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Clearer Thinking Team

Planning Fallacy: Definition, Examples and Effects

Updated: Jun 29, 2023

The planning fallacy is a cognitive bias that affects our ability to accurately estimate how long it will take to complete a task. It is a common phenomenon that can lead to missed deadlines, budget overruns, and other problems. In this blog post, we will explore the definition, examples, and effects of the planning fallacy.


Definition: The planning fallacy is a cognitive bias that causes us to underestimate the amount of time it will take to complete a task. There are a number of factors that contribute to the planning fallacy. For example, people often focus on the most optimistic scenario, in which everything goes exactly as planned. They may also forget to account for unexpected interruptions or complications. Furthermore, people may be overly optimistic in their own abilities or fail to consider the full complexity of the task at hand.


Examples: The planning fallacy can be seen in many different scenarios. For example, a student may underestimate the amount of time it will take to complete a research paper, or a business may underestimate the amount of time it will take to launch a new product. In both cases, the task is likely to take longer than expected due to unforeseen complications.


Effects: The effects of the planning fallacy can be far-reaching. Missed deadlines can lead to lost revenue, budget overruns, and other problems. Additionally, the planning fallacy can lead to frustration and disappointment, as tasks take longer than expected and deadlines are not met.


Overall, the planning fallacy is a common cognitive bias that can lead to missed deadlines, budget overruns, and other problems. It is important to be aware of this bias and take steps to mitigate its effects. By taking the time to accurately estimate the amount of time it will take to complete a task, we can avoid the pitfalls of the planning fallacy.


Do you want to expand your knowledge on this topic? Read our full in-depth article on cognitive biases.


Do you have extra 15 minutes today? Take our fun and interactive quiz to learn which of 16 reasoning styles you use, your overall level of rationality, and what you can do now to improve your rationality skills.

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