A new study suggests that our hearts slow down when we make visual mistakes, providing evidence that our bodies react to perceptual errors even before we realize we have made them. Published in Biological Psychology, the research shows that conscious perception emerges from a constant dialogue between the brain and the body.
Historically, cognitive neuroscience has focused heavily on the brain to understand how we perceive the world. However, the brain is in constant communication with the peripheral nervous system, which is the network of nerves connecting the brain and spinal cord to the rest of the body. Scientists wanted to understand how this body-brain connection influences conscious perception.
“My main motivation (and for my colleagues) was to better understand perceptual consciousness — a concept with many branches and no single, universally accepted definition,” said study author María I. Cobos Martín, a cognitive neuroscience researcher at the University of Granada.
“When we try to explain how we perceive the world and how a conscious experience is formed, we often think almost exclusively in terms of brain activity. But humans are not ‘just a brain. There is growing evidence showing that the brain is in constant communication with the organs of the body, and one of them is the heart. This raises an important question: if our heartbeat continuously sends signals to the brain and the brain to the heart, wouldn’t it be reasonable to think that the way the heart beats might contribute to shaping conscious perception?”
“Ultimately, the heartbeat is the way the heart sends messages to the brain. With this study, we wanted to explore precisely how the heart (with brain signals) relates to the moments when perception is accurate — and the moments when it fails. Understanding this dialogue is essential for seeing consciousness not as a purely cortical process, but as something that emerges from the whole body.”
To test this, the researchers recruited 30 healthy undergraduate students, though the final data analysis included 24 to 26 participants due to equipment glitches and excessive eye movements. The team used an eye tracking camera to monitor where participants were looking and an electrocardiogram to measure their heartbeats.
During the experiment, participants looked at a computer screen and were briefly shown a string of letters. The target letter was an “L” alongside a distractor letter “O,” and both letters were always presented in different colors. Participants were asked to identify the color of the target letter.
The researchers adjusted the difficulty of the task for each person so that they would answer correctly about 70 percent of the time. The remaining 30 percent of the time, participants were expected to make a specific type of mistake called a perceptual illusion. This happens when the brain incorrectly blends features, such as seeing the target letter but assigning it the color of the distractor letter.
To test the effect of alertness, the scientists also played a brief, loud tone through headphones on half of the trials. At the end of the experiment, they introduced an unexpected change by sometimes making the target letter white, allowing them to check later if participants had noticed the visual shift.
The behavioral data showed that the alerting tone made participants react faster, but it did not improve their ability to correctly match colors and shapes. People also responded faster when they were correct compared to when they experienced a visual illusion.
When looking at the physiological data, the researchers found a consistent pattern of the heart rate slowing down during the task. Most notably, the heartbeat decelerated more when participants experienced a visual illusion compared to when they correctly identified the target color.
“We were genuinely surprised,” Cobos Martín said. “Initially, we expected to replicate one of our previous findings, where the heart slowed down when a very faint stimulus reached conscious awareness. But the pattern here was different.”
The stimuli in both studies were not directly comparable, as the previous study involved a target that was sometimes completely missed. In the current study, the target was always consciously seen, but it was just not always perceived accurately.
“This led us to explore a different interpretation,” Cobos Martín explained. “The heartbeat slowing we observed may reflect an internal salience signal, the body marking that something unexpected or important has happened, such as making a perceptual error.”
This internal alert relates to the salience network, a brain system dedicated to detecting unexpected or important events. When a person makes a mistake, this network might send a signal to the body to briefly slow the heart down. This suggests the body tends to provide negative feedback about errors through changes in cardiac activity.
Additionally, the unexpected white letters revealed hidden differences among the participants. Those who did not consciously notice the white letters showed a stronger heart rate drop during their errors than those who did notice the change.
“For the general public, the message is straightforward: your body constantly influences how you perceive and interpret your surroundings, often without your awareness,” Cobos Martín explained. “Conscious experience is not created by the brain alone, but emerges from a continuous conversation between the brain and the body.”
As with all research, there are a few limitations to keep in mind. The scientists warn against assuming that the heart actually controls what we see.
“The effects we observed are very small and operate on a millisecond timescale, and they do not determine what someone sees,” Cobos Martín said. “Instead, they show that the body subtly participates in perceptual processes that we usually attribute only to the brain.”
“Another key caveat is that these results reflect correlations between cardiac dynamics and perceptual outcomes. To understand the underlying mechanisms — and to know whether the heart’s activity plays a causal role — we need more research, ideally with methods that can directly manipulate heart–brain interactions. So the message is not that the heart controls perception, but that perception emerges from a dialogue between the brain and the body.”
Expanding this line of work could help researchers map out how the nervous system and the internal organs work together to create human awareness.
“My next goal is to move beyond correlational findings and test whether heart–brain communication plays a causal role in conscious perception,” Cobos Martín told PsyPost. “It’s a difficult question, but central if we want to understand consciousness as an embodied process too.”
“I’ve already applied to several funding schemes to pursue this direction. My Marie Skłodowska-Curie proposal, for instance, received a very high score (93.6) but couldn’t be funded for budget reasons. Still, that evaluation — together with new, unpublished data suggesting that messages from the heart to the brain differ as a function of perception accuracy — encourages me to continue.”
“Demonstrating a causal contribution of heart–brain dynamics will take time, but every step matters,” Cobos Martín continued. “And I believe this work could also inform ethical discussions about artificial intelligence systems that lack this physiological grounding.”
“To close, I think the main message of our study is that human behavior and conscious perception cannot be understood by studying the brain in isolation. The brain is always interacting with the body—receiving signals from the heart, the gut, respiration, and many other physiological rhythms. Our findings suggest that the organism as a whole plays a role in how we process the world around us, even in very fast perceptual decisions.”
“Beyond that, I’d like to add a broader reflection,” Cobos Martín said. “Neuroscience and AI research are beginning to explore biological–computational hybrid systems, such as brain organoids connected to computers. These organoids can already perform simple tasks, even though we still don’t know how to train or optimize them effectively. Their existence pushes us to reconsider what we consider necessary for conscious processing.”
“At the same time, it is striking that we invest so much effort trying to imagine whether artificial systems might one day become conscious, while often overlooking that many living beings around us—animals with emotions, sensory worlds, and adaptive behavior—may already have forms of consciousness that differ from ours.”
“For me, all of this reinforces the importance of adopting an embodied perspective: consciousness emerges from the dynamic interaction between brain and body, and understanding that relationship will be key both for neuroscience and for the ethical development of future AI systems.”
The study, “The heart knows you are wrong: Heart rate modulations associated with perceptual errors,” was authored by María I. Cobos, Pedro M. Guerra, and Ana B. Chica.
