In 2005, a paper in one of psychology's leading journals announced a number: 2.9013. Have at least 2.9013 positive emotions for every negative one, it said, and you flourish. Fall below it and you languish. The figure came from equations borrowed from fluid dynamics, the maths of turbulent water, and it spread fast. The paper was cited hundreds of times, and a popular book sold it as the ratio that would change your life. Just as zero degrees Celsius is special for water, the book suggested, the ratio "may well be a magic number in human psychology".
A Finnish group questioned the maths in 2008, and few noticed. Then Nick Brown, a graduate student who found the maths suspicious, teamed up with Alan Sokal and Harris Friedman to check it. Their verdict was that the claim was "entirely unfounded". The equations did not apply, and the way they had been applied was riddled with errors. The journal formally retracted the modelling. Fredrickson, one of the authors, conceded that the maths was "questionable" and that she lacked the expertise to defend it, while holding that the evidence for a ratio was solid.
That is the first lesson about positive thinking, and about the way you think in general. It deserves careful thinking too. A number with four decimal places is not automatically true. It is just harder to argue with.
Your thoughts do shape your brain, your mood and even your health. But not in the way the posters say. Ahead: where "neurons that fire together, wire together" really comes from, what savouring adds to a good moment, the Roman emperor's line about obstacles, the earthquake that showed what dwelling does, the eight minutes that show it again, what eight weeks of mindfulness did to the brain, how much longer the most optimistic people lived, and the point at which positivity turns toxic.
What "rewiring" really means
The famous line is "neurons that fire together, wire together". It is usually credited to whoever is selling the book. It is a summary of an idea from 1949, by the Canadian Donald Hebb: when one brain cell repeatedly helps to fire another, the connection between them strengthens. Hebb was precise about it. The first cell has to take part in firing the second, firing just before it, not merely at the same time.
So a single positive thought does not rewire anything. Repetition does. One kind thought is a visit. A habit of them is a road. How to Rewire Your Brain and Change Limiting Beliefs has the London taxi drivers who memorise around 25,000 streets and grow a larger rear hippocampus the longer they drive, and the adults who learned to juggle and gained grey matter, then lost some of it when they stopped.
The brain changes around what you practise, and thinking is a kind of practice. You are not stuck in any emotional state. You are, however, shaped by the ones you rehearse most.
Savour the good
The usual advice here is sound: when someone pays you a compliment or something goes right, do not wave it away. Stay with it.
There is a word for this, savouring, and it has been measured. For 30 days, 101 people reported the good things that happened to them, how they responded, and how happy they felt. Savouring did two things. It carried part of the effect of a good event through to their mood, and it made that effect bigger. The good thing was the same. Lingering on it was what turned it into happiness. A compliment you brush off is a gift left on the doorstep.
So when something good happens, notice it on purpose. Say it out loud, tell someone, or simply stop and take it in before rushing to the next thing.
Reframe, and keep it honest
Reframing does not mean pretending a setback is good news. It means asking a better question about it.
Marcus Aurelius, the Roman emperor, wrote it down nearly two thousand years ago, in the private notebook we now call the Meditations: "The impediment to action advances action. What stands in the way becomes the way." He wrote it for himself, not for a poster. puts the whole notebook into plain modern English.
Two questions are a good start. When criticism stings, ask what in it is useful. When a plan fails, ask what you know now that you did not before. How Changing Your Thoughts Changes Your Day, linked below, has how reappraisal works and how to catch the thought first. 5 Practical Ways to Cultivate a Positive Mindset, also linked below, has the exercise that pictures the goal and then the obstacle, which works better than picturing the goal alone.
It also helps to step outside your own head. 5 Ways to Build Your Inner Strength and Live a Fulfilling Life has the people preparing a speech who thought through their nerves in their own name, "Why is Sam nervous?", and felt less anxious and spoke better than those who used "I".
How you explain a setback matters as much. 5 Practical Ways to Cultivate a Positive Mindset has the Harvard men who, at 25, explained bad events as permanent, pervasive and personal, and had poorer health between 45 and 60. So put the thought through three questions. Will this last forever? Does it touch everything? Is it all down to me? The honest answer is rarely yes to all three.
Dwelling is not thinking
There is a habit that looks like thinking and works against you: going over and over a bad feeling, asking why it happened and what it means, without moving towards anything.
It was caught in an unusual natural experiment. In 1989, 137 students in California had filled in questionnaires about their mood, and about how they tended to respond to feeling low, just 14 days before the Loma Prieta earthquake struck the San Francisco Bay Area. They were followed up 10 days and 7 weeks after it. The students who already tended to dwell on low moods had more depression and stress at both follow-ups. And those who dwelt most on the earthquake in the first 10 days were still worse off seven weeks later.
You can see it happen in eight minutes. Breaking Free from Low Moods: Powerful Strategies to Reset Your Mind and Energy has the people in a low mood who spent eight minutes either dwelling on their own feelings or thinking about neutral things, such as places and objects. The dwellers came out lower. The others came out lifted. People in a normal mood were unmoved either way. The same article has the ninety-minute walk: adults who walked through a natural setting came back brooding less, with a part of the brain tied to that looping kind of thought gone quieter, while those who walked along a city street showed neither change.
Dwelling feels like working the problem out. It mostly keeps the problem company. A thought on its third lap has nothing new to tell you. When you notice it coming round again, do something with your body or your hands, or write the problem down with one next step beside it. A walk under trees is a good place to start.
Mindfulness, measured
The claim that ten minutes a day shrinks the brain's alarm centre is too neat. What has been measured is more modest, and still remarkable.
Sixteen people who had never meditated took an eight-week mindfulness course, and their brains were scanned before and after. Compared with 17 people on a waiting list, they gained grey matter in the left hippocampus, a region involved in memory and emotional control, and in several other areas.
Eight weeks. Adult brains. Measurable change. That is what practice looks like. No app subscription was involved. Daniel Goleman and Richard Davidson's sorts the meditation findings that hold from the ones that do not.
To make it stick, tie it to something you already do every day, such as brushing your teeth, so the habit has a cue. And if you want a gentler start, End Your Day Right: How Gratitude Before Sleep Can Help You Rest has what two weeks of gratitude writing did for sleep and blood pressure.
Optimism and a longer life
Optimism goes with a longer life, and the figures are large.
In two long-running groups of American adults, women followed for ten years and men for thirty, optimism was measured at the start. The most optimistic quarter of the women lived 14.9% longer than the least optimistic quarter. The most optimistic women and men had 1.5 and 1.7 times the odds of reaching 85. The link held after health habits such as smoking and exercise were taken into account.
That is a link, not proof that optimism causes the extra years. But optimism can be learned, which makes it worth the effort. Few free things come with extra years attached. 5 Practical Ways to Cultivate a Positive Mindset, linked below, has how far it moves: across 29 tests with more than 3,000 people, exercises raised optimism by a modest amount, and imagining a best possible future worked best. 5 Steps to Manifest Your Dreams with the Law of Attraction has the heart figures: across 229,391 people, optimists had a 35% lower risk of heart attacks, strokes and other heart problems.
The best-known story is Norman Cousins's. He wrote that laughter eased his pain through a long illness. 10 Ways Laughter Is Good for Your Health and Happiness tells it honestly, including the critic who suggested his illness may have eased on its own.
When positivity turns toxic
Positive thinking has a dark side, and it is worth naming. Forced cheer, denying real pain, and pressuring yourself or others to always look on the bright side do harm.
Even chasing happiness can backfire. How Your Thoughts and Emotions Shape Your Body, Mood and Choices has the women who valued being happy most and were less happy when life was calm, and the women nudged to value happiness who enjoyed a cheerful film less, disappointed by their own feelings. Demanding happiness of yourself is a reliable way to spoil it. Russ Harris's is a practical guide to making room for difficult feelings instead of fighting them.
The same goes for the mirror. Daily Affirmations That Work (and the Kind That Backfires) has the classic poster affirmation, which gives a small lift to people who already feel fairly good about themselves, and can make things worse for the people with low self-esteem it is sold to.
And expectation cuts both ways. How Your Thoughts and Emotions Shape Your Body, Mood and Choices, above, has the people shown alarming material about the inaudible low sound from wind turbines, who reported more and stronger symptoms, and the same symptoms when the sound had been switched off without their knowing.
Difficult feelings are information. Fear points at a risk, sadness at a loss, anger at something that crossed a line. Notice them, name them, and then decide what to do. That is the honest version of positive thinking: seeing the situation clearly, and still reaching for the next useful step.
Think carefully
Go back to 2.9013. A precise number, impressive equations, a bestselling idea, and wrong. Beautiful maths, wrong answer. The real findings are less tidy and more useful: repetition rewires, savouring amplifies, reframing helps, eight weeks of practice changes the brain, and optimism goes with longer life.
The way you think does shape the life you live. Just think carefully about the claims.
Tonight, before you sleep, recall one good thing from today and stay with it for longer than feels necessary.
Want to change a thought that's running your day? How Changing Your Thoughts Changes Your Day — how to catch a thought and give it a fair hearing.
Want an outlook that holds up on bad days too? 5 Practical Ways to Cultivate a Positive Mindset — optimism without forced cheer.
Know someone with a "Good vibes only" sign? Send them this, and the story of 2.9013.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional. If low mood has lasted for weeks or you have thoughts of harming yourself, reach out for help today.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
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