Image credits: Canva AI
Once we’ve said “three days”, every adjustment after that is a small tweak around three days instead of a real rethink. Planning points us toward the future, so we focus on the details of this project and forget how similar ones went. Psychologists call this the inside view. Then we anchor on our first number.
The business world isn’t immune either: more than 80% of start-ups miss their initial market-share targets, a number some researchers link to this same bias. Nobody is forgetting the task or running out of hours. You know what needs to be done, and you know roughly how long it took last time. You still plan for a faster version of yourself. Students say they finish about two-thirds of their assignments later than they expected. Home renovations run over budget so often that we barely blink anymore. And big projects like the Sydney Opera House ran years late. This only happens when we estimate our own work. Outside observers tend to guess longer timelines than the person doing the task. That points to the planner, not the task. Image credit: Canva AI Psychologists point to a few causes, and laziness isn’t one of them.
In one survey of Canadian taxpayers , people expected to mail their forms about a week earlier than usual, then sent them at the same time as always.
Daniel Kahneman and Amos Tversky named it in 1979, and Roger Buehler and colleagues later tested it in a study. Because the cycle feeds itself. Because something unexpected is always on its way, then add a little breathing room,.
It was called the “ Planning Fallacy ,” published by ResearchGate in December 2010. “When do I want to finish?” and “When will I actually finish?” feel like the same question, but they aren’t. In one study, published in the Journal of Personality and Social Psychology, called Exploring the “Planning Fallacy”: Why people underestimate their task completion times , incoming university students were expected to outperform about 84% of their classmates. If you say “three months” in a room where someone else says “six weeks,” the six-week project is the one that gets approved. Next time you catch yourself saying “three days, easy”, check how long it took last time.
The planning fallacy is the stubborn belief that this project will go as planned, even though most similar projects have run late or failed. Many people make mistakes when attempting a new task. The planning fallacy is a cognitive bias in which people underestimate the time, cost and risk of completing a future task, even when they know that similar tasks have run over in the past. The bias applies mainly to our own plans: when we forecast how long our own work will take, we tend to be too optimistic, while outside observers usually guess longer timelines. It affects individuals, teams and organisations alike, from school assignments to home renovations and large construction projects. Doing a task many times gives us plenty of evidence about how long it takes, yet that evidence rarely changes the next estimate. Our future behaviour tends to match our past behaviour, and sometimes a task takes even longer than we remember. We focus on the details of the task in front of us, imagine the best case, and set our past experience aside. Every new plan seems sensible on paper, yet the same discrepancy between plan and reality reappears. Our wish to be done early quietly slips into the forecast, and we end up guessing with our fingers crossed. We’re also wired to look on the bright side, especially about ourselves. That can’t be true for everyone. When we plan, we picture the smooth version and skip the potholes. At work, a realistic estimate can sound like a lack of ambition. Many planners shave their numbers on purpose, to get a green light or to keep the boss happy. Over time, the most optimistic number wins, and everyone learns to play along. We miss the deadline, stay optimistic and plan the same way next time. Simply knowing about the planning fallacy doesn’t break it either. Your gut will still say this time is different. Missed deadlines strain friendships and can make you look unreliable at work. Under-budgeted projects end up rushed and lower in quality. Day to day, it leaves you feeling behind, always catching up on a schedule you set yourself. Image credits: Canva AI A few habits can help. Start by looking back. Check how long similar tasks actually took you or how long they took other people, and let that set the estimate instead of your mood. Researchers call this the outside view, and using it has been shown to cut time and cost overruns on everything from personal tasks to big construction projects. Get specific about when and where you’ll start. In a Dutch study, people who decided the time and place they would write their paper made more realistic plans, and they didn’t lose any confidence doing it. Break big jobs into small pieces. We’re surprisingly good at estimating small tasks, and when we’re wrong, we usually overestimate, which is the safer mistake. Our minds protect our optimism and try to please the people around us, which is why we lowball our own timelines. Once you see these causes, you can plan around them. You use AI every day. Now get your AI Quotient. Take the AIQ test Get the latest Lifestyle News and more. Download the TOI app.
