HOW TO USE THIS GUIDE

You are holding a map of your own head.

Every entry in this guide describes one cognitive bias: a mental
shortcut your brain takes automatically, thousands of times a day,
without asking your permission. These shortcuts aren't defects.
They exist because a brain that weighed every decision from
scratch would burn through its energy budget before breakfast.
Most of the time they serve you well. But each shortcut has a
blind spot - a predictable situation where it produces the wrong
answer with total confidence. Marketers, negotiators, media and
apps know these blind spots by name. After this guide, so will you.

Three honest warnings before you start.

First: you cannot delete a bias. Reading about loss aversion does
not switch it off, any more than reading about optical illusions
makes them disappear. What you CAN do is learn to recognize the
situations where each bias fires, and build small habits - the
"YOUR DEFENSE" section of every entry - that catch it before it
spends your money or damages your relationships.

Second: you will recognize other people in these pages long before
you recognize yourself. That, too, is a bias (#036, the Bias Blind
Spot). When an entry makes you think of someone else, that's your
cue to read it twice.

Third: this is a field guide, not a textbook. Definitions follow
the standard psychology literature on cognitive biases (the
Cognitive Bias Codex tradition), and researchers are named only
where the attribution is settled. Where science is still arguing,
the entry says so. You won't find invented statistics here - a
guide about flawed thinking shouldn't add to it.

Read it front to back, or open it anywhere. Each entry stands
alone: what the bias is, what's happening in your head, where
you'll meet it this week, what it costs you, and how to fight
back. Cross-references (#NNN) point you to its relatives.

One bias a day keeps the manipulation away.