---
title: Cognitive biases and heuristics
url: https://propagandaarchive.org/learn/cognitive-biases/
description: 'Heuristics are rules of thumb: judging how likely something is by how easily examples come to mind, starting from the first number heard, trusting what…'
section: Learn
---

![Illustration: a redacted Cold War intelligence-dossier collage centred on a world map of influence operations, with the U.S. Capitol among the evidence.](https://propagandaarchive.org/static/generated/hero-home.jpg)

[Learn](https://propagandaarchive.org/learn/)

# Cognitive biases and heuristics

*Part of the [Learn](https://propagandaarchive.org/learn/) library. Mental shortcuts everyone uses to judge quickly, and the predictable errors they produce.*

Heuristics are rules of thumb: judging how likely something is by how easily examples come to mind, starting from the first number heard, trusting what feels familiar. They usually serve people well, which is why they persist. They also fail in systematic ways, and messages built to trigger those failures can move judgments without adding any evidence. These pages cover the best-studied shortcuts and biases and what happens when political messaging leans on them.

Each page carries an evidence rating explained in [How we rate the evidence](https://propagandaarchive.org/learn/evidence-ratings/).

## Pages

- [Anchoring](https://propagandaarchive.org/learn/anchoring/) — Anchoring (evidence: strong). The first number heard pulls later estimates toward it.
- [Availability heuristic](https://propagandaarchive.org/learn/availability-heuristic/) — Availability heuristic (evidence: moderate). What comes to mind easily feels common and likely.
- [Base-rate neglect](https://propagandaarchive.org/learn/base-rate-neglect/) — Base-rate neglect (evidence: strong). A vivid case outweighs how common something actually is.
- [Confirmation bias](https://propagandaarchive.org/learn/confirmation-bias/) — Confirmation bias (evidence: strong). Seeking and reading evidence in ways that fit existing beliefs.
- [Continued influence effect](https://propagandaarchive.org/learn/continued-influence-effect/) — Continued influence effect (evidence: strong). A corrected falsehood keeps shaping judgment.
- [Framing effect](https://propagandaarchive.org/learn/framing-effect/) — Framing effect (evidence: strong). The same facts presented differently change the choice.
- [Illusory truth effect](https://propagandaarchive.org/learn/illusory-truth-effect/) — Illusory truth effect (evidence: strong). Repetition makes claims feel true.
- [Motivated reasoning](https://propagandaarchive.org/learn/motivated-reasoning/) — Motivated reasoning (evidence: moderate). Holding welcome and unwelcome evidence to different standards.
- [Negativity bias](https://propagandaarchive.org/learn/negativity-bias/) — Negativity bias (evidence: strong). Bad news and threats weigh more than good news of the same size.
- [Priming](https://propagandaarchive.org/learn/priming/) — Priming (evidence: mixed). Which priming findings held up, and which did not.

## Related

- [Learn](https://propagandaarchive.org/learn/)
- [How we rate the evidence](https://propagandaarchive.org/learn/evidence-ratings/)
- [Anchoring](https://propagandaarchive.org/learn/anchoring/)
- [Availability heuristic](https://propagandaarchive.org/learn/availability-heuristic/)
- [Base-rate neglect](https://propagandaarchive.org/learn/base-rate-neglect/)
- [Confirmation bias](https://propagandaarchive.org/learn/confirmation-bias/)
- [Continued influence effect](https://propagandaarchive.org/learn/continued-influence-effect/)
- [Framing effect](https://propagandaarchive.org/learn/framing-effect/)
- [Illusory truth effect](https://propagandaarchive.org/learn/illusory-truth-effect/)
- [Motivated reasoning](https://propagandaarchive.org/learn/motivated-reasoning/)
- [Negativity bias](https://propagandaarchive.org/learn/negativity-bias/)
- [Priming](https://propagandaarchive.org/learn/priming/)