Stress affects instrumental learning based on positive or negative reinforcement in interaction with personality in domestic horses.
Authors: Valenchon Mathilde, Lévy Frédéric, Moussu Chantal, Lansade Léa
Journal: PloS one
Summary
# Editorial Summary Researchers at INRA explored how acute stress influences a horse's ability to learn a simple discrimination task—entering the correct compartment in response to a visual cue—when trained using either negative or positive reinforcement, with particular attention to individual personality differences. Sixty horses were divided into four groups (n=15 each) and trained under conditions that either included or excluded unrelated stressors (novel, sudden stimuli), allowing the researchers to isolate the effects of stress from the learning protocol itself. When stressors were absent, horses learned equally well regardless of reinforcement type; however, exposure to environmental stressors substantially impaired learning performance overall, though this deficit was significantly smaller in horses trained with negative reinforcement—a finding suggesting that task-related stress may paradoxically help focus attention during learning. Personality traits interacted markedly with both stress conditions and reinforcement type: highly fearful horses performed relatively well under negative reinforcement in calm conditions but deteriorated substantially when stressors were present, whereas under positive reinforcement, fearful horses consistently underperformed regardless of the stress environment. For equine professionals, these findings indicate that training method choice has meaningful implications beyond simple learning efficacy—negative reinforcement may offer particular advantages for naturally anxious horses in unpredictable environments, whilst positive reinforcement-based programmes may prove more resilient for fearful individuals in variable conditions, though matching training methodology to individual temperament warrants serious consideration.
Read the full abstract on PubMed
Practical Takeaways
- •Negative reinforcement (task-related stress) may focus attention and partially buffer against unrelated environmental stressors during training, but this advantage disappears for anxious horses when stressors are present
- •Positive reinforcement is more reliable for fearful horses as it maintains consistent learning performance across different stress environments
- •Consider individual personality/temperament when selecting training methods—one approach does not suit all horses equally, especially under stressful conditions
Key Findings
- •In absence of stressors, learning performance did not differ between negative and positive reinforcement groups
- •Extrinsic stressors (novel/sudden stimuli) impaired learning performance, but this deficit was smaller with negative reinforcement
- •Fearful horses performed best with negative reinforcement in low-stress conditions but worst in high-stress conditions
- •Fearful horses consistently underperformed with positive reinforcement regardless of stress presence