Bluff
Twelve statements about your body and brain. Half are true, half are plausible lies we made up. Can you tell which is which? Every card reveals the real, sourced fact. A fresh deck every day.
Card 1 of 12 Streak 0
Real fact, or a fake we invented? Your call. (Keys: R / F)
0/ 12
Spotting a fake is a real skill. The lies here weren't random, each one sounds true because it fits something you already half-believe (we only use 10% of our brains; cracking knuckles wrecks them; you can feel a stare). That's exactly how a myth survives: it rhymes with your intuition. The fix isn't being cleverer, it's the reflex you just practised, asking “wait, who actually checked that?” Every real fact here has a source below. The fakes never did.
Our sources
// every fact this game reveals was checked before it went up
✓ The 'visual ear' (visually-evoked auditory response) is real: about 21% of people report hearing a faint sound when watching a silent GIF of motion, and the phantom sound measurably interferes with detecting real faint sounds.
, Fassnidge & Freeman, 'Sounds from seeing silent motion,' Cortex, 2018 (N>4,000, ~21%)
✓ The 'psychic staring effect' fails under proper testing, participants perform at chance, not ~90%; Titchener found chance-level results in 1898, and later above-chance claims were shown to be an artefact of non-random staring sequences people could implicitly learn.
, Titchener, Science, 1898; Marks & Colwell, 'The Psychic Staring Effect: An Artifact of Pseudo Randomization,' Skeptical Inquirer, 2000
✓ You can't tickle yourself because the cerebellum predicts the sensory consequences of your own movement (via an efference copy / forward model) and attenuates the resulting touch; self-produced touch feels measurably weaker than identical external touch.
, Blakemore, Wolpert & Frith, 'Central cancellation of self-produced tickle sensation,' Nature Neuroscience, 1998
✓ The claim that humans use only 10% of their brains is a myth: functional imaging shows virtually all of the brain is active, and no large dormant region exists; even simple tasks engage widespread areas.
, Beyerstein, in 'Mind Myths' (1999); Boyd, 'Do people only use 10 percent of their brains?', Scientific American, 2008
✓ The 'doorway effect' is real: people forget an intention more after passing through a doorway than after moving the same distance within one room, in both real and virtual environments, the brain treats a threshold as an 'event boundary.'
, Radvansky, Krawietz & Tamplin, 'Walking through doorways causes forgetting,' Quarterly Journal of Experimental Psychology, 2011
✓ Habitual knuckle-cracking has not been shown to cause arthritis: controlled studies find no association, and Donald Unger cracked only his left hand for ~60 years with no difference between his hands. The 'pop' is a cavitation event in the joint fluid.
, Deweber et al., 'Knuckle cracking and hand osteoarthritis,' J. Am. Board Fam. Med., 2011; Unger, Arthritis & Rheumatism, 1998 (Ig Nobel, 2009)
✓ Shown a round shape and a spiky shape, ~95% of people match the round one to 'bouba' and the spiky one to 'kiki'; first shown by Köhler in 1929, and a 2022 study found the effect in 17 of 25 languages tested.
, Ramachandran & Hubbard, 2001; Ćwiek et al., Phil. Trans. R. Soc. B, 2022
✓ Aphantasia is objectively measurable, not just a difference in describing imagination: imagining a bright object makes typical pupils constrict involuntarily (an imagery pupillary light response), while aphantasic pupils show little or no such response, a reflex that can't be faked.
, Kay, Keogh, Andrillon & Pearson, 'The pupillary light response as a physiological index of aphantasia,' eLife, 2022
✓ In Ola Svenson's 1981 study, 93% of the US sample rated themselves in the top 50% for driving skill, impossible for more than about half of any group, and a classic demonstration of the better-than-average effect.
, Svenson, 'Are we all less risky and more skillful than our fellow drivers?', Acta Psychologica, 1981
≈ Infrasound (~19 Hz) does not reliably make people see ghostly figures: the proposed eyeball-resonance mechanism is contested and has not been reliably reproduced, and a 2009 study found suggestibility predicted anomalous experiences better than infrasound; at most it modestly nudges unease.
, Tandy & Lawrence, JSPR, 1998; French et al., 'The Haunt project,' Cortex, 2009
✓ The brain's face-specific response (the N170) fires at around 165 ms for face-like objects, a similar time to real faces, so face pareidolia is handled by early perception, not late reinterpretation.
, Hadjikhani et al., 'Early (N170) activation of face-specific cortex by face-like objects,' NeuroReport, 2009
≈ The Dunning-Kruger effect is not a settled certainty: several reanalyses argue the classic pattern is largely a statistical artefact (regression to the mean plus the better-than-average effect), though its original authors maintain the miscalibration persists.
, Gignac & Zajenkowski, 'The Dunning-Kruger effect is (mostly) a statistical artefact,' Intelligence, 2020
✓ Deck two, REAL: identical twins have different fingerprints; ridge patterns are shaped partly by random mechanical forces in the womb, so genetically identical twins still differ.
, Jain, Prabhakar & Pankanti, 'On the similarity of identical twin fingerprints,' Pattern Recognition, 2002
✓ Deck two, REAL: Roman marine concrete self-heals; lime clasts in the mix react with infiltrating water to precipitate new minerals that fill cracks, a mechanism absent from most modern concrete.
, Seymour et al., 'Hot mixing: Mechanistic insights into the durability of ancient Roman concrete,' Science Advances, 2023
✓ Deck two, FAKE corrected: humans have more than five senses; beyond sight, hearing, smell, taste and touch, we sense balance (vestibular), body position (proprioception), temperature and pain, commonly counted as at least nine.
, Standard sensory neuroscience (e.g. Purves et al., Neuroscience) on modalities beyond the classical five
✓ Deck two, REAL: swearing raises pain tolerance; participants kept a hand submerged in ice water significantly longer while repeating a swear word than a neutral word.
, Stephens, Atkins & Kingston, 'Swearing as a response to pain,' NeuroReport, 2009
✓ Deck two, FAKE corrected: the 'tongue map' of separate taste zones is a myth stemming from a mistranslation of Hänig's 1901 work; all taste qualities are detectable across all taste-bud-bearing regions of the tongue.
, Collings, 'Human taste response as a function of locus on the tongue,' Perception & Psychophysics, 1974; on the mistranslation of Hänig (1901)
✓ Deck two, REAL: open-label placebos work; patients told openly they were receiving an inert placebo still showed significant symptom improvement (e.g. in irritable bowel syndrome and chronic low back pain).
, Kaptchuk et al., 'Placebos without deception,' PLoS ONE, 2010; Carvalho et al., Pain, 2016
✓ Deck two, FAKE corrected: shaving does not make hair grow back thicker, darker or faster; controlled studies dating to 1928 found no change in rate or coarseness, shaving only blunts the tip of existing hair.
, Trotter, 'Hair growth and shaving,' Anatomical Record, 1928; Lynfield & Macwilliams, J. Invest. Dermatol., 1970
✓ Deck two, REAL: pregnancy reshapes the brain; MRI shows reductions in grey matter in social-cognition regions that persist for at least two years and are consistent enough to classify a woman as having been pregnant.
, Hoekzema et al., 'Pregnancy leads to long-lasting changes in human brain structure,' Nature Neuroscience, 2017
✓ Deck two, FAKE corrected: you do not lose most body heat through your head; heat loss is roughly proportional to exposed surface area (the head is about 10%). The myth traces to a flawed cold-exposure interpretation where only the head was uncovered.
, Pretorius et al. on regional heat loss; Vreeman & Carroll, 'Medical myths,' BMJ, 2008
≈ Deck two, REAL: migratory birds appear to sense Earth's magnetic field via light-dependent radical-pair chemistry in cryptochrome proteins in the eye, a leading, well-supported (though still-developing) mechanism for magnetoreception.
, Hore & Mouritsen, 'The radical-pair mechanism of magnetoreception,' Annual Review of Biophysics, 2016
✓ Deck two, FAKE corrected: goldfish do not have a three-second memory; they retain learned associations for weeks to months and can be trained on tasks, disproving the folklore.
, Standard fish-cognition research on goldfish learning and long-term retention
✓ Deck two, FAKE corrected: hair and nails do not keep growing after death; growth requires living, glucose-fed cells. The appearance is caused by skin dehydrating and retracting from nails and stubble.
, Vreeman & Carroll, 'Medical myths even doctors believe,' BMJ, 2007