At a literary festival not so long ago, I interviewed the novelist Sophie Hannah – known particularly for her twisty psychological thrillers – and the subject of grudges came up. Hannah’s forthcoming book is a non-fiction study of the power of the grudge to transform our lives, if we work out how to deal with them sensibly and effectively. To be clear, I don’t believe she is advocating tracking down the schoolmate who stole your best marble when you were seven and exacting revenge; more along the lines of working out what your grievance is telling you about yourself and how best to deal with it. I nearly forgot to ask another question because I found myself marooned in the memory of a decades-old dispute over a parking space.

To this end, she had given each audience member a slip of paper, on which they could fill out their most deeply held grudge and return it to her. Bookish event-goers can be a little wary of audience participation, but her request prompted a flurry of activity: ruminative looks, darkened brows and feverish scribbling.

All of which frenzied fulmination is fascinating in the light of the findings of psychologists at Yale, the University of Oxford and University College London, who reported that we’re actually rather better at thinking good of people than writing them off as rotten apples. Molly Crockett, one of the authors of the paper, explains that our brains form “social impressions in a way that can enable forgiveness”, and that this is useful because “people sometimes behave badly by accident” and that “we need to be able to update bad impressions that turn out to be mistaken. Otherwise, we might end relationships prematurely and miss out on the many benefits of social connection.”

It’s quite true that the greatest friend is the one who will provide unasked-for reassurance the morning after the night before, as the novelist Beryl Bainbridge once described of her pal Bernice Rubens: “I got drunk at one of her dinner parties and she rang me the next day because she knew I’d be feeling remorse, to tell me I behaved beautifully, which wasn’t true.” The helpful ones who make contact to give you advice about drinking apple cider vinegar and respond to queries about indiscretions with a hesitant “We-ell” are asking to be given the bum’s rush, in my opinion.

How often have you raged about the ignominies visited on you, only to realise you might do better to look in the mirror?

However, these are trifles compared with the more serious stuff of life; as the scientists suggest, it’s one thing to weigh up the positive and negative aspects of a person’s behaviour, but quite another to bend so heavily towards forgiveness and second chances that another’s harmful actions are tolerated, and even normalised, to the detriment of those around them. The report acknowledges, for example, the danger that forgiving can present in the context of bad relationships; and, while we know that women in abusive domestic situations frequently stay in them because of an entirely justified fear of violent reprisal should they leave, the emotional consequences of hoping for behavioural improvement that will likely never come can also be highly destructive.

Forgiveness is both complex and personal: if we set the bar for casting miscreants into the outer darkness too low, we risk the isolation of perfectionism; if we set it too high, we might well find ourselves seething with suppressed resentment. And there is also the issue of projection. None of us is without flaws, nor past incidents in which we know we have behaved less than well; if we seek forgiveness for our own frailties, why should we not bestow it? How many times have you raged about the ignominies visited upon you, only to realise you might perhaps be better off looking in the mirror? As the late Josephine Hart, author of the novel Damage, once said to me: “It’s like Medea out there.”

On a macro level, traumatised communities that have been through processes of truth and reconciliation generally find it easier to face the future than those that haven’t. But such processes also rely on a basic willingness to admit wrongdoing and culpability; as we watch the horrendous unravellings prompted by the #MeToo and other social justice movements, it’s evident that the impunity that abusers have shown and continue to cling to inflicts serious consequential damage.

But we can derive something of great potential value from the idea that we are, as human beings, capable of setting the past aside. The propensity of social media to encourage a discourse of denunciation, in which a person’s transgressions co-exist with their present lives, in which the line between “calling out” and futile, zero-sum bullying is ever blurrier, is not, ultimately, a pathway to happiness. There is much to be angry about, and there are many perpetrators of cruelty and malfeasance to confront. But in the week of Yom Kippur, the Day of Atonement, it’s reassuring to see a study confirming the reparative power of admitting our imperfections, saying sorry and moving forward.

• Alex Clark writes for the Guardian and the Observer