A Danish researcher is urging horse owners to use caution when using negative reinforcement to get horses used to unfamiliar objects.
Janne Winther Christensen, from the Department of Animal Science at Aarhus University in Tjele, carried out her research on habituation using 22 two- to three-year-old Danish warmblood geldings.
Christensen said that the ability of horses to get used to novel objects influenced safety in the horse–human relationship. However, the effectiveness of different techniques to achieve this aim had not been investigated in detail, she noted.
Christensen set about investigating whether horses showed increased stress responses when negatively reinforced to approach novel objects, compared with horses allowed to voluntarily explore the objects, and whether a negatively reinforced approach aided object habituation.
Half of the horses were negatively reinforced by a familiar human handler to approach a collection of novel objects in a test arena. The other half were individually released in the arena and were free to explore the objects voluntarily.
The next day, the horses were exposed to the objects again without a human handler, to investigate the rate of habituation.
Behavioural and heart-rate responses were recorded.
All horses in the group that was allowed to voluntarily investigate the objects the day before initially avoided the unknown objects, whereas the handler was able to get all negatively reinforced horses to approach and stand next to the objects within the first two-minute session.
The negatively reinforced horses had a significantly longer duration of alertness and a higher maximum heart rate in the first session.
On the next day, however, the negatively reinforced horses spent significantly less time investigating the objects and had a shorter latency to approach a feed container, placed next to the objects, indicating increased habituation.
Christensen found that a negatively reinforced approach to novel objects increased stress responses during the initial exposure, but aided habituation in young horses.
“Although a negatively reinforced approach appears beneficial for habituation, the procedure should be carefully managed due to increased stress responses in the horse, which may constitute a safety risk,” she said.
“Further experiments should aim to investigate differences in stimulus intensity.”
Her study, entitled “Object habituation in horses: The effect of voluntary versus negatively reinforced approach to frightening stimuli”, has been published in the Equine Veterinary Journal.
The abstract can be found online here.
Christensen, J. W. (2013), Object habituation in horses: The effect of voluntary versus negatively reinforced approach to frightening stimuli. Equine Veterinary Journal, 45: 298–301. doi: 10.1111/j.2042-3306.2012.00629.x