Measuring emotional contagion in Horse-Human interactions: A systematic scoping review of methods and outcomes.

Overview

• This study systematically reviewed how emotional contagion between horses and humans is measured, examining the methods used and the outcomes reported in existing research.
• The goal was to identify common behavioral and physiological indicators and to assess the strengths and limitations of these approaches.

Introduction to Emotional Contagion in Horse-Human Interactions

• Emotional contagion refers to the phenomenon where emotions are transferred from one individual to another, impacting behavior and physiological states.
• In the context of horses and humans, emotional contagion is crucial because it influences:
• Animal welfare
• Training effectiveness
• Therapeutic outcomes for humans
• Despite its importance, there is currently no standardized or consistent method to measure emotional contagion between horses and humans.

Research Objectives

• To systematically identify the methods used to assess emotional contagion in horse-human interactions.
• To summarize the behavioral and physiological outcomes reported in the literature.

Methods

• The researchers conducted a systematic literature search in multiple databases: Google Scholar, Web of Science, Scopus, PubMed, and Science Direct.
• The search was conducted up to March 2024.
• Inclusion criteria:
• Peer-reviewed studies that assessed emotional transfer between horses and humans.
• Studies that used behavioral and/or physiological measures.
• Exclusion criteria:
• Studies outside the emotional contagion scope.
• From 486 screened records, 104 studies met criteria and were included for analysis.

Behavioral Measures

• Behavioral indicators were the most commonly used methods to assess emotional contagion.
• Key behavioral measures included:
• Body language (used in 73.1% of studies) – such as posture, movement, and proximity.
• Facial expressions – which can convey emotional states like relaxation or stress.
• Vocalizations – sounds made by horses or humans related to emotional states (e.g., neighs, whinnies, or human tone).

Physiological Measures

• Physiological indicators provided objective measures of emotional states.
• Mostly used physiological measures were:
• Heart rate (49% of studies) – increased or decreased rates can reflect emotional arousal.
• Heart rate variability (HRV) (30.8%) – variability in heart beats indicating autonomic nervous system balance.
• Cortisol concentration – a hormonal marker of stress, less frequently used.

Combined Behavioral and Physiological Approaches

• Studies combining both types of measures tended to yield more comprehensive insights.
• The most robust findings came from pairing body language with heart rate or HRV readings.
• This multimodal assessment helps cross-validate emotional contagion indicators, increasing reliability.

Limitations and Challenges

• There were significant methodological inconsistencies across studies, such as differing protocols, sample sizes, and analysis techniques.
• Lack of standardized frameworks limits the ability to compare results across different studies reliably.
• Variability in how emotions are defined and operationalized adds complexity to measuring emotional contagion.

Conclusions and Recommendations

• A combined approach using both behavioral and physiological measures is recommended for a more thorough assessment of emotional contagion in horse-human interactions.
• For future advancements, the study highlights the need for:
• Development of standardized measurement frameworks to enable comparable and consistent results.
• Interdisciplinary collaboration involving ethologists, physiologists, psychologists, and technology experts.
• Integration of emerging technologies such as artificial intelligence for data analysis and wearable devices that allow real-time monitoring.
• Such improvements would enhance the reliability of measurements and support practices that improve welfare and interaction quality between horses and humans.

Implications

• Better measurement tools can inform evidence-based training and therapeutic protocols.
• Improved understanding of emotional contagion can strengthen bonds and communication between horses and humans.
• Enhanced welfare strategies can be developed, leading to healthier, more positive horse-human relationships.