Asymmetry of behavioral responses to a human approach in young naive vs. trained horses.

This study explores how training impacts a horse’s reaction to a human approach, noting that untrained young horses show asymmetrical responses – negative when approached from the left and positive from the right. However, this behavioural bias tends to even out with training and age.

Objective of the Research

• The primary aim of this study was to examine the effect of training on the lateralized (side-specific) responses of young horses to a human approaching them.

Research Findings

• In one-year-old untrained horses, researchers observed asymmetrical reactions: horses tended to react negatively (e.g., escape, threats) when approached from the left side. Conversely, when approached from the right side, these horses displayed more positive behaviors.
• In contrast, two-year-old trained horses exhibited equanimous responses to human approach, reacting positively irrespective of the side of the approach. This suggests that training can significantly moderate horses’ uneven reactions.

Links to Prior Studies and Conclusions

• The results of this study agree with previous research advocating a correlation between emotionality (emotional response) and laterality (preference for one side).
• Through the observed behaviors, the study affirms the role of the left hemisphere of the brain in processing stimuli that are novel or negative in nature. In horses, this often manifests as a tendency to react less favorably when approached from the left side.
• Crucially, the study’s data underscores the significant influence that work and training exert on the lateralization of reactions in horses, helping mitigate their negative responses over time.