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Why the same circle looks smaller among big ones: the Ebbinghaus illusion and size contrast Two identical orange circles, one ringed by big circles and one by small ones, and your eyes insist they differ. That is the Ebbinghaus illusion: your visual… Mind4 min read1 Nov Why a nerve spike is always the same size: the all-or-nothing action potential Every nerve signal in your body is the same size. A feather touch and a hammer blow send identical electrical spikes, so how does the brain tell them apart?… Biology4 min read28 Oct Why still rocks creep upward after you stare at a waterfall: the motion aftereffect Stare at a waterfall, then look at the rocks beside it, and they seem to crawl upward. They go nowhere, yet they move. This is the motion aftereffect, noticed… Mind3 min read26 Oct Why you hear a note that isn't there: the missing fundamental Play only 220, 330 and 440 hertz and most people hear a note at 110 hertz — a frequency that is not in the sound at all. This is the missing fundamental: the… Music & Sound5 min read23 Oct Why 'The old man the boat' stops you cold: garden-path sentences and a brain that guesses Read "The old man the boat." and your brain probably crashes at the fifth word. It guessed "the old man" was one person and waited for a verb that never came… Language4 min read20 Oct Why a dot vanishes when you look away from it: the blind spot where the optic nerve exits Close one eye, stare at a cross, and a dot a hand's width away simply vanishes. That is your blind spot: the place where the optic nerve leaves each eye, with… Mind4 min read19 Oct Why a blink of blank screen hides big changes: change blindness Show someone two nearly identical pictures with a blink of blank screen between them, and a large change can stay hidden for many seconds. This is change… Mind4 min read12 Oct Why “The old man the boat” reads as broken: garden-path sentences Read this: The old man the boat. If it stalled you at the end, your brain did exactly what it always does: it guessed ahead and lost the bet. A garden-path… Language4 min read7 Oct Why you can't ignore the word and name the colour: the Stroop effect Read the word, then name its ink colour: you can't turn reading off. In 1886 Cattell noticed that people read words faster than they name colours, and in 1935… Mind4 min read6 Oct Why the same sound is a b to English ears and a p to Spanish ears Say "bat" and "pat". The only physical difference is a tiny delay between your lips opening and your vocal cords buzzing, about 12 milliseconds for an English… Language3 min read4 Oct Why you hear bass from a speaker too small to make it: the missing fundamental Your phone speaker is far too small to produce a deep bass note, yet you still hear the bass. The trick is that pitch is not a frequency in the air. It is a… Music & Sound3 min read3 Oct Every eye has a hole in its vision, and your brain paints over it Every one of your eyes has a hole in its vision, about ten Moons wide, and you have never seen it. It is where the optic nerve leaves the retina, a patch with… Mind3 min read3 Oct