The Planning Fallacy

Posted in Principles

We tend to be overly optimistic about our ability to finish tasks on time. We consistently believe the future will unfold as planned, and we rarely leave sufficient time to meet key deadlines. This phenomenon is called the planning fallacy, and can make it difficult for us to complete seemingly simple tasks like being on time for a meeting, but it can also make it hard to do more important things like meeting the application deadlines for college scholarships.

Unbelievably, the effects of planning fallacy hold even when we are warned about them and encouraged to make plans for worst-case scenarios. In one study, college students were asked to give their best, most optimistic, and most pessimistic estimates of how long it would take them to complete their senior thesis. The result? Students’ actual completion time was a remarkable 21.6 days longer than their best estimate (55.5 days to 33.9 days) and less than half of students (48.7%) completed their thesis by even their most pessimistic estimates. Similar results have been found in a variety of other settings, including writing software programs, completing tax forms, and even crafting origami.

To combat the planning fallacy, it helps to make salient the amount of effort involved in completing a task. This can be done by relating it to a similar past experiences or simply by informing people of the average time it takes to complete the task.

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