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Scientific reports2026; 16(1); 27658; doi: 10.1038/s41598-026-65168-2

Mutual wellbeing in an equine-assisted intervention: experimental evidence for the two-way hypothesis and the importance of interaction method.

Abstract: Rising rates of mental health disorders have increased demand for scalable, non-pharmacological interventions. Interactions with animals can improve emotional wellbeing across diverse populations, yet the mechanisms responsible for these benefits remain poorly understood. Most research focuses on human outcomes while treating the animal as a passive component of the interaction, despite human-animal interactions being inherently reciprocal. We therefore propose the Two-Way Hypothesis, which predicts that human behavior shapes animal behavior, which in turn contributes to variation in human emotional outcomes. We experimentally tested this hypothesis in 61 adolescents who participated in standardized interactions with miniature equines (horses and donkeys) under manipulated tactile conditions (petting or scratching). Emotional state was assessed before and after the interaction, and equine behavioral responses were recorded during the interaction. Scratching increased affiliative lip-wiggling behavior and reduced voluntary disengagement (walking away) compared with petting. In turn, observing lip wiggling predicted greater reductions in loneliness, whereas observing walking away predicted greater reductions in sadness. These findings provide experimental support for the Two-Way Hypothesis, demonstrating that human interaction style can influence animal behavior and that this behavioral variation corresponds to differences in human emotional outcomes. This framework provides a tractable basis for investigating the mechanisms underlying animal-assisted interventions.
© 2026. The Author(s).
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Publication Date: 2026-09-15 PubMed ID: 42744875PubMed Central: PMC13578761DOI: 10.1038/s41598-026-65168-2Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study experimentally tested how interactions between adolescents and miniature equines (horses and donkeys) influence both the animals’ behavior and the humans’ emotional wellbeing.
  • The research supports the idea that human-animal interactions are reciprocal, where the way humans interact with animals affects animal responses, which in turn impacts human emotions.

Background and Motivation

  • Mental health disorders are increasing, creating a need for scalable, non-drug-based therapeutic interventions.
  • Animal-assisted interventions have shown promise in improving emotional wellbeing but the underlying mechanisms are not well understood.
  • Most existing research treats animals as passive participants rather than active contributors in interactions.
  • The researchers proposed the “Two-Way Hypothesis,” which states:
    • Human behavior affects animal behavior during interactions.
    • Animal behavior then influences human emotional outcomes.

Study Design and Methods

  • Participants: 61 adolescents took part in the study.
  • Interaction Setup:
    • Adolescents interacted with miniature equines, including both horses and donkeys.
    • Two different tactile methods were used: petting versus scratching.
    • The interactions were standardized and controlled experimentally.
  • Measurements:
    • Emotional state of participants was assessed before and after the animal interaction to measure changes.
    • Equine behaviors during the interaction were observed and recorded.

Key Findings

  • Differences in animal behavior based on interaction type:
    • Scratching induced more affiliative behaviors in the equines, especially lip-wiggling, which is a positive, social signal.
    • Scratching also caused less voluntary disengagement — the equines were less likely to walk away compared to petting.
  • Correlations between equine behavior and human emotional changes:
    • When adolescents observed lip-wiggling, they experienced greater reductions in feelings of loneliness.
    • When equines walked away (disengaged), this predicted greater reductions in sadness among the adolescents.
    • This indicates that different animal behavioral responses can impact different aspects of human emotional wellbeing.

Interpretation and Implications

  • The study provides experimental evidence supporting the Two-Way Hypothesis, confirming that:
    • Human interaction styles (petting vs. scratching) deliberately influence animal responses.
    • These animal responses then correspond with measurable changes in human emotional states.
  • Findings emphasize the importance of considering animal behavior as an active part of therapeutic interactions, not just a passive element.
  • This bi-directional framework suggests that tailoring animal interaction methods could optimize emotional benefits for humans receiving animal-assisted interventions.
  • Helps to provide a biological and behavioral mechanism basis for improving and scaling non-pharmacological mental health interventions involving animals.

Conclusion

  • The mutual wellbeing of humans and animals during interactions can be influenced by how humans engage with animals.
  • The Two-Way Hypothesis offers a promising model for studying and enhancing animal-assisted interventions, aiming at improving adolescent emotional health.
  • Future research can build on this framework to understand more nuanced mechanisms and to develop best practices for therapeutic animal interactions.

Cite This Article

APA
Short CJM, Calisi RM. (2026). Mutual wellbeing in an equine-assisted intervention: experimental evidence for the two-way hypothesis and the importance of interaction method. Sci Rep, 16(1), 27658. https://doi.org/10.1038/s41598-026-65168-2

Publication

Scientific reports
ISSN: 2045-2322
NlmUniqueID: 101563288
Country: England
Language: English
Volume: 16
Issue: 1
PII: 27658

Researcher Affiliations

Short, Claire J M
  • Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, USA.
Calisi, Rebecca M
  • Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, USA. rmcalisi@ucdavis.edu.

MeSH Terms

  • Animals
  • Humans
  • Horses
  • Female
  • Male
  • Adolescent
  • Emotions
  • Behavior, Animal
  • Equine-Assisted Therapy / methods
  • Human-Animal Bond
  • Human-Animal Interaction

Conflict of Interest Statement

Declarations. Competing interests: The authors declare no competing interests.

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