changed from a goal-directed process to a learned habit.

The difference between the two is important.

A horse that develops a goal-directed process is aware of the consequences of its actions and, having grasped changes to the likelihood of receiving a reward, modifies its behaviour. The behaviour of such horses will thus be more flexible.

In contrast, horses that have developed a habit-type process will form a link between its action and the preceding stimulus, rather than its consequences.

“This subject will thus have a more rigid automatic behaviour and become less sensitive to changes in the value of the outcome, and in the causal relationship between the action and its consequence,” they noted.

In the experiment, the ponies learnt to give a nose poke to an object to receive a food reward. They were then trained with two objects at the same time, each associated with a specific food reward.

The ponies were then assessed when given altered scenarios for one of the objects, which ranged from being rewarded whether they touched it or not to an “extinction condition” under which there was no longer a reward.

An animal sensitive to contingency – that is, able to grasp the changing likelihood of a reward – would be expected to touch the unaffected object much more than the one that eventually provided no rewards.

Overall, they found that horses were sensitive to contingency degradation – the changes in the likelihood of success between their action and the reward.

The relative nose poke rates in the non-degraded and degraded conditions during the choice extinction test. Image: Study in PLOS ONE http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0171010
The relative nose poke rates in the non-degraded and degraded conditions during the choice extinction test. Image: Study in PLOS ONE

The study team then checked the results against the previously assessed personality profiles.

They found that horses who had been assessed as presenting high fearfulness, and to a lesser extent low sensory sensitivity and lower gregariousness, were less sensitive in this area, showing that they were more likely to switch to a habitual process.

Horses assessed as showing little fearfulness, or related dimensions such as stress vulnerability or anxiety, did better at the reward acquisition task, they found.

“We conclude that personality is not only related to learning performance, but also in part to the process involved during learning, independently of the emotion experienced during the process,” the study team reported in the open-access peer-reviewed journal PLOS ONE.

“This study provides proof that personality is not only linked to how much and how fast an individual can learn but also to the way it learns depending on the specific contributions of different systems: habit versus goal-directed.

“Furthermore, it provides new theoretical knowledge on cognitive skills in equine species, suggesting that ungulates such as horses can form a mental representation of the consequences of their actions.

“This,” they reported, “is the first time that a link between a specific personality profile and a predisposition to form habits has been demonstrated through an appropriate experimental procedure.

“The fact that overall, horses were able to adjust their response according to the contingency between their action and the reward is in itself significant because it provides new knowledge on the cognitive skills of an ungulate such as the horse.

“Indeed, the mental process underlying this ability is thought to be relatively sophisticated.”

Lansade and her colleagues said it was important to remember that the experimental procedure used was particularly complex to avoid different interpretation biases and involved giving a non-contingent reward, whatever the condition.

“Only the type of reward changed between the two conditions.

“The fact that the horses had different response rates according to the conditions shows that they were able to create a precise mental representation of the consequences of their actions and of which reward was associated with each action.

“This also demonstrates that they were able to adapt their response level to obtain the reward they wanted.

“Our study highlights experimentally the existence of complex cognitive processes in ungulates such as horses, which probably involve the subject forming a conscious mental representation of the consequence of its actions, including the causal status of these actions.”

The findings, they said, were also of interest when it came to optimizing and tailoring the training and living conditions of horses.

“In particular, a common practice in the field consists in giving the same kind of food to reward the animal during training, but also at any other moment, for instance to improve the relationship with the animal.

“The fact that the horse is sensitive to the contingency between its action and the associated reward suggests that this practice is inappropriate and tends to demonstrate how important it is to use a specific kind of food reward for a desired action and never to give this food under other circumstances.

“This is especially true for unfearful horses.

“Moreover, the predisposition of the most fearful horses to switch more easily to a habit-type response certainly has an incidence on the capacity of domestic horses to adapt to their conditions of training and captivity.

“On the one hand, this predisposition may be an asset for training since riders seek horses that respond to their aids more rapidly and automatically, and a horse that has developed habits may do this independently of reinforcement.”

This, they said, may contribute to explaining why fearful horses were popular with experienced riders despite being more complicated to ride.

“On the other hand, this propensity for habit processes may represent a risk factor for the most fearful subjects to develop psychopathologies, in particular stereotypies of animals kept in captivity, such as horses.”

The study team comprises Lansade, Alain Marchand, Etienne Coutureau, Cyrielle Ballé, Floriane Polli, and Ludovic Calandreau. The researchers are affiliated with a range of French institutions, including the Université de Tours, the Université de Bordeaux, and the French National Institute for Agricultural Research.

Lansade L, Marchand AR, Coutureau E, Ballé C, Polli F, Calandreau L (2017) Personality and predisposition to form habit behaviours during instrumental conditioning in horses (Equus caballus). PLoS ONE 12(2): e0171010. doi:10.1371/journal.pone.0171010

The study, published under a Creative Commons License, can be read here.  

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