- The act of blinking appears to trigger a suppression of neuronal activity in the visual brain.
- A recent study suggests that our perception of the flow of time itself is suppressed during blinks.
- The neuronal changes triggered by blinking might just be a way to escape the pressures of the world, however briefly.
We blink naturally every few seconds, and we can choose to blink anytime. Wouldn't it be great if you could blink away your troubles magically, like the title character from the 1960s sitcom "I Dream of Jeannie" famously did?
I’ve written previously about how blinks partially give away your cognitive state, and, in particular, you blink more when conversing than when reading (which is one way to tell if someone is paying attention to a conversation on Zoom).
But there is another side to blinks that reveals deep connections to processes going on in your brain that make sense of the world. The neuronal changes triggered by blinking might just be a way to escape the pressures of the world, however briefly.
To understand why blinks are interesting, we need to know what happens to our perception of the world when we blink. The answer seems obvious: We can't see anything. But reality is more complex—and fascinating.
What You See When You Blink
The seminal study on what we perceive when we blink was carried out by psychologist Frances Volkmann and colleagues in 1980 in a paper that has become legendary in vision science, but is little known outside the field.
The question is this: Does blinking simply block out the world for an instant, or does it have more systemic effects in relation to our brain's construction of consciousness? The researchers investigated this by asking a more specific question: If you could somehow deliver light to the retina at the back of the eye while the eyes are closed, what would you see?
Making this happen seems impossible, but Volkmann and her colleagues came up with an ingenious solution. It was known that the orbits that house the eyes are not completely light-proof. Could a harmless blast of visible light delivered inside the head do the trick? The researchers found that it could: People could readily see light delivered to their eyes by way of the inside of the mouth.
The researchers fitted a fiber-optic bundle into the roof of participants' mouths and covered their eyes with blacked-out goggles. When the light fibers were illuminated, participants could see light that penetrated the intervening tissue and bone to stimulate the lower part of the retina. Because we perceive the retinal image as upside down, the participants saw this cloudy glow in their upper visual field, even though their lower retina was being stimulated.
The task in the experiment was to detect when the mouth lights were briefly dimmed. The researchers compared detection ability both when participants were instructed to voluntarily blink and without blinking. They found that the ability to detect the dimming fell off dramatically during blinks, even though there was no way that the blink could block the light. This means that the act of blinking must trigger some kind of interruption in the workings of the visual brain. If you could blink without closing your eyes, your visual world would still be dimmed, if not abolished, for a few hundredths of a second.
In some ways, this makes sense. Why waste conscious experience—and the brain power it consumes—on seeing the back of your eyelids, which happens all the time, and provides no new visual information? Skipping over awareness of the momentary dark could make it easier for the brain to connect visual information across the gap in sight. A similar suppression happens when we dart our eyes from place to place: You have no conscious awareness of the split second during which the eyes are in motion (though blinks take considerably longer).
Blinks and Consciousness
Volkmann’s study has inspired hundreds of subsequent studies. There is now evidence from recordings inside the brains of cats and monkeys that the cause of the visual interruption is blink-dependent suppression of neuronal activity in the occipital cortex, at the rear of the brain. Through mechanisms that have not been elucidated yet, the act of blinking seems to cause cells in the visual brain to fire less often during the blink.
In a 2019 paper, Shany Grossman and colleagues took the visual suppression idea a step further. If blinks really interrupt time as far as consciousness is concerned, do our perceptions of the outside world really contract in time? Or, as Grossman and colleagues put it, “Where does time go when you blink?”
Grossman and colleagues had participants estimate the length of time during which a white circle was presented on a dark screen. The actual time interval during which the circle was shown ranged from about half a second to almost three seconds. Grossman and colleagues used an eye tracker to detect blinks during the estimation task. Using somewhat complicated but sensible statistical analyses, they found that people estimated the time interval as significantly shorter if they blinked while seeing it, compared to trials when there was no blink. This suggests our perception of the flow of time itself is suppressed during blinks.
Blink to Escape It All?
If blinks offer us a brief pause from reality, could they be beneficial to mental health in daily life? There is no direct evidence that this is the case, but I think blinking more might be beneficial. It certainly can't hurt, and it requires a truly minimal investment of time.
Nevertheless, some caveats are warranted. Any direct effect of blinks on your mind will be brief. Also, based on data from Grossman and colleagues, auditory time does not appear to slow down during blinks. Participants judged the length of audio stimuli as just as long when blinks occurred as when they didn't.
It is also not clear what, if any, differences exist between the effects on the brain of spontaneous versus voluntary blinks. Existing research largely treats these two situations as equivalent. But since you can close your eyes voluntarily for long periods, any neuronal slowdown caused by closing your eyes should not be ongoing; otherwise, normal vision might be compromised when your eyes re-open (especially if you have moved). More research is needed.
If there is a lesson from this area of research, it is that blinking is more significant for our brains than we realize. And blinking more might just be good for us, especially if we have been having a cognitively demanding day and want to escape for a moment. Just don't expect magic.
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Grossman, S., Gueta, C., Pesin, S., Malach, R., & Landau, A. N. (2019). Where does time go when you blink? Psychological Science, 30(6), 907-916.
Volkmann, F. C., Riggs, L. A., & Moore, R. K. (1980). Eyeblinks and visual suppression. Science, 207(4433), 900-902.