Evidence for Right-Sided Horses Being More Optimistic than Left-Sided Horses.
Authors: Marr Isabell, Farmer Kate, Krüger Konstanze
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Cognitive bias testing—measuring whether horses interpret ambiguous situations optimistically or pessimistically—offers valuable insights into emotional state and welfare, but conventional judgment bias protocols are time-consuming and require careful standardisation. Marr and colleagues investigated whether motor laterality (forelimb preference) could serve as a quicker proxy for cognitive bias in 17 horses trained to discriminate between boxes placed in positive and negative locations, then tested their responses when the box was positioned ambiguously between these trained sites. Horses demonstrating right forelimb preference when initiating movement from standstill approached the ambiguous box significantly faster than left-preferring animals (p < 0.01), indicating a more optimistic interpretative bias. This finding suggests a practical shortcut: assessing which forelimb a horse preferentially uses to move off could rapidly flag cognitive bias tendencies without formal judgment testing, potentially identifying welfare concerns or training readiness more efficiently in routine practice. For farriers and handlers, observing laterality preferences during everyday movement may provide meaningful behavioural insights, whilst the correlation between brain hemisphere dominance and emotional outlook reinforces the importance of considering individual variation in horse temperament and decision-making.
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Practical Takeaways
- •Motor laterality (which forelimb a horse leads with) may offer a practical, quick screening tool for assessing individual horses' optimism or pessimism without formal behavioral testing
- •Right-preferring horses may be more likely to approach novel situations positively; this could inform handling strategies and stress assessment on individual horses
- •Understanding a horse's cognitive bias through laterality assessment could improve welfare monitoring and management decisions in equine facilities
Key Findings
- •Horses with right forelimb preference approached an ambiguous box with shorter latency than left-forelimb preferring horses (p < 0.01)
- •Right-sided motor laterality in horses is associated with positive cognitive bias (optimism)
- •Motor laterality may serve as a quicker and more repeatable proxy for conventional judgment bias testing in horses