A Collection of Strange Beliefs, Amusing Deceptions, and Dangerous Delusions

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hidden persuaders (cognitive biases, fallacies, and illusions)

A term used by Geoffrey Dean and Ivan Kelly (2003) to describe affective, perceptual, and cognitive biases or illusions that lead to erroneous beliefs. Examples of hidden persuaders abound. Some of the more important ones are:

ad hoc hypothesis

affect bias

anchoring effect


autokinetic effect

attribution errors

availability error

Barnum effect

backfire effect

bias blind spot

change blindness

Clever Hans phenomenon

clever Linda phenomenon

clustering illusion

cognitive dissonance


cold reading

communal reinforcement



confirmation bias

continued influence effect

experimenter effect

file-drawer effect

Forer effect

gambler's fallacy

halo effect

hindsight bias

hypersensory perception

ideomotor effect

illusion of control

illusion of justice

illusion of skill

illusion of understanding

inattentional blindness

intentionality bias

loss aversion

magical thinking

motivated reasoning

negativity bias



perfect solution fallacy

placebo effect

positive-outcome bias

post hoc reasoning

pragmatic fallacy

proportionality bias

recency bias

regressive fallacy

representativeness error

retrospective falsification

selection bias

selective thinking



single-cause bias/fallacy/illusion

subjective validation

sunk-cost fallacy

testimonials (anecdotal evidence)

Texas-sharpshooter fallacy

wishful thinking.

"Technically these hidden persuaders can be described as ‘statistical artifacts and inferential biases’ (Dean and Kelly 2003: 180)." Dean and Kelly argue that hidden persuaders explain why many astrologers continue to believe in the validity of astrology despite overwhelming evidence that astrology is bunk. Psychologist Terence Hines, who has explored many varieties of hidden persuaders (Hines 2003), blames them for the continued use by psychologists of such instruments as the Rorschach test, despite overwhelming evidence that the test is invalid and useless:

Psychologists continue to believe in the Rorschach for the same reasons that Tarot card readers believe in Tarot cards, that palm readers believe in palm reading, and that astrologers believe in astrology: the well-known cognitive illusions that foster false belief. These include reliance on anecdotal evidence, selective memory for seeming successes, and reinforcement from colleagues. (Hines 2003)

The hidden persuaders originate in quite useful adaptations. Seeing patterns, especially causal patterns, is quite beneficial to our species. Recognizing how data support our beliefs and having others share those beliefs are also beneficial. Drawing inferences quickly may mean the difference between life and death. Having hope, reducing tension caused by conflicting ideas, and even deceiving ourselves can be psychologically advantageous. But all of these positive tendencies can become perverted and lead us into error if we are not careful. Many skeptics have noted that the hidden persuaders sometimes seem to affect people in proportion to their intelligence: the smarter one is the easier it is to develop false beliefs. There are several reasons for this: (1) the hidden persuaders affect everybody to some degree; (2) the smarter one is the easier it is to see patterns, fit data to a hypothesis, and draw inferences; (3) the smarter one is the easier it is to rationalize, i.e., explain away strong evidence contrary to one's belief; and (4) smart people are often arrogant and incorrectly think that they cannot be deceived by others, the data, or themselves. Hidden Persuaders (1957) is also the title of a book by Vance Packard. He chronicled the many methods, some pretty open and obvious, that advertisers use in their quest to manipulate the thoughts and actions of consumers. Packard attempted to expose corporate propaganda as a kind of mind control operation, especially in its use of subliminal messaging. What Dean and Kelly describe are the many ways in which we sell ourselves on ideas by putting up conceptual and perceptual blocks to thinking clearly and fairly about certain subjects.

See also Daniel Kahaneman's Thinking, Fast and Slow for the latest analysis of scientific studies on cognitive biases. See also the archive of links to blog posts on hidden persuaders at Unnatural Acts that can improve your thinking.

further reading

books and articles

Adams, James L. Conceptual Blockbusting: A Guide to Better Ideas 3rd ed. (Perseus Press, 1990).

Alcock, J. (1995) "The Belief Engine," Skeptical Inquirer. 19(3): 255-263.

Alcock, James E. Science and Supernature : a Critical Appraisal of Parapsychology (Buffalo, N.Y.: Prometheus Books, 1990).

Ariely, Dan.  (2008). Predictably Irrational: The Hidden Forces That Shape Our Decisions (HarperCollins).

Bausell, R. Barker. (2007). Snake Oil Science: The Truth about Complementary and Alternative Medicine Oxford.

Browne, M. Neil & Stuart M. Keeley. Asking the Right Questions: A Guide to Critical Thinking (Prentice Hall, 1997).

Burton, Robert. 2008. On Being Certain: Believing You Are Right Even When You're Not. St. Martin's Press.

Carroll, Robert Todd. Becoming a Critical Thinker - A Guide for the New Millennium (Boston: Pearson Custom Publishing, 2000).

Chabris, Christopher and Daniel Simons. 2010. The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us. Crown.

Damer. T. Edward. Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments 4th edition (Wadsworth Pub Co, 2001).

Dawes, Robyn M. Everyday Irrationality: How Pseudo-Scientists, Lunatics, and the Rest of Us Systematically Fail to Think Rationally (Westview Press 2003).

Dean, Geoffrey and Ivan Kelly. "Is Astrology Relevant to Consciousness and Psi? Journal of Consciousness Studies. Volume 10, No. 6-7, June-July 2003.

Dean, Geoffrey, Ivan W. Kelly, and Arthur Mather. "Undeceiving Ourselves," in The Skeptic Encyclopedia of Pseudoscience, eds. Michael Shermer and Pat Linse (ABC-CLIO 2002).

Frazier, Kendrick, ed. Paranormal Borderlands of Science (Amherst, N.Y.: Prometheus Books, 1991).

Gardner, Martin. Fads and Fallacies in the Name of Science (New York: Dover Publications, Inc., 1957), 

Gardner, Martin. Science: Good, Bad and Bogus (Buffalo, N.Y.: Prometheus Books, 1981).

Giere, Ronald, Understanding Scientific Reasoning, 4th ed, (New York, Holt Rinehart, Winston: 1998).

Gilovich, Thomas. How We Know What Isn't So: The Fallibility of Human Reason in Everyday Life (New York: The Free Press, 1993).

Groopman, Jerome. M.D. 2007. How Doctors Think. Houghton Mifflin. My review of this book is here.

Hall, Harriet A. "Wired to the Kitchen Sink - Studying Weird Claims for Fun and Profit," Skeptical Inquirer. May/June 2003.

Hines, Terence. "A Clear, Sharp View of the Fuzzy Inkblot Test," Skeptical Inquirer, September/October 2003. (A review of What's Wrong with the Rorschach? by James M. Wood, M. Teresa Nezworski, Scott O. Lilienfeld, and Howard N. Garb (Jossey-Bass 2003).

Hines, Terence. Pseudoscience and the Paranormal (Buffalo, NY: Prometheus Books, 2003).

Hyman, Ray. The Elusive Quarry : a Scientific Appraisal of Psychical Research (Buffalo, N.Y.: Prometheus Books, 1989).

Hyman Ray. "Why and When Are Smart People Stupid?" in Sternberg 2002.

Kahneman, Daniel. Paul Slovic, and Amos Tversky. eds. 1982. Judgment Under Uncertainty: Heuristics and Biases Cambridge University Press.

Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life, 8th edition (Wadsworth, 1997).

Kahneman, Daniel. Thinking, Fast and Slow (Kindle 2011) . Book review.

Kida, Thomas. 2006. Don't Believe Everything You Think: The 6 Basic Mistakes We Make in Thinking. Prometheus.

Kourany, Janet A. Scientific Knowledge: Basic Issues in the Philosophy of Science, 2nd edition (Belmont: Wadsworth Publishing Co., 1998).

Levine, Robert. 2003. The Power of Persuasion - How We're Bought and Sold. John Wiley & Sons.

Moore, Brooke Noel. Critical Thinking (Mayfield Publishing Company, 2000).

Neher, Andrew. The Psychology of Transcendence  (Prentice-Hall 1980).

Park, Robert L. Voodoo Science: the Road from Foolishness to Fraud (Oxford University Press, 2000).

Pickover, Clifford A. The Girl Who Gave Birth to Rabbits : A True Medical Mystery (Prometheus, 2000).

Randi, James. Flim-Flam! Psychics, ESP, Unicorns, and Other Delusions (Buffalo, New York: Prometheus Books, 1982).

Reed, Graham. The Psychology of Anomalous Experience : A Cognitive Approach (Buffalo, NY: Prometheus Books, 1988).

Sagan, Carl. The Demon-Haunted World - Science as a Candle in the Dark (New York: Random House, 1995).

Schick, Jr., Theodore and Lewis Vaughn, How to Think About Weird Things 5th ed. (McGraw-Hill, 2001), 

Seckel, Al. (2006). Incredible Visual Illusions. Arcturus Publishing, Ltd.

Shermer, Michael. The Borderlands of Science: Where Sense Meets Nonsense (Oxford University Press, 2001).

Shermer, Michael. Why People Believe Weird Things: Pseudoscience, Superstition, and Other Confusions of Our Time 2nd revised edition (Owl Books 2002).

Shermer, Michael. "Why Smart People Believe Weird Things," Skeptic. Vol. 10 No. 2, 2003, pp. 62-73.

Skinner, B. F. 'Superstition' in the Pigeon. Indiana University First published in Journal of Experimental Psychology, 38, 168-172.

Stanovich, Keith E., How to Think Straight About Psychology, 5th edition (Addison-Wesley, 1997).

Stenger, Victor J. Physics and Psychics: the Search for a World Beyond the Senses (Buffalo, N.Y.: Prometheus Books, 1990).

Sternberg, Robert J. ed. Why Smart people Can Be So Stupid. (Yale University Press 2002).

Sutherland, Stuart. (2007). Irrationality. 2rev edition (Pinter & Martin Ltd).

Taleb, Nassim Nicholas. 2007.  The Black Swan: The Impact of the Highly Improbable. Random House.

Van Hecke, Madeleine L. (2007). Blind Spots: Why Smart People Do Dumb Things. Prometheus.

Vaughn, Lewis. 2007. The Power of Critical Thinking: Effective Reasoning About Ordinary and Extraordinary Claims. 2nd. ed. Oxford University Press.

Vyse, Stuart A. Believing in Magic: The Psychology of Superstition (Oxford University Press 2000).

Wiseman, Richard. Deception & Self-Deception: Investigating Psychics (Prometheus Books, 1997).

Zusne, Leonard & Warren Jones. Anomalistic Psychology: A Study of Magical Thinking (Lawrence Erlbaum Association, 1990).


Unnatural Acts: A follow-up to my book Unnatural Acts: Critical Thinking, Skepticism and Science Exposed! The blog offers irregular postings about biases, fallacies, and illusions.

A Visual Study Guide to Cognitive Biases Eric Fernandez

You're Not So Smart David McRaneyLast updated 14-Dec-2014

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