How to quantify negative reinforcement training

31 Aug 2015

The majority of horses are trained using negative reinforcement methods; pressure is applied and removed when the horse responds correctly. Scientists from Denmark and the UK set out to quantify horses’ responses to negative reinforcement training, by measuring the amount of pressure it took horses to respond to a task. Twenty-four Icelandic horses were subject to a test, whereby pressure was applied to an exact spot on their hindquarter with an algometer. An algometer is an instrument that measures force. Once the horses took at least one step sideways with their hind end away from the pressure, the pressure was removed.

An algometer measures the amount of pressure applied – source Topcat Metrology 

As expected, the average amount of pressure required to move the horses’ sideways decreased over the three days of the trail. The greatest decrease occurred between day one and day two and a lesser increase occurred between day two and day three. The horses were subject to ten trials on each side on the first day, seven on the second day and five on the last day. Interestingly, the learning did not seems to translate from one side to another, when the researchers switched sides, the horses still tended to start off needing just as much pressure on the second side. Whether the left or right side was done first was randomly chosen.

Another curious result was that the right side required on average 1.4 times more force than the left side. The scientists are unsure why this is, they have hypothesised that perhaps is could be because the test was undertaken by a right handed person.

All of the horses that participated in the study were three-year-olds with basic handling. Twelve of the twenty-four horses of the horses had received some ground work training in an earlier study, this training did not involve yielding the hind end exclusively but it did involve yielding to the side with the entire body. The horses that had taken part in this earlier study required on average 40% less pressure to respond, suggesting that there was some transfer of behavioural response or that these horses were more coordinated due to the previous training.

The pressure required to make the horses move ranged from 0.04 Newtons to 30 plus Newtons. 30 Newtons is equivalent to approximately 3.06kg. The researchers stated that future studies should use algometer that measures in excess of 30 Newtons as that was the limit of the instrument used in this study and some animals required an excess of this force (in these cases the researcher had to apply pressure with two hands instead of one.)

There was no difference between mares and geldings. It is interesting to measure and quantify the amount of force it requires to get a horse to respond as it can measure an individual’s aptitude to this type of learning, some animals may be more sensitive than others. Potentially an algometer is a useful teaching tool to help people slow down and consciously see the amount of force they are using, so that they ask in the lightest possible way in the beginning and consistently increase the pressure.

Reference
Ahrendt, L. P., Labouriau, R., Malmkvist, J., Nicol, C. J., & Christensen, J. W. (2015). Development of a standard test to assess negative reinforcement learning in horses. Applied Animal Behaviour Science.

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