Recently, I was scrolling TikTok when my brain failed me. I watched a video of Donald Trump berating CNN journalist Kaitlan Collins for “not smiling”, after she questioned him on matters concerning sex offender Jeffrey Epstein.

And I scrolled past.

I didn’t pause. I didn’t get angry. I didn’t consider the implications of a person – let alone a president – saying such insulting words to another human being. Yet I’m not a monster. Writing this column, I’ve reflected on those remarks, and found them abhorrent, unprofessional and sexist.

My brain didn’t fail because I don’t care. It failed because of an evolutionarily useful neurological trait called habituation. Realising this made me want to find out exactly how it affects our lives and how to overcome it – and when we should.

Habituation is the brain’s way of normalising our experience of the world so that we can get on with life. It’s an elegant neural shortcut. Without it, we couldn’t filter irrelevant stimuli and would instead be paralysed by sensory overload.

Right now, there’s trance music in the café I’m working from, my ski jacket feels cumbersome on my shoulders and a bright light is glaring nearby. Until I consciously thought about them, though, my brain had quietly tuned them out, habituating so that I could focus on these words.

Remarkably, this ability begins before birth. In the final trimester, fetal brain activity suggests babies can already habituate to repeated flashes of light and sound, learning to shelve familiar stimuli in order to attend to something new.

Habituation frees up neural resources so we can quickly focus on new stimuli that might kill us, feed us or otherwise aid our well-being. “We see this ability in every single species on Earth because it is important for survival,” says Tali Sharot at University College London.

Our ability to habituate can also help us cope with grief or chronic pain, normalising distress to make life more bearable. One striking example of this comes from research on people with locked-in syndrome, who are fully conscious but cannot speak or move except to blink or move their eyes. Asked about their happiness, the majority reported being content – vitally, the longer they had been locked in, the more likely they were to report that they had a decent quality of life.

Habituation can also motivate progress. For example, when the excitement of a new job fades, satisfaction plateaus due to habituation. Sharot says this diminishing spark of enthusiasm fuels our desire to advance. “Our response to good things dies down over time so that we are motivated to explore and progress.”

But habituation isn’t always helpful. If we ignore chronic pain, for instance, we risk delaying seeing a doctor. If we normalise toxic behaviour at work or home, we may tolerate what should never be accepted.

An inability to habituate is also a problem. “Almost all mental health conditions are characterised by some kind of impairment in habituation,” says Sharot. Studies suggest, for example, that people with depression disengage from negative events slower than those without depression. In other words, they find it difficult to habituate to bad news, delaying their emotional recovery.

Sharot’s recent and as-yet-unpublished work hints at another problem: people who make repeated risky financial decisions dull their emotional response to danger, increasing risk-taking over time. They have become habituated to a climate of risk. “You can see how that may be relevant to stockbrokers,” says Sharot.

On a trivial level, habituation also explains why our homes feel smaller than they once did, or why new clothes quickly seem uninteresting, leading to overconsumption.

Step back and slow down

So, how do we dishabituate? How do we teach our brain to notice again?

One route is mindfulness, in which you purposefully increase your awareness of the present moment. This has been shown in studies to reduce your likelihood of habituating to things like food – consider how you can easily overeat without thinking because you’re no longer actually noticing what you’re tasting.

Another is simply taking breaks – which might sometimes feel counter-intuitive. Leif Nelson at the University of California, Berkeley, and Tom Meyvis at New York University have shown that interrupting pleasant experiences – music, holidays, etc. – actually makes them more enjoyable, because breaks disrupt habituation. Likewise, they found that despite our natural inclination to take breaks from unpleasant experiences, doing so makes them more irritating because it prevents habituation.

Novelty helps too. If you run the same route over and over, you’ll enjoy it a bit less each time. “Just doing a different route occasionally means you will enjoy it more,” says Sharot. Same goes for moving furniture around in your house, sitting in a different seat in class or storing clothes away for a short time. “All these small things… you’d be amazed by how much joy you can gain from presenting new information to your brain. It can make a huge positive difference,” says Sharot.

Where dishabituation may matter most right now, however, is social media. “Over the last decade, we as a society have habituated to very rude behaviour online. We start habituating to bad things happening globally, politically or socially very quickly,” says Sharot. Constant exposure makes the shocking feel normal, meaning we no longer respond to it appropriately. Especially concerning is children’s increasing exposure to the internet’s hostility. A number of studies have shown that exposure to media violence desensitises children’s emotional reactivity to future violence, both in media and in real life, and has been linked with an increased risk of violent behaviour in later adolescence.

The solution, says Sharot, is as simple as stepping away. “We need to see the world through fresh eyes again,” she says. “Small changes can make a huge impact.”

I’ve taken this advice to heart by removing social apps from my phone for a while, booking a few shorter breaks rather than one long holiday and even switching gyms to expose myself to new surroundings. The hope is that I’ll experience not only more joy, but a sharper emotional response when I return to social media, so my brain can once again notice the things that truly deserve my attention.