Overcoming Bias: Planning Fallacy

Via The Guardian, via Chairman Gruber, comes this post from the new-to-me blog, Overcoming Bias. It discusses the research behind a common cognitive bias known as The Planning Fallacy, which is a repeatable, documented error in thinking that apparently explains why we all tend to "underestimate task-completion times."

It's summed up nicely by Gödel, Escher, Bach author Douglas Hofstadter's Law regarding the time it takes to do anything:

It always takes longer than you expect, even when you take Hofstadter's Law into account.

Sounds familiar. From the Overcoming Bias post:

People tend to generate their predictions by thinking about the particular, unique features of the task at hand, and constructing a scenario for how they intend to complete the task - which is just what we usually think of as planning.

[...]

But experiment has shown that the more detailed subjects' visualization, the more optimistic (and less accurate) they become.

Cf: The Optimism Bias.