Object habituation in horses: the effect of voluntary versus negatively reinforced approach to frightening stimuli.

This research investigates the ability of horses to become accustomed to new objects, and specifically how different techniques may influence this process. The study looks at whether a negatively reinforced approach, where horses are persuaded by a familiar human handler to engage with new objects, leads to heightened stress compared to allowing horses to explore these objects voluntarily. Findings show that while the negatively reinforced approach may cause initial stress, it ultimately facilitates quicker habituation.

Research Objectives

• The study aimed to examine if horses that were negatively reinforced to interact with new objects showed higher stress levels compared to those that were allowed to explore these objects freely.
• Another objective was to see if the negatively reinforced approach helped with object habituation, meaning the process by which the horse grows accustomed to the presence of the new object and thus stops regarding it as a threat.

Methods

• 22 young male Danish Warmblood horses were divided into two groups for the study. In one group, a familiar human handler negatively reinforced the horses to approach and interact with a set of new objects in the test arena.
• The horses in the second group were individually let loose in the arena and allowed to explore the objects voluntarily.
• The following day both groups of horses were exposed to the objects again, this time without a human present, in order to assess the rate of habituation.
• The researchers recorded the behaviour and heart-rate responses of the horses as indicators of stress.

Results

• Initially, the voluntarily exploring horses avoided the unfamiliar objects while the handler persuaded all the negatively reinforced horses to approach and even stand next to the objects in the first two-minute session.
• In contrast with the voluntarily exploring horses, the negatively reinforced horses had a significantly longer duration of alertness and a higher maximum heart rate in the first session.
• On the second day, the negatively reinforced horses spent less time inspecting the objects and approached a feed container placed near the objects faster. This behaviour suggests an increased level of habituation.

Conclusions

• While a negatively reinforced approach to new objects increased stress responses during the initial exposure, it ultimately encouraged faster habituation in young horses.
• Although the negatively reinforced approach seems beneficial for habituation, careful management is required due to the increased initial stress responses in the horses, which may be a safety risk.
• Future research should look into differences in stimulus intensity, meaning how varying the size, shape or type of the new object might affect the horse’s habituation process.