The blink: a painting that changes while the eyes are closed

Why you miss a change made while you blink

Without any interruption, a sudden change leaps out. When Daniel Simons and his colleagues swapped a photograph instantly, with nothing between the two versions, people noticed 97% of the objects that appeared or vanished and 92% of the colour changes.¹

What helps them is the suddenness itself: the change makes a small flicker on the retina, which pulls the eyes and the attention to its place. A blink covers it. In blinks made on request, the lid comes down in about 76 milliseconds, the eye stays fully shut for about 58 more and reopens over about 438, as Kwon and colleagues measured with a camera filming 600 frames a second.² In voluntary blinks the pupil stays covered for between 121 and 248 milliseconds, according to measurements made in 1981 on three people.³

In 2000, Kevin O’Regan, Heiner Deubel, James Clark and Ronald Rensink did with lab equipment what this page does with a camera: an eye tracker read 400 times a second swapped the photograph on the screen in the middle of a blink. When people were looking straight at the spot that changed, they missed it more than 40% of the time. When their gaze was 2–10 degrees away (a fist held at arm’s length covers about 10 degrees), they noticed only about one change in 10.⁴

The grey blank does the same without a camera. In the 1997 experiment by Rensink, O’Regan and Clark, two versions of a photograph alternated with 80 milliseconds of grey between them. To find a change to an object that people mentioned when describing the scene, they needed on average 7.3 alternations (4.7 seconds); for one that nobody mentioned, 17.1 (10.9 seconds). Without the grey, 1.4 alternations were enough, under a second.⁵

Their conclusion: to see a change, your attention has to be on the object at the moment it changes.⁵

How long you spend blinking without knowing

People blink on average 17 times a minute at rest, 26 times while talking and 4.5 times while reading aloud. That is what Anna Rita Bentivoglio and her colleagues counted when they filmed 150 people who did not know what was being measured.⁶

The sum for a day: 16 waking hours at the resting rate make about 16,000 blinks. At 165 milliseconds each, the average length of a blink measured by Yang, Intoy and Rucci with an eye tracker,⁷ that adds up to about 45 minutes of blinking, or about 4.7% of waking time. At the rate for reading aloud it would be four times less; at the rate of a conversation, half as much again.

And yet the world does not go dark 16,000 times a day. Volkmann, Riggs and Moore lit the retina in a way that bypassed the eyelids, and sensitivity still dropped during voluntary blinks: the loss comes from the nervous system, and the authors suggest it as part of the reason most blinks go unnoticed.⁸ In 2005 Davina Bristow and colleagues showed with functional MRI that a blink lowers activity in the visual cortex and in parts of the parietal and prefrontal cortex that earlier studies had linked to awareness of changes around us.⁹

The blink as a unit of time

In Romanian, the word for a moment, clipă, comes from the verb a clipi, to blink, and once meant a blink itself. It is not the only language that measured the shortest stretch of time by the one moment it cannot see.

• Romanianclipăfrom a clipi, “to blink”; hence într-o clipită, “in a little blink”DEX / MDA2, dexonline
• Russianмгновение mgnovéniefrom mgnut’, “to blink”; related to mig, “instant”, also in BulgarianVasmer
• Polishw mgnieniu oka“in the blink of an eye”: mgnienie is from mgnąć, “to blink”SJP PWN
• Czechokamžikmoment; mžik on its own means both “a blink” and “a moment”SSJČ
• Slovene, Croatian, Serbiantrenutek · trenutakfrom treniti / trenuti, “to blink”; the word first meant a blink itselfSnoj, Slovenski etimološki slovar
• Hungarianpillanatfrom pillanik: “the eyelid suddenly closes and opens”Új magyar etimológiai szótár
• GermanAugenblick“the glance of an eye”, originally its gleam; Dutch has its own ogenblik, and Danish, Swedish, Norwegian and Icelandic borrowed it from Low GermanDWDS (Pfeifer)
• Englishin the twinkling of an eyetwinkle is from Old English twinclian, to shut and open the eyes quicklyEtymonline
• Sanskritनिमेष nimeṣaa blink, and a unit of time in the old Indian lists (its length differs from text to text)Monier-Williams
• Chinese瞬间 shùnjiān瞬 originally means “to blink”; Japanese writes the same word 瞬間, shunkan汉典 zdic
• Hebrewכהרף עין keheref ʿayin“as a flick of the eyelid”; attested in the Jerusalem TalmudBen-Yehuda
• Arabicطرفة عين ṭarfat ʿayn“a wink of the eye”: one closing of the eyelidsLane, Arabic-English Lexicon
• Turkishgöz açıp kapayıncaya kadar“until one opens and closes the eye”: very quicklyTDK

The list has 13 expressions from 11 different roots and 5 language families. Not all of them say “blink” exactly: German Augenblick and its northern relatives mean “the glance of an eye”. And many languages named the moment after something else: Latin momentum comes from movement, instant from “standing near”, Greek στιγμή means a prick, a point, and Italian attimo comes from the atom.

The atom and the blink meet in a single verse. Writing to the Corinthians in Greek, Paul has ἐν ἀτόμῳ, ἐν ῥιπῇ ὀφθαλμοῦ, “in an atom, in a throw of the eye”; Italian attimo descends from Late Latin in atomo, a copy of this Greek phrase. The King James Bible gives it as “In a moment, in the twinkling of an eye, at the last trump”, and the verse ends: “we shall be changed.”

The only blinks you will ever see

You cannot watch yourself blink in a mirror: that is exactly when your eyes are shut. A camera can see your blinks; you never will.

Other people’s, though, you can. Next time you talk with someone you love, look at their eyes. While they talk, you will see them blink about 26 times a minute. Each time, the light goes out for them for a split second and comes back, and they almost never notice. You do.

How the experiment works and what it rests on

The painting has 26 elements and changes 28 times (the sky passes through dusk before night). The order is different every time. 22 changes are hidden: in your blinks with the camera, or in a 150-millisecond grey blank without it. 6 happen with your eyes open, one in each sixth of the experiment, for comparison. Without the camera, another 7 grey blanks hide nothing, so that a blank never announces a change. With the camera, if you do not blink for 5 seconds, the next change is hidden in a grey blank instead, and the result counts those separately. The stars and the moon appear only once the sky has started to darken, and the birds leave before it does; the small changes (stars, birds, smoke, path) are never used for comparison.

A press counts as "I saw it" if it comes between 0.2 and 2 seconds after a change (anything faster is not a reaction). A press made at random can also land in that window, which is why the page counts separately the presses made when nothing had changed.

With the camera, a face landmark model (Google’s MediaPipe Face Landmarker, Apache 2.0 licence) runs on your device and gives, for each eye, a measure of how closed it is. The painting changes when both eyes pass a threshold that adjusts to how your open eyes look. The camera image is not shown, recorded or sent anywhere.

A camera is not as precise as lab equipment. Its image reaches the page with a small delay, so some changes may land as the lid is already lifting, and a downward glance can look like a blink. Your result is a personal trial, less precise than the measurements in the studies above.

The sums in the chapter on blinking combine a rate measured on spontaneous blinks⁶ with a length measured on blinks made on a signal;⁷ 16 waking hours is an assumption.

Sources

1. Simons, D. J., Franconeri, S. L., & Reimer, R. L. (2000). Change blindness in the absence of a visual disruption. Perception, 29(10), 1143–1154. doi.org/10.1068/p3104
2. Kwon, K.-A., Shipley, R. J., Edirisinghe, M., et al. (2013). High-speed camera characterization of voluntary eye blinking kinematics. Journal of the Royal Society Interface, 10, 20130227. doi.org/10.1098/rsif.2013.0227
3. Riggs, L. A., Volkmann, F. C., & Moore, R. K. (1981). Suppression of the blackout due to blinks. Vision Research, 21(7), 1075–1079. doi.org/10.1016/0042-6989(81)90012-2
4. O’Regan, J. K., Deubel, H., Clark, J. J., & Rensink, R. A. (2000). Picture changes during blinks: looking without seeing and seeing without looking. Visual Cognition, 7(1–3), 191–211. doi.org/10.1080/135062800394766
5. Rensink, R. A., O’Regan, J. K., & Clark, J. J. (1997). To see or not to see: the need for attention to perceive changes in scenes. Psychological Science, 8(5), 368–373. doi.org/10.1111/j.1467-9280.1997.tb00427.x
6. Bentivoglio, A. R., Bressman, S. B., Cassetta, E., et al. (1997). Analysis of blink rate patterns in normal subjects. Movement Disorders, 12(6), 1028–1034. doi.org/10.1002/mds.870120629
7. Yang, B., Intoy, J., & Rucci, M. (2024). Eye blinks as a visual processing stage. PNAS, 121(15), e2310291121. doi.org/10.1073/pnas.2310291121
8. Volkmann, F. C., Riggs, L. A., & Moore, R. K. (1980). Eyeblinks and visual suppression. Science, 207(4433), 900–902. doi.org/10.1126/science.7355270
9. Bristow, D., Haynes, J.-D., Sylvester, R., Frith, C. D., & Rees, G. (2005). Blinking suppresses the neural response to unchanging retinal stimulation. Current Biology, 15(14), 1296–1300. doi.org/10.1016/j.cub.2005.06.025

The eye model: MediaPipe Tasks Vision 1.2.0, © Google, Apache License 2.0.