Object habituation in horses: The effect of voluntary vs. negatively reinforced approach to frightening stimuli

Object habituation in horses: The effect of voluntary vs. negatively reinforced approach to frightening stimuli:

Summary

Reasons for performing the study: The ability of horses to habituate to novel objects influences safety in the horse-human relationship. However, the effectiveness of different habituation techniques has not been investigated in detail.

Objectives: (1) To investigate whether horses show increased stress responses when negatively reinforced to approach novel objects, compared to horses that are allowed to voluntarily explore the objects. (2) To investigate whether negatively reinforced approach facilitates object habituation.

Methods: Twenty-two 2–3 year old Danish Warmblood geldings were included. Half of the horses (NR group) were negatively reinforced by a familiar human handler to approach a collection of novel objects in a test arena. The other half of the horses were individually released in the arena and were free to explore the objects (VOL group). On the next day, the horses were exposed to the objects again without a human to investigate the rate of habituation. Behavioural and heart rate responses were recorded.

Results: All VOL horses initially avoided the unknown objects, whereas the handler was able to get all NR horses to approach and stand next to the objects within the first 2 min session. NR horses had a significantly longer duration of alertness and a higher max heart rate in the first session. On the next day, however, NR 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.

Conclusion: Negatively reinforced approach to novel objects increases stress responses during the initial exposure, but facilitates habituation in young horses.

Potential relevance: Although 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. Further experiments should aim to investigate differences in stimulus intensity.

© 2012 EVJ Ltd