When were you last lied to? To your knowledge, obviously. Was the lie something that mattered? Was the liar convincing? Did they confess, or did you find them out? And how did you react? Maybe with anger. Maybe with hurt bemusement. Or contempt – like my grandmother, who had a stock retort for anyone who tried to pull the wool over her eyes: “I hate liars. They’re worse than thieves.”

Did you feel, afterwards, that you’d been easy to fool? If so, you’d be in good company. It’s the norm to assume communication is honest – and that’s something to be thankful for, because we’d live in a miserable, suspicious world otherwise. Less helpfully, it’s common to assume that body language gives away dishonesty when it does arise. Liars look shifty, in the popular imagination. They cough before they speak, fidget and don’t look you in the eye. Unfortunately, none of these cues are very reliable.

People who convince themselves of their own truthfulness while being dishonest may act no differently to normal. The weight of empirical research shows it’s hard to identify even very purposeful liars from their behaviour. A meta-analysis from 2006, “Accuracy of Deception Judgments”, by social psychologist Charles F Bond of Texas Christian University and others, looked at more than 200 studies to find that people’s accuracy when distinguishing truth from lies isn’t much better than chance. A more recent review, 2019’s “Reading Lies: Nonverbal Communication and Deception”, led by Aldert Vrij of the University of Portsmouth, hammered home the point. People are mediocre judges of deception. This seems to be true generally, but the question of who we might find believable, and why, gets more complicated within certain relationship dynamics.

I once knew a woman, Julia, who by any measure was attractive and charming. She seemed a kind, sympathetic listener. She was generous with cake, hugs and praise. I loved her for all these things, yet I often felt guarded in her company for reasons I could neither put words to nor think about clearly. Her compliments were so warm one could feel dizzied. Within such a context, if she made improbable claims people tended to take them at face value. I know I did.

Her believability was filtered through a troubling pattern of behaviour. Sometimes she’d persuade me I had said things I didn’t remember saying. Other times she’d persuade me I’d imagined things she’d said. She would advise me on a practical problem – emphatically, in detail and with certainty, because she had a love of organisation – and I’d follow her guidance. Months later, she would express dismay at my choices and ask what had driven them. Over time my trust in my judgment eroded. If I was so very forgetful, I couldn’t rely on my own perceptions; I could barely feel them through a mental fog. She had the same effect on other people.

Within this fog, Julia said extreme things about people I knew – Cathy was mistreating a pet, Daniel was ripping off his mother, Pamela kept taking Julia’s belongings for use in a stalkerish shrine. I privileged Julia’s perception over my own, until I had distorted views of Cathy, Daniel and Pamela.

One day, the leopard ate my face. I learned Julia had been discussing my health with people. Under the pretext of concern, she’d claimed I had a range of illnesses, physical and mental, that I’ve never suffered from or matched criteria for. They included stigmatised conditions that people usually have strong reactions to. What she said was untrue. I asked a few of Julia’s other contacts if we could compare notes. We discovered Julia had set us against each other with a complicated web of falsehoods. Several relationships had broken down, extracting a painful toll from those involved.

The moment Julia realised we were on to her, she severed ties. She never explained her behaviour, nor could I tell whether she believed her own contradictory and false accounts in the moment of giving them. I have guesses, but I’m more interested in how the rest of us responded to her growing implausibility. As a rule, she was believed.

Anyone online these days is likely to have encountered the idea of gaslighting, or denying a shared reality, to manipulate someone into questioning their senses. The most effective gaslighters I’ve met also seemed more likely to be believed when they told common-or-garden lies, with one strategy supporting the other. After all, a gaslighter can isolate victims more effectively if their more basic lies are readily accepted by outsiders. Who the liar is – rather than what they’re saying – factors into their success, because humans are unfortunately prone to cognitive bias. Perceived credibility can be gendered and racialised. It’s also influenced by what psychologists call halo errors; we expect people to be truthful when we like them. Good looks, hospitality and generosity with compliments (at least to one’s face) are qualities that can buy undeserved leeway, without consciously being weighed in the balance.

Normal desire for connection can also muddy the waters. Take a situation such as friends sharing gossip. For the purposes of psychological research, gossip is often defined as unsubstantiated personal chat rather than as malicious activity per se. According to a recent review of evidence, “When and Why Does Gossip Increase Prosocial Behavior?”, led by Annika S Nieper of Vrije Universiteit Amsterdam, gossip can benefit your wider social group – provided the content is true. Anthropologists such as Robin Dunbar and Max Gluckman before him, have argued that gossip plays a part in forging social bonds. Sharing an inside scoop flatters the receiver because it implies trust, belonging or even, in whisper networks, the urge to protect. Such an exchange involves powerful feelings that serve a purpose when the whispers are accurate; but can be readily exploited by a liar. The flipside of heightened intimacy is lowered guards. Drama and mess can feel pleasurable, in a queasy way; it’s tempting to roll with a compelling story from a friend.

While I was writing my latest novel – a supernatural horror set in a 1920s hotel – I kept coming back to why we believe some people even as they make extraordinary, unsupportable claims. (Gothic fiction in general is littered with unreliable narrators, doubles and people not being quite what they seem.) The characters in my novel include a young woman who fakes clairvoyant visions to express socially unacceptable feelings, and a psychoanalyst who is skilled at “paltering”, or the use of factual statements to mislead. The ease with which the clairvoyant cons her audience inspires a little jealousy in the psychoanalyst, who bitterly comments that the audience must want to be deceived. In context, the line is meant to be an example of bad-faith victim-blaming. It’s also a stance that victims of deception can internalise; they may feel gullible to a fault once the lie comes to light, or even fear they had a vested interest in the ruse.

But rather than wanting to be deceived, there is a sadder explanation for extending the benefit of the doubt, at least in situations where warning signs can’t penetrate the fog. Freud wrote of disavowal: minimising a reality that we can’t tolerate. Some truths are painful and we protect ourselves from them by proceeding in a conflicted state of knowing and not-knowing. Julia was deeply familiar to me. I loved her, and valued the nurturing persona she cultivated. So, along with everyone else, I smiled at her exaggerations, while I pushed to the back of my mind her more disturbing capacity for damage. This is why, when I learned how she had misrepresented me, I felt something wordless I’d always known about her was finally in full view.

Being lied to can impair trust in several ways that outlast the original harm. First, and most obvious, is an ongoing suspicion that other people don’t mean what they say. This is both understandable and a distortion. Several studies show that telling one or two white lies a day is common, but the percentage of people who lie prolifically is estimated in single figures. Second, and more subtly, there is the disturbing knowledge that people in general, good people, struggle at lie detection. In a conflict, they cannot be relied upon to back an honest person over a liar. Third, you may lose confidence in your own judgment, and it has to be re-earned. The best course of action, it seems to me, is to attend to any sense of being divided against oneself. Confusing, wordless unease at the back of one’s mind should be pulled into the light as a matter of course.

A tricky balance must be struck between the kind of dignity my grandmother once showed – when telling a liar to sling his hook – and faith in humanity, because the desire not to be fooled again can go badly astray. There’s a comforting simplicity to viewing everyone sceptically: a liar won’t get through and no one else will, either. What helps me is knowing how very much better my life has been without Julia in it. Outside her influence, optimism is easier, which includes realising most people are honest – and deserve to be met as such.

Some names have been changed. Hokey Pokey by Kate Mascarenhas is out now (Head of Zeus, £16.99). Buy it from guardianbookshop.com for £14.95