Browsing Spotify for music to pull me through the slog of a grey February in New York, I came across the work of Labi Siffre, a 1970s artist I had never heard of. I was immediately taken with his delicate voice and simple, intimate musical arrangements.

Shortly after my precious discovery, Labi Siffre turned up in random places. I heard his crooning in coffee shops, a friend put him on at karaoke, and the singer-songwriter Lucy Dacus mentioned him as an artist who epitomised yearning. Labi Siffre was following me. Or at least that’s how I’d think about it if I didn’t know better. Instead, I thought: Baader-Meinhof.

The Baader-Meinhof phenomenon, also known as the frequency illusion, is a type of cognitive bias where, once you learn about something – such as a word, person or concept – you start to notice it more frequently. Your best friend clues you in on a slang term, and suddenly you see it endlessly in your feed. Your brother recommends a supplement, and you start repeatedly hearing ads for it. It feels eerie, especially if you don’t have a name for what’s happening.

Terry Mullen recalled feeling similarly when, after learning about a 1970s terrorist group called the Baader-Meinhof Gang, he encountered another mention of them the next day. He wrote to a newspaper about it in 1994. About a decade later, a Stanford professor proposed that a mix of selective attention and confirmation bias explains why something you are newly aware of might seem to happen all the time.

I first learned about this phenomenon in a psychology class at university. Today, when I feel it in action, I mutter ‘Baader-Meinhof’ under my breath. It helps me notice what I’m noticing, and the knowledge that my brain is primed for recognition dispels the feeling that I’m being sent some coded, mystical message – musical or otherwise.

As you read, do you scribble around the edges? Over the years, writers have sworn by the practice. Edgar Allan Poe once wrote: ‘In getting my books, I have been always solicitous of an ample margin … for the facility it affords me of pencilling suggested thoughts, agreements and differences of opinion …’

I tend to make notes digitally nowadays. And if I include magazines and newspapers, most of my reading is online, where I probably could annotate with the right software, but can hardly doodle. That’s a shame. Apart from the fact that annotating boosts recall, we’d lose something if freeform margin-writing faded away. One of the meanings of ‘marginalia’ is ‘non-essential’, yet it’s anything but.

For one thing, scribbled-upon books have helped reveal the web of influences between writers and thinkers. Herman Melville’s annotated copy of John Milton’s Paradise Lost shows how it fed into Moby-Dick. And Charles Darwin’s comments in his books – from Charles Lyell’s Principles of Geology to his grandfather Erasmus Darwin’s The Temple of Nature – inform how they shaped his theory.

Marginalia can reveal everyday insights too. Historians occasionally find scrawls in manuscripts that speak of long-dead readers’ lives. A recent exhibition in Dublin features scriptures doodled on by medieval Irish monks. One described feeling ‘ale-killed’ (hungover); another complained about his materials (‘New parchment, bad ink. O I say nothing more’). Turns out nuns did similar. In 2022, researchers found surprisingly modern cartoons of people around the edges of an 8th-century Act of Apostles. A nun etched them, perhaps mischievously.

Reading about these examples made me think I should annotate more – not everything, but the writing I care about. Or perhaps I’ll take a leaf from a wholesome TikTok trend I discovered while writing this: gifting an annotated book. This 21st-century practice suggests digitalisation may not be annotation’s death knell after all. Poe might have approved.

When I’m going through something stressful, I have a strong urge to think out loud about it with someone I trust. There are probably several reasons I end up feeling better: my listener helps me avoid catastrophic thinking, or reminds me that they have my back if things get worse. But another likely reason is that having the chance to describe a difficult situation in detail – even if you’re just describing it to yourself, as in a journal – invites you to see the full picture, and in many cases, it’s not all bad.

Research by Christian Waugh and colleagues at Wake Forest University in North Carolina underscores this and highlights its potential for helping us manage our emotions. They focused largely on people’s experiences during the COVID-19 pandemic, based on data they collected then. When people reflected on a stressful experience they’d been having, and were prompted to describe six specific elements of the situation, they tended to list at least one that was positive (such as spending more time with family during the pandemic). Having more positive elements in the list was associated with feeling less negative and more positive emotion following the task. Taking some time to elaborate on one of the positive aspects seemed to help people feel better, too.

It can be annoying to be told to ‘look on the bright side’ or ‘find the silver lining’. But personal trials often come with opportunities for growth or self-insight; grief or separation sometimes lead to new connections; and even mundane sources of frustration (a traffic jam, say) can contain small points of pleasure or relief (enjoying a song on the radio that you would’ve missed). Where there are such leavening factors, taking a moment to talk or write about the experience could help us make the most of them.