Nautilus Members enjoy an ad-free experience. or Join now .

Nothing focuses the mind like a moment of peril. John Hockenberry, the heavily-decorated journalist and commentator, had one of those nearly four decades ago. Yet it has never left him, and it always plays out in his memory, as he puts it, “in super slo-mo.”

“About 38 years ago, I was on a road in Pennsylvania. I was sleeping in the back of a car. I woke up. The driver of the car was also asleep,” Hockenberry recounted from his wheelchair in early June at this year’s World Science Festival in New York as he opened up a panel discussion on time perception.“ The car was veering off the road. The passenger next to her reached over very slowly, it seemed, grabbed the wheel, and pulled that wheel as hard as she could … and the car veers to the right. And very slowly we hit the guardrail, the car flips into the air, and I can feel in my gut that all of life is going to change.”

Nautilus Members enjoy an ad-free experience. Log in or Join now .

Retired fire chief Richard Gasaway refers to this apparent slowing down of time in tense situations as tachypsychia, which roughly translates as “fast mind.” “This phenomenon afflicts many first responders,” Gasaway claims, based on hundreds of interviews he has conducted for his research, blog, and speaking engagements on “situational awareness.” Bolstered also by what he judges to be personal experiences of tachypsychia, Gasaway has come to consider it as a sometime component of the overall stress response. For first responders, the phenomenon is dangerous, he says, because it can warp situational awareness and decision-making processes.

But is tachypsychia real, or an illusion? David Eagleman of the Baylor College of Medicine set out to answer this question with a test. Together with his colleagues, he developed a wristwatch-like “perceptual chronometer” that alternately displays red digits and their negative images (a red background with unlit pixels in the shape of the digits) at rates faster than a threshold at which the toggling images fuse into what appears to be a uniform patch. This threshold is called a critical fusion frequency, or CFF. Eagleman hypothesized that if he could terrify people while they were looking at the chronometer, then their CFF would spike, they would switch into slow-motion perception mode, and they would suddenly be able to discern the digits on the chronometer.

Nautilus Members enjoy an ad-free experience. Log in or Join now .

The frequent report by schizophrenics of hearing voices might amount to a rational interpretation of their subjective, temporally-dysfunctional experience.

To carry out the tests, Eagleman took 20 people to the Zero Gravity Thrill Amusement Park in Dallas. There he strapped them into the Suspended Catch Air Device of the 16-story-high “Nothin’ but Net” ride, in which the chronometer-wearing participants would free fall 31 meters before landing in a net. The participants were tasked to keep an eye on their chronometer during their jaw-clenching, 2.5 second drop. One participant squeezed her eyes shut the entire time and so she yielded no data. 

The data from the other participants made it clear: No one could discern the digits during their free falls. But, when asked after the fact to estimate the duration of their own falls (by replaying their experience in their minds and with a stopwatch in hand), the participants recorded, on average, that their drop lasted about a third longer than the drops of others they had witnessed as at-ease spectators. Eagleman concluded the subjective experience of time slowing down under harrowing circumstances is an artifact of memory, not an actual trait of real-time perception. In short, time was not slowing down for anybody.1

“Under normal circumstances, most of the stuff flowing through your sensorium, you don’t remember,” Eagleman explained. “What happens in a life-threatening situation is that everything gets written down. Everything is retained in memory.” Because the brain is not used to memory of such density, he continued, “the brain’s interpretation is that the whole thing must have gone more slowly.”

Nautilus Members enjoy an ad-free experience. Log in or Join now .

But what if a test subject was affected, not by a moment of peril, but by some mental or cognitive dysfunction? Eagleman and colleagues at Baylor and the Harris County Psychiatric Center in Houston asked people with schizophrenia and those in a control group to report how many stimuli, such as letters, pictures, and faces, they could perceive as they watched a series of rapidly flashing screens. The results suggested, Eagleman says, “a single flash that to you lasts 100 milliseconds, might seem like 120 milliseconds to someone with schizophrenia.” This 20 percent difference at the sensory level, he speculates, could belie temporal dysfunction at higher cognitive levels. For example, it could make it difficult to map the internal dialog one routinely hears in one’s “mind’s ear” onto oneself. In such a situation, Eagleman suggests, the frequent report by schizophrenics of hearing voices might amount to a rational interpretation of their subjective, temporally-dysfunctional experience.2

With evidence in hand of at least a limited spread of CFFs among us, humans join a much broader spectrum ranging across the animal kingdom, according to a cross-species analysis published recently in the journal Animal Behavior. The CFF for people is, on average, 60 flickers per second, which is why televisions’ refresh rates are at or above that frequency. In the animal kingdom, it runs from as low as 6.7 for a cane toad, to 108 for a ground squirrel, to 240 for a common blowfly. Generally speaking, the faster an animal’s metabolism or the smaller its size, the higher its CFF.3

Are swordfish visitors from another temporal dimension?

Nautilus Members enjoy an ad-free experience. Log in or Join now .

These differing CFF values seem to offer some fascinating explanatory power. No wonder it is hard to kill a fly with your murderous swatting hand. With a CFF of 240, the fly might well see your approaching hand as though it were muscling through molasses. And how about those aeronautical stunts by birds flying through thickets of vegetation? With CFFs around 100, they are likely visually sampling their surroundings at super-human rates that allow for faster mid-air adjustments.

There is some evidence that this temporal dimension could be critical to the planet’s ecological competitions: “Time perception might constitute an important and overlooked dimension of niche differentiation,” says zoologist Andrew Jackson of Trinity College Dublin, one of the authors of the Animal Behavior article. When cold-blooded swordfish dive in pursuit of squid, for one, they upshift their CFF by surging warm blood to their eyes. “This presumably gives them a huge advantage when they dive to hunt relatively sluggish squid in the colder waters below,” says Jackson. “In this way, swordfish essentially are visitors from another temporal dimension … The squid probably stand little chance of survival.” People can’t get away with this eye and brain warming tactic to crank their CFF; it would mean heating up tissue into high-fever territory where proteins unravel and cells start to not care about living anymore.

That said, Jackson believes that it may be possible that we all have slightly different CFFs, which could help explain details of our personality, talents, choices, and perceptions. “Should a person have a higher CFF than their group mates, then they would effectively have the potential to react to events in the world that would to their group mates seem impossibly fast,” Jackson said. “I kind of wonder if this might explain the feeling sometimes when you are playing sports like soccer and you feel completely on top of your game, and able to breeze past your opponent with a feeling that the game feels almost slow to you.”

On Jackson’s research to-do list are studies that might characterize natural variations in flicker fusion rates among individuals and how much an individual’s CFF might vary under many different circumstances. “Where it gets really interesting,” Jackson adds, “is whether there are consequences for these differences in our everyday life.”

Nautilus Members enjoy an ad-free experience. Log in or Join now .

Jackson is in the midst of writing up a grant application for work that would dig into these questions. If the money comes through, he says, he would love to recruit fast-action aficionados of Bruce Lee and LeBron James caliber for whom it is conceivable that above-average CFF rates could play into their magnificent physical feats. Regarding possible CFF-cognition connections, Jackson says he would be interested to see whether “low-CFF individuals” might be more apt to miss subtle but important cues in, say, facial expressions. And there is one more thing Jackson would like to explore: whether it might be possible to train people to increase their CFF rate with the intention of improving sporting performance or to help treat temporality-based dysfunctions. 

Researchers warn that the data in hand is too scant to conclude much about CFFs in humans for the time being, or even to say with certainty what the connection is between CFFs and subjective time perception. But the variability of CFFs among animals and those with mental diseases, together with our subjective experience of time, leave us with an interesting question to ponder: Are there people who, like the swordfish, live in another temporal dimension?

Ivan Amato is a science and technology writer in Silver Spring, Maryland. He runs D.C. Science Café.

Nautilus Members enjoy an ad-free experience. Log in or Join now .


1. Stetson, C., Fiesta, M.P., & Eagleman, D.M. Does time really slow down during a frightening event? PLoS One 2, e1295 (2007).

2. Parsons, B.D., et al. Lengthened temporal integration in schizophrenia. Neuropsychologia 51, 372–376 (2013).

Nautilus Members enjoy an ad-free experience. Log in or Join now .

3. Healy, K., McNally, L., Ruxton, G.D., Cooper, N., & Jackson, A.L. Metabolic rate and body size are linked with perception of temporal information. Animal Behaviour 86, 685-696 (2013).

close-icon Enjoy unlimited Nautilus articles, ad-free, for less than $5/month. Join now

! There is not an active subscription associated with that email address.

Join to continue reading.

You’ve read your 2 free articles this month. Access unlimited ad-free stories, including this one, by becoming a Nautilus member.

! There is not an active subscription associated with that email address.

This is your last free article.

Don’t limit your curiosity. Access unlimited ad-free stories like this one, and support independent journalism, by becoming a Nautilus member.