Ten Cognitive Biases and Where You'll Meet Them Today

Biases aren't stupidity — they're shortcuts that misfire

Your brain runs on shortcuts. It has to: you make thousands of judgements a day and you can't reason each one from scratch, so it uses fast rules of thumb that are right often enough to be worth it. A cognitive bias is one of those shortcuts firing in a situation where it produces a predictable, systematic error.

The key word is systematic. These aren't random mistakes — they push in a known direction, which is exactly why they can be exploited by advertisers, apps, scammers and anyone selling you something, and why knowing them is a form of self-defence. You will not stop having them; even people who study them for a living fall for them. What you can do is recognise the situations where they show up and slow down for those.

Here are ten you'll meet before the end of today, each with what it is, where you'll meet it, and the one move that catches it.

The ten

1. Confirmation bias — you look for what you already believe

You notice, remember and trust evidence that fits what you already think, and quietly ignore the rest. It's the master bias — it makes every other one worse. Where today: your feed, which learned what you agree with and now feeds you a world made of it; any argument where you "did your research" and found exactly what you hoped. Catch it: actively go looking for the strongest case against your view. If you can't state it fairly, you don't understand your own position yet.

2. Anchoring — the first number sticks

The first number you see drags every judgement after it, even when it's arbitrary. Where today: the "was £80, now £30" price tag (the £80 is the anchor, and it's there to make £30 feel generous); the first salary figure named in a negotiation; "RRP" on anything. Catch it: decide what something is worth to you before you look at their number. (This is the whole reason SO-11 says know your own number first.)

3. Availability — whatever comes to mind easily feels common

You judge how likely something is by how easily examples spring to mind — and vivid, recent, heavily reported things spring up fastest, regardless of their real frequency. Where today: fearing the dramatic rare event (a plane, a shark) over the boring common one (the car ride there); thinking a trend is everywhere because your feed shows it constantly. Catch it: ask "how would I actually know the rate?" — and reach for the base rate (bias 9), not the vivid example.

4. Survivorship bias — you only see the winners

You judge from the things that made it through, because the failures are invisible — they didn't survive to be counted. Where today: "drop out, these founders did!" (you never hear from the thousands who dropped out and it went badly); studying the routines of successful people as if they caused the success. Catch it: ask "where are the ones this didn't work for, and would I ever have heard from them?"

5. Sunk cost fallacy — throwing good after bad

You keep investing in something because of what you've already put in, even when quitting is clearly better. But the past spending is gone either way — only the future matters. Where today: finishing a bad film/series/book "because I've come this far"; staying in a course, project or relationship for the time already sunk. Catch it: ask "knowing what I know now, would I start this today?" If no, the prior cost is irrelevant.

6. Dunning–Kruger — too unskilled to see you're unskilled

When you're bad at something, the very skills you'd need to judge that you're bad are the ones you're missing — so beginners overrate themselves and genuine experts, aware of all they don't know, often underrate themselves. Where today: the confident hot take on a field someone learned about yesterday; your own certainty right after starting something new. Catch it: early confidence is a warning light, not a green one. Ask "what would an actual expert say I'm missing?"

7. Framing & loss aversion — how it's worded changes the choice

The same fact framed as a loss hits about twice as hard as it does framed as a gain, so wording moves decisions even when the substance is identical. "90% survive" and "10% die" are the same number and land completely differently. Where today: "don't miss out!", "only 2 left!", limited-time everything — all built on the pain of losing. Catch it: restate the choice in the opposite frame (gain ↔ loss) and see if your answer changes. If it does, the frame was driving, not the facts.

8. Hindsight bias — "I knew it all along"

Once you know how something turned out, it feels like it was obvious and predictable — so you overrate how knowable it was and learn the wrong lessons. Where today: every post-match, post-election, post-crash take explaining why it was inevitable; judging a past decision by its outcome instead of by what was knowable at the time. Catch it: judge decisions by the information available when they were made, not by how they landed.

9. Base-rate neglect — ignoring how common something is

You focus on the specific, vivid detail and forget the background rate that should anchor the whole judgement. Where today: a test that's "95% accurate" for a rare condition still throwing mostly false alarms, because the condition is rare — and almost everyone gets this wrong; judging someone by a stereotype instead of what's actually common. Catch it: always ask "out of how many?" — start from the base rate, then adjust for the specifics.

10. Fundamental attribution error — them = character, me = circumstances

When someone else messes up, you blame who they are ("careless", "rude"). When you do the same thing, you blame the situation ("I was rushed"). Same act, two different explanations, and the double standard runs one way. Where today: the driver who cut in is a jerk (you were just merging late); the one late reply means they don't care (your late replies were because you were busy). Catch it: ask "what situation could put a reasonable person in this spot?" before you reach for their character.

Why knowing them isn't the same as beating them

The uncomfortable research finding: simply knowing about a bias barely reduces it in the moment. Awareness alone isn't the fix, because these fire automatically, below the level you notice.

What actually helps is narrower and more useful: recognising the situations where a bias reliably shows up, and building a check into those specific moments. You can't be vigilant against all ten all day. You can learn that "was £80, now £30" is an anchor, that a strong emotional pull to share is confirmation bias hunting, that "I've come this far" is sunk cost — and slow down for those. Defence is situational, not general.

What this means for you

• Biases push in a known direction, which is why they're exploitable — and why naming them is armour.
• Confirmation bias is the amplifier. Deliberately seek the best counter-argument; it dampens the rest.
• Any "was X, now Y" is an anchor. Decide your own number before you see theirs.
• You only ever see the survivors. Ask where the failures went.
• The past cost is gone. Decide from here, on the future alone.
• Knowing ≠ beating. Build the check into the situation, not into a vague intention to be rational.

Try it: catch ten biases in your own week (30 min)

Biases are easiest to see in yourself in hindsight — start there, then you'll catch them live.

1. Go back over the last week — your decisions, purchases, arguments, scrolls, judgements of people.
2. For each of the ten, find one real moment it showed up (in you, or in something you consumed):

BIAS: ..........................................................
THE MOMENT: (what actually happened) ...........................
WHICH DIRECTION IT PUSHED ME: ..................................
THE CATCH I'D USE NEXT TIME: ...................................

3. Pick the one that costs you most often and write the specific situation-trigger you'll watch for.

✅ Finish check: all ten matched to a real moment from your own week, each with the catch, and one named as your personal worst offender with its trigger.

Summary card

• A bias is a mental shortcut misfiring in a systematic, exploitable direction.
• 1. Confirmation — seek the best counter-case. 2. Anchoring — your number before theirs.
• 3. Availability — easy-to-recall ≠ common. 4. Survivorship — where are the failures?
• 5. Sunk cost — would I start this today? 6. Dunning–Kruger — early confidence is a warning.
• 7. Framing/loss aversion — flip gain↔loss, does the answer change? 8. Hindsight — judge by what was knowable then.
• 9. Base-rate neglect — "out of how many?" 10. Attribution error — what situation, not what character?
• Knowing isn't beating. Build checks into the situations where each one shows up.

Sources

1. Kahneman, D. — Thinking, Fast and Slow, 2011
2. Tversky, A. & Kahneman, D. — Judgment under Uncertainty, 1974
3. Ariely, D. — Predictably Irrational, 2008
4. Thaler, R. & Sunstein, C. — Nudge, 2008

Next lesson: DT-05 — How to Read a Scientific Paper (L3) Related: DT-08 Logical Fallacies · DT-03 Correlation Is Not Causation · DT-09 Verifying a Source · MN-10 The Anatomy of a Scam Path: Hard to Fool — 5/6