Every modern generation has had its own idiosyncratic obsession with telepathy, the hope that one human being might be able to read another person’s thoughts. In the late 19th century, when spiritualism was in vogue, mind-reading was a parlour game for the fashionable, and the philosopher William James considered telepathy and other psychic phenomena legitimate subjects of study for the new science of psychology. By the 1960s, the Pentagon was concerned about Soviet telepathy research and reports that they had established remote communications with submarine commanders. In the 1970s, one ambitious Apollo 14 astronaut took it upon himself to try broadcasting his brainwaves from the moon.

In our technologically obsessed era, the search for evidence of psychic communication has been replaced by a push to invent computerised telepathy machines. Just last year, an international team of neurobiologists in Spain, France and at Harvard ­set up systems that linked one brain to another and permitted two people to communicate using only their thoughts. The network was basically one massive kludge, including an electroencephalography cap to detect the sender’s neural activity, computer algorithms to transform neural signals into data that could be sent through the internet and, at the receiving end, a transcranial magnetic stimulation device to convert that data into magnetic pulses that cross another person’s skull and activate certain clusters of neurons with an electrical field. With this contraption, the researchers were able to send a signal of 140 bits (the word ‘ciao’) from one person’s brain to another.

This apparatus is complex, expensive and extremely low-bandwidth, achieving a speed of about two bits per minute. Nonetheless, this study and others like it inspire a wave of hope that it might one day be possible to read another person’s thoughts. It’s easy to see why people won’t give up on the idea. Telepathy promises an intimate connection to other human beings. If isolation, cruelty, malice, violence and wars are fuelled by misunderstandings and communication failures, as many people believe, telepathy would seem to offer the cure.

But findings from affective neuroscience, social psychology and the new neuroscientific study of empathy suggest that tapping directly into other people’s thoughts would be a pretty bad idea. In the past decade or so, this research has revealed that we already have deep insights into what other people feel and think. We really do have a sixth sense, but it’s psychological rather than psychic, made up of an entirely natural and completely human blend of emotional intuition and clever reasoning.

The more we know about empathy and ordinary human mind-reading, the less it looks like a way to achieve world peace. Technologically assisted telepathy could exaggerate flaws in our moral thinking and saddle us with unbearable intimacy, encouraging us to tune out the suffering of the most vulnerable. Emotional-mindreading is no guarantee of kindness; it is also how psychopaths and bullies manipulate and torment their victims. This research suggests an entirely sensible, completely ordinary, not-at-all-clairvoyant prediction about the future: rather than a dreamy bliss of togetherness, artificial telepathy would be a nightmare.

This new appreciation of the limitations of empathy is in part the result of a surprising discovery about brain organisation. One of the general rules of neurobiology is that many mental tasks are handled by dedicated anatomical regions of the brain. The motor cortex, for example, controls body movements. The visual cortex is specialised for processing information from your eyes. Other parts are for remembering, for analysing objects, for feeling emotions, or for functions as specific as verbal fluidity or measuring rewards. So if you watch a ball roll down a hill, for example, parts of your brain involved in recognising objects, analysing movements, and ensuring that your eyes move in sync with an object all become active.

This rule of thumb still holds, but a big asterisk was put next to it in the 1990s, when a group of Italian scientists discovered that primate brains analyse the actions of other similar creatures in a special way. Their discovery was initially made with monkeys, but something similar happens in humans too: as you watch another person do something, your brain responds with a rough mental simulation of the action. When you see the Brazilian footballer Reynaldo kick a ball, for example, the parts of your motor cortex that would be involved in preparing your legs and feet to move and in co‑ordinating that movement also become active. When he runs or falls or leaps in joy, so do you – but only in your mind. Other people’s bodies seem to be inside your head, and that is the way you comprehend their motion. ‘We use ourselves as a heuristic, an approximation of the other,’ says the social neuroscientist Christian Keysers of the Netherlands Institute for Neuroscience and the University of Amsterdam, who worked with the Italian team in the late 1990s.

This is how laughter or weeping spreads through a room, or crowds suddenly turn violent or panicky

Keysers and others have since found that the same exception applies to sensations and emotions: you respond to other people’s experiences by recreating them in your own mind. You have a ‘vicarious brain’, he says, ‘a brain that uses a lot of its own private space to represent automatically the actions, sensations and motions of others’. If you see an angry face, even just momentarily, the neurons that cause you to narrow your eyes and fix your jaw flicker with activity. In one series of neural imaging experiments, Keysers had people taste a disgusting liquid (quinine), listen to an appalling story about finding a maggot-infested dead rat in bed, or look at pictures of actors reacting with disgust. All three situations – seeing, imagining and experiencing – activated some of the same brain regions, albeit in slightly different ways. More recent findings suggest that our brains also simulate other people’s good feelings; seeing someone look pleased by a sugary drink or a happy event causes your own mind to respond in a similar way.

The vicarious experience of emotion might even affect your own mood. A baby often cries when it hears another baby crying, but for adults, this phenomenon of emotional contagion is more subtle. People who heard someone speaking in a sad tone of voice, for example, subsequently rated their moods a bit lower than those who heard neutral or cheerful voices. This is also how laughter or weeping spreads through a room, or crowds suddenly turn violent or panicky.

It’s not clear why our minds work this way, but Keysers and others point out that it is a good way to get fast insights with very little information: just one glance tells you what you need to know. For a social species like ours, anticipating what someone else is about to do can be a major advantage.

This intuitive, automatic fellow-feeling is not the only kind of mind-reading humans do; we also learn more deliberate, strategic methods to infer other people’s thoughts. In the first years of life, children become theorists of desire: they notice that other people’s mental states predict their actions, and they begin figuring out what other people want as a way to anticipate what they will do. By adulthood, we have learned to infer other people’s motives and thought processes, read hidden or mixed emotions, detect when people are faking their feelings, even pick up on irony. The cognitive neuroscientist Uta Frith considers this ‘theory of mind’ to be a hallmark of human cognition.

Together, the intuitive and the strategic components of fellow-feeling enable empathy, the ability to step into someone else’s mind and know what they feel. Being connected to other people in this way is a deep part of our nature; we might be selfish and competitive, but we are also hitched to one another, obliged to take on other people’s pleasures and their suffering. It seems to explain the strange human phenomenon of moral behaviour – the peculiar tendency of people to help one another even when it is risky and difficult. If your joy is my joy, and your pain my pain, this sort of altruism only makes sense.

But in case you hadn’t noticed, the sophisticated, multi-layered capacity for fellow-feeling doesn’t prevent people from behaving terribly towards one another. They fight, murder, abuse and steal. Even those who don’t purposely harm others often ignore other people’s pain and fail to help those who need it.

Maybe our natural ability to empathise just isn’t strong enough. Perhaps machine-assisted telepathy could help, amplifying the faint signal of compassion into an intense blast. For the moment, let’s just assume that the monumental technological and biological challenges could be resolved, and we could invent a device that would effectively transmit one person’s experience to another. What would happen if we turned up the volume on empathy?

To begin with, we might help psychopaths – people who ruthlessly exploit others – be even better at what they do. Research from Keysers and others reveals that these apparently cold-blooded predators are actually good at detecting emotions. In one 2013 study, Keysers asked 20 criminal psychopaths to watch short videos of two people either caressing or striking one another’s hands – a simple way to evoke an emotional response that in ordinary people activates brain regions associated with emotional processing. Initially, these participants did not have much activation in regions involved in feelings or pain. But when Keysers instructed them to empathise while watching, their patterns of neural activity became fairly normal.

a mind-reading machine wouldn’t necessarily turn a psychopath into a creampuff

His interpretation is that these violent predators can feel empathy, but often choose not to. They deploy the ability strategically in order to win over their victims and secure their trust, and then shut it down in order to swindle, rape and kill. So a mind-reading machine wouldn’t necessarily turn a psychopath into a creampuff. Instead, he might become an even more effective manipulator – more cunning, more perceptive, and harder to outwit.

The rest of us aren’t really so different: we also evade or down-regulate our mind-reading abilities when it becomes painful or inconvenient. In one 1988 experiment, psychologists in Canada set up a donation table in a busy corridor and monitored the pathways of passersby. If the table featured a picture of a dejected child, people veered far away from it, in order to avoid getting their heartstrings jerked. In another experiment, people told that a fellow participant had been given electric shocks downgraded their opinion of him – and justified it by concluding that he probably deserved it. Rather than feel his feelings, they found ways to emotionally distance themselves through rationalisations. In similar ways, people frequently underestimate the suffering of foreigners, people of other ethnicities, or prisoners.

These and other findings in the new science of empathy converge upon a new appreciation of how malleable empathy can be. It can be used for good or ill; it can be turned up or down. It is motivated, argues Jamil Zaki, the director of the Stanford Social Neuroscience Laboratory. ‘We tend to view it as something relatively automatic, but people exert control over their experiences of empathy,’ he says. Although it seems self-evident that people who feel more empathy will behave more morally, in practice there is only weak evidence that feeling someone else’s pain induces you to do something about it. Some data even indicates that people who sense others’ emotions most intensely tend to avoid situations that will expose them to deep suffering. Their own pain prevents them from helping those who need it the most.

Amplifying empathy is not even a sure-fire means of building trust or dissolving suspicion; other findings from empathy research suggest that encouraging people to consider the perspectives and thoughts of those they already distrust and dislike can backfire. ‘As a premise, it’s a terrible idea,’ says Zaki. ‘I don’t think that understanding what people are feeling would make you like them.’

He points to studies that instruct rivals to empathise with one another, and have the paradoxical effect of fostering unethical behaviour. In competitive negotiating scenarios devised by the psychologist Adam Galinsky of the Columbia Business School, for example, people who were told to think about the mindset of a rival became more likely to lie or cheat in order to win. Galinsky suspects this is because that act of mind-reading serves as a reminder that a rival is capable of being equally dishonest.

In other experiments, people asked to consider the feelings and perspectives of rival groups were more selfish, more intolerant, and judged outsiders more harshly. In a study pairing Mexican immigrants and white Americans, the neuroscientist Emile Bruneau of the Massachusetts Institute of Technology found that asking lower-status immigrants to take on the perspective of the dominant group tended to lower their opinions of the higher-status whites.

The more we know about empathy, the less it seems to guarantee moral rectitude. People generally feel more empathy toward members of their own racial, political or social ‘tribe’, and limit the amount they extend to outsider. It directs you to respond to the needs of the person right in front of you and downgrade those who are abstract and far away. Empathy often biases you toward people who look and act like you, at the expense of those who do not. It is easy to manipulate, responding strongly to cuteness, proximity, or particularly heartbreaking details. ‘A morality based on empathy would lead to preferential treatment and grotesque crimes of omission,’ writes Jesse Prinz, a philosopher at the Graduate Center of the City University of New York.

Once we understand the motivational nature of empathy, we could figure out how to compensate for its biases

A telepathy machine, if it could ever be built, would undoubtedly have wonderful applications. It could allow people who are immobilised by a stroke or neurological disease to communicate, or create incredible opportunities for artists to collaborate. But it seems unlikely that it could broadcast world peace. Empathy is too compromised, too complicated, and too subject to intentions and motivations to be a magic solution for our moral problems. It is far too human.

Zaki considers it extremely unlikely that a mind-reading machine could ever be built. (‘It’s a lot further on the horizon that people realise,’ he says). He has a different invention in mind – a cognitive innovation rather than a technological one. As we come to understand the motivational nature of empathy, we should be able to figure out how to compensate for its limitations and biases. Zaki does not see empathy as a salve for all our moral problems, but he also believes that it is possible to make use of what it can do, which is provide a strong emotional motivation to act on behalf of others.

If we know that empathy favours the specific and familiar over the foreign and abstract, we can seek out, as our inspiration, personal details about someone far away who needs help. If empathy is easily overwhelmed and blocked by intense suffering, we could compensate by regulating how much information about tragedy we consume. In this way, we could hijack it, redirecting it away from in-group bias and toward morally courageous acts. We would strategically harness the power of what nature gave us – the remarkable ability to see into someone else’s mind and to feel what they are feeling – for the service of moral good.

Just as psychopaths turn down their empathy in order to prey upon people, we might learn to up-regulate empathy in exactly the right situations – to inspire us when abstract moral intentions aren’t enough. We can deliberately put ourselves in empathy’s way.

That might sound like a relatively modest goal, compared with past efforts that sought to read ghostly messages from the spiritual realm, or win the Cold War via psychic warfare, or use the internet to let neurons talk directly to one another. But this vision of telepathy – as a way to help people actually live up to the moral standards they believe in – could turn out to be exactly the one we need.