This article has been updated with additional information from the original published in Oct. 2023.


There seems to be a growing social media chatter about research conducted at the Heart Math Institute on shared electromagnetic fields between horses and humans, which purportedly explain why we feel good around horses. Intrigued about the science behind the connectivity, peacefulness, and overall exceptional feeling that horse enthusiasts, including myself, consistently experience around horses I was eager to dig in.

The Heart Math claim

The Heart Math Institute claims that scientific evidence conducted by Dr. Ann Baldwin and Dr. Ellen Gehrke indicates that horses can sense, and respond in kind, to the emotional state of humans – not only when we are afraid, but also when we are feeling positive emotions such as appreciation. Apparently, they do so with an electromagnetic field, much larger than our own, projected by their heart which surrounds and influences our own heart rhythms in a positive way. Further, horses are said to possess a coherent heart rhythm (indicative of a calm state of well-being) which can further impact our mental state and explains why horses make us feel good.

A word about Heart Rate Variability (HRV)

Heart rhythm is measured through electrocardiography (ECG) recordings to provide a reading of Heart Rate Variability or HRV. Unlike Heart Rate (HR), which measures the number of heart beats per minute, HRV measures the changes in the intervals between consecutive heart beats. The fluctuations of a healthy heart are complex, and variability means the heart is flexibly coping with uncertain and shifting environmental and psychological challenges. In its most simplistic terms, a high HRV reading generally suggests the heart is adjusting quickly to changing circumstances and indicates good health, active coping, and well-being. HRV has been used to reliably assess stress reactions, behavioural dysfunction, and emotional states in humans, horses, and other farm and companion animals (e.g. Rietmann et al., 2004).

Heart Math science

My first sleuthing task was to find the original research by doctors Baldwin and Gerhke cited by the Heart Math Institute. In the first study Ellen Gehrke monitored her horse’s and her own HRV while sitting in a paddock with her horse and thinking thoughts of love and appreciation for him (2011). Her HRV showed a coherent pattern (indicative of a positive state); soon, her horse Tonopah’s HRV also shifted to a more coherent pattern.

The Heart Math Institute’s interpretation was that “Tonapah was able to sense and respond to the emotional information carried by the energetic field of Ellen’s heart” ( First, it is a stretch to call this unpublished report a “study”. I would call it a curious researcher hanging out with her horse thinking nice things. Second, the findings support a human influencing a horse’s psychological state, rather than the other way around, which runs counter to the Heart Math claim that horses’ greater electromagnetic heart fields positively influence our own. Finally, the interpretation goes well beyond the data. Clearly, we cannot glean anything about Tonopah’s ability, or lack thereof, to read emotional information generated by Ellen’s energetic heart field from these HRV readings.

The Heart Math Institute maintains that this result was “replicated successfully with several different human horse pairs” ( After an extensive search, I found five published studies by these authors. A 2012 study by Baldwin and Gehrke , looked at HRV in nine horses used for equine facilitated therapy to see how the horses were coping with the potential stress of their occupation. The study did not explore the riders’ HRV or any potential synchronization between horse and rider. Gehrke’s 2016 study explored horse-to-human heart connectivity more directly with a sample size of two (one coach/rider dyad, and one coach/rider/horse triad) – in effect, a sample size of one, as only the triad included a horse. Although the coach’s HRV increased during the sessions, and both coaches and riders experienced positive emotions when the horse was present, any comparisons about synchronized heart fields was not possible as there were technical issues and the rider and horse HRV recordings were not readable. The authors claim that “positive emotions in humans reflected in healthy HRV patterns was enhanced in the presence of horses during triad-coaching sessions”, but their data (HRV readings from one coach) cannot support this interpretation.

There were three studies by Ann Baldwin and colleagues (2018, 2021, and 2023). In the 2018 study, 24 participants interacted with a horse or with a human researcher (that served as the control condition) while measuring HR and HRV. The interaction, the “Con Su Permiso (With Your Permission)” exercise had participants approach the horse (or the human), say “hello”, rub their palms together to heighten sensation, and move toward their subject (horse or human) when invited (the subject looks their way or approaches). Holding their hands close but not touching, they scanned the subject’s body with their palms, thanked them, and noted any sensations in their hands. Contrary to predictions, HRV did not increase significantly in the interaction with horses, but did do so in the control condition with the human subject. As for synchronicity, seven of the 24 participants displayed the Very Low Frequency (VFL) peaks similar to their horses and indicative of a calm state.

In her 2021 study, Baldwin had 24 residents of a senior’s care facility engage in 10-minute stroking sessions with one of three resident horses – Prissy, Joe, and Herman. To choose which horse they would work with, participants were directed to breathe slowly and deeply while sending feelings of love and appreciation (heart beams) toward the three horses:

“Please focus your attention on the area of your heart. As you breathe in, imagine the breath going into your heart. As you breathe out, imagine the breath is leaving your heart. Count slowly to five as you breathe in and slowly to five as you breathe out. One and two and three and four and five. Now direct your breath heart beam towards the horses and sense/feel which horse’s heart is calling to your heart. As you breathe in, imagine the breath is coming from THAT horse’s heart to your heart. As you breathe out, imagine your breath is going from YOUR heart to your chosen horse’s heart.” (breath heart beam)

The researchers note that participants generally chose the horse that was showing the most interest in them (look, head movement, approach, etc.) and who was sending them “heart breath beams.”


A girl hugging a horse.

Companion animals, including horses, have been shown to reduce loneliness and increase affiliation, social engagement, responsiveness, self-esteem and overall psychological well-being. (zzzdim –


Baldwin hypothesized that the seniors’ HR and HRV would increase during stroking, indicating increased arousal (HR) and increased well-being (HRV), and that HRV would shift toward the Very Low Frequency (VFL) intervals characteristic of the horses, also indicative of calm and well-being. Although HR did increase, contrary to their hypothesis, participants’ HRV did not significantly shift towards the Very Low Frequency range of their horse partner.

Sixteen out of 26 participants showed HRV frequencies that matched, or almost matched, those of their horses in at least two of the four sessions. Seniors showed more engagement with the facilitator during the sessions and reported positive feelings of connection to the horse at the study’s conclusion. However, the authors admit that more research is necessary to indicate that horses and humans connect and communicate through HRV synchronization (Baldwin, 2021).

In Baldwin and colleague’s 2023 study they compared 24 seniors’ HRV while grooming a real horse or a plush simulation horse. Interestingly, HRV increased with both the real and simulation horse, suggesting that grooming makes us feel good even when it is not a real horse. However, in support of their hypothesis, HRV shifted toward the Very Low Frequency range (VLF – that is the calm place where we’d like to be more often and where horses seem to hang out) with the real horse but not with the simulation horse. Additionally, in 10 out of the 24 human/horse pairs, matching HRV frequencies occurred during the interaction, which supports the concept that HRV oscillations can become synchronous between horse and human during mindful grooming.

There are also two unpublished dissertations cited on the Heart Math Institute site (Cicėnaitė et al., 2016; Dampsey, 2017). The dissertations have yet to been published, nor was I able to find any other publications about horse and human hearts from the primary or secondary authors.

Science is continually self-correcting … without peer-review, these papers carry as much weight as any opinion we might encounter from anyone’s social media rantings.

There are good reasons why scientists do not cite unpublished research as support for a particular claim. When a study is published, it means that manuscript submissions have undergone intense scrutiny from several scientists who are regarded as experts in that field, and who collectively decide whether the methodology, the interpretation and the overall science are sound. Many more papers are rejected than accepted, and accepted papers are nearly always sent back for revisions. This is an integral part of the scientific process and how we can feel assured that published scientific findings accurately represent the knowledge in the field at the time. Is it truth? No. Subsequent research could uncover new discoveries that question or refute what came before, and in this way, science is continually self-correcting. Without peer-review, these papers carry as much weight as any opinion we might encounter from anyone’s social media rantings.

The Heart Math studies, along with a substantial and convincing body of research, indicate that people do better when they interact with horses – they get excited, find more meaning and purpose in their lives, report fewer psychological problems and experience greater quality of life during the time of the study (e.g., Dableko-Schoeny et al., 2014; Lee et al., 2019; Romaniuk et al., 2018).

Baldwin’s findings also show that horses exhibit VLF associated with a calm state, and in some cases these frequencies may increase in the human heart when they spend time engaging with horses. It is certainly possible that other animals may also raise VLF in humans, but to my knowledge there is yet no published evidence exploring this question. Companion animals have been shown to reduce loneliness and increase affiliation, social engagement, responsiveness, self-esteem and overall psychological well-being (e.g. McCardle et al, 2011). Physiological benefits include decreased risk for cardiovascular disease, shorter recovery time after heart attack, and improved overall physical health (e.g. Allen, 1991; Friedman et al, 2000). Even watching an aquarium of fish facilitates relaxation, lowers blood pressure, and reduces stress responses when performing the stressful task of reading aloud. (Katcher et al.,1983). Participants having to complete the anxiety provoking task of solving math problems experience the least stress in the presence of the non-judgmental support offered by their dog, and the highest when in the presence of a close friend (Allen, 1991).

What do we know about Heart Synchronicity?

Casting a wider net, I looked to see what other researchers had found about the potential transmission of positive and/or negative emotions between horses and humans, and HR or HRV synchronicity. There is some evidence that our emotional state (particularly anxiety) can be transmitted to our horses, but even this seemingly obvious association is not consistent across studies.

For example, an ingenious study by Linda Keeling and colleagues (2009) had non-professional horse riders lead or ride a horse four times between two designated points. They were warned, just before the final pass, that a research assistant would be opening an umbrella. Not surprisingly, participants’ HR lowered with each successive pass, but spiked when they learned about the umbrella. Interestingly, horses, who were clearly not privy to this information, experienced the same HR spike, even though no umbrella ever made an appearance.

There is some evidence that our emotional state (particularly anxiety) can be transmitted to our horses, but even this seemingly obvious association is not consistent across studies.

Mareike von Lewinski and her group, however, did not see a similar rider-to-horse anxiety transmission in high-performance dressage rider-horse pairs performing at an actual horse show and an identical dress-rehearsal without spectators. Although riders’ stress responses rose significantly in the actual horse show vs. the private dress-rehearsal, their horses’ stress responses did not change. Horses found all performance equally stressful, and unlike the anticipated but fictitious popping umbrella, did not seem to be influenced by their riders’ rising anxiety (Mareike von Lewinski et al., 2013)

Other research by University of Guelph researcher Katrina Merkies offers yet another piece to this puzzle indicating that horses, free to interact with blindfolded human participants, exhibited slower and calmer behaviour (lowered HR) when interacting with a person who was physically stressed (an elevated HR due to exercise) or psychologically stressed (elevated HR due to a fear of horses – where on earth did they find these volunteers??), than they were with a calm person with a normal HR (Merkies et al., 2014). Further work by this group found that horses were most stressed when alone, calmer in the presence of an inexperienced horse person, but more attentive with an experienced person, and, unlike many humans, exhibited no mental health prejudices, reacting just as calmly to participants suffering from PTSD as they did to those without (Merkies et al., 2018).

Chiara Scopa and colleagues found that horses appeared calmer and had higher HRV ratings (i.e. more relaxed) when groomed by familiar humans than unfamiliar humans (2020). Similarly, Jo Hockenhull found that horses became calmer when led through a short obstacle course when the handler was familiar to them, but that familiarity provided no such advantage for their human handlers who were more stressed handling their own horse than an unfamiliar one (Hockenhull et al., 2016).

As for human/horse heart synchronicity, Hockenhull found that only six of the 34 pairings showed any correlation between horse-and-handler heart rates. She concludes that the horse/human HR relationship is not straightforward, and many intangible, difficult to measure, factors contribute to this inconsistent picture.

If not heart, then what?

I know I am a member of the most privileged group in the world to have horses in my life. They keep me fit, allow me to connect with nature, and they feed my soul. Anyone reading this article knows there is something profound and unique about this relationship that is different than a relationship with a dog or a cat or even a human. As yet, we still do not know why. Merging electromagnetic heart fields offers a potential explanation worthy of further empirical testing. To date, we do not have the evidence to say that this is so.

As a theory, I feel more connection with the writings of Boris Levinson (1984), an early pioneer of animal-assisted interventions. He proposed that in our increasingly technological and industrialized world we have become alienated from nature and impoverished as a result (Note: his writings came well before smart phones and social media!). He maintains that we can restore a healing connection with our own unconscious animal nature by fostering a relationship with a companion animal who sits on an intermediary line between the wild animal in nature and human. If this is so, perhaps horses take us further into this realm because their proximity to nature and to the wild is closer still, the connection more tenuous, their admiration that much harder won, and their gift to us so immense.