Effects of human stress on horse behavior and interaction quality

Human-horse interaction can be influenced by the emotional and physiological state of humans, as horses are highly sensitive to human stress. Understanding these effects is essential for improving outcomes in equine-assisted activities. This study examined how human stress impacts horse behavior and interaction quality. Seven humans and seven horses participated in a crossover design experiment in which participants viewed either stressful or relaxed video stimuli prior to interacting with horses. Electroencephalography (EEG), heart rate variability (HRV), and salivary cortisol was collected to assess human physiological responses, while the Human-Animal Interaction Scale (HAIS) and an ethogram evaluated interaction quality and horse behaviors. Stressful stimuli significantly increased beta and high-beta activity and altered HRV indices, indicated by increased low-frequency power and decreased high-frequency power. HAIS scores were lower under stress conditions, reflecting reduced interaction quality. Horses exhibited more pushing behavior and less lip-licking when handlers were stressed, although task completion time did not differ between conditions. These results demonstrated that human stress negatively influences both physiological states and behavioral outcomes within human-horse interactions. Therefore, managing emotional states and stress levels may enhance interaction quality and effectiveness in equine-assisted programs.