What to expect of a book with such a title? In this neuroscience-obsessed age, the best guess would be an enthusiastic account, illuminated with dramatic, if misleading, colour images of the brain regions that light up when people placed inside an MRI scanner are asked to think about their social relations. Or, by contrast, philosophical reflections on free will, the intentional stance and theories of mind. Refreshingly, however, Mindwise is free of such neuro- or philosophical ruminations; it takes for granted that we and our fellow humans have minds, and can exercise free will. Nicholas Epley, a professor of behavioural science at the Chicago Booth business school, by and large takes the internal workings of our brains for granted, and focuses instead on the common – and sometimes uncommon – sense of how we understand our own thoughts and actions, and, above all, read the thoughts and intentions of others.

Admittedly there is a cartoon of the human brain and the almost obligatory reference to the region supposedly engaged in social interactions and judgments, the medial prefrontal cortex (MPFC). But the book is largely built around rather classical observations and experiments in social psychology, enhanced, as is the way of things with popular science books, with personal anecdotes, of which perhaps the less said the better. After all, as Epley points out, humans, as social animals, have been making such judgments about others' intentions since their evolutionary dawn, without needing to bother about mirror neurons and the role of the MPFC.

You think you know what your workmates make of you? Wrong, Epley shows. Your guesses are not much above chance. Even worse, you think you know what your lover or partner makes of you? Well you are more likely to be right than about your workmates – but only slightly. You think you can predict the emotions and intentions of others? Well yes, but not half so well as you expect. Men think differently from women? Yes, but only marginally, and the overlap is so great as to make generalised gender-based judgments useless.

Such common and confident misbeliefs can have serious consequences. Following an earlier insight by Charles Darwin, the American psychologist Paul Ekman claimed, with much attendant publicity, that he could detect emotional feelings such as anger, fear or guilt, even among those trying to hide them, by observing transient facial "microexpressions". He sold his method to the government, and the US Transport Security Administration used it to screen passengers standing in airport security lines. As Epley drily reports, of the 2 billion passengers who travelled through US airports between 2004 and 2008, agents trained in the Eckman method detained some 152,000 people, resulting in 1,083 arrests – but no terrorists. The most common category was of "illegal aliens". An expensive way, Epley concludes, of racial profiling.

To mind-read at all, you have to believe that those with whom you interact have minds. At worst, people are defined as non-humans. The Greeks did it with their category of barbarians, slave owners with their slaves. The Nazis did it by classifying Jews and Roma as untermenschen. In 1879 a court case in Nebraska overthrew the US government's contention that Native Americans were not humans but mere objects that could be moved about at will. And – though Epley's consistently masculinist account manages not to reflect on this (I suspect he sees his readers largely as male business-studies students) – something similar has been true for men's views of women through much of history.

Then there is the tendency, above all of the rich towards the poor, of regarding others as mentally slow or stupid. Thus Michael Brown, the director of the US Federal Emergency Management Agency, castigating those who failed to evacuate New Orleans in advance of hurricane Katrina, asserted that the death toll was "going to be attributable to a lot of people who did not heed the advance warnings". As Epley angrily reflects, it did not occur to Brown that what those who stayed lacked was not mental capacity but rather money for a hotel or a car to leave in. Conservative MPs braying about the fecklessness of those who need food banks, or psychologists claiming that the British poor are short on mental capital but might be lifted out of poverty through a course in cognitive behaviour therapy, are the cisatlantic equivalents of Brown's argument.

But Epley is equally dismissive of those who believe that you can resolve conflicts by trying to see the other person's point of view, from George W Bush claiming on meeting Vladimir Putin that he found him "straightforward and trustworthy … I was able to get a sense of his soul," to Barack Obama urging Israelis and Palestinians to put themselves in the others' shoes. Fundamental conflicts of interest are not just misunderstandings. Straight talking, he concludes, is better than fancy mental guesswork.

The obverse of refusing to accept the mindfulness of others is to attribute minds to non-humans or inanimate objects. It's OK to speculate on whether chimpanzees have a theory of mind, or whether dogs can think, but it is only a step from this to a world inhabited by gods and demons who can be influenced by prayer – or to humanising technology. "Don't anthropomorphise your computers. They don't like it," said a notice pinned to a door in my old university department. And who hasn't pleaded with their car when it fails to start on a frosty morning? The robots in Star Wars might not be able to pass the Turing test, but it is hard not to empathise with them, and even more with the huge-eyed ET begging to phone home – Epley is good on the importance of eyes.

The book needs to be read with a modicum of scepticism though, especially when it comes to the unreferenced anecdotes. To call Gordon Brown "almost legally blind" is something of an overstatement; more seriously, the Swedish galleon the Vasa did not capsize on its maiden voyage in 1628 because, as he asserts, Swedish and Danish carpenters working on the left and right of the ship were using different measures, but because the grandiose poop deck made the ship top-heavy.

Towards the beginning of the book, Epley sets his readers a test. Think of a task you have to perform and your best- and worst-case guesses for the date and time by which you might complete it. On the basis of his experience he bets you'll be wrong, and won't even manage to finish it by the latest time you imagine. I played his game in writing this review and, for better or worse, met my self-imposed deadline. But then, as Mindwise warns us, the author's own generalisations are just that – averages mask huge individual variations.

• Steven Rose's latest book, Genes, Cells and Brains, written with Hilary Rose, will be out in paperback in March.