A Delay from Reality


Yesterday, I posted a paper discussing a potential flaw in our perception of reality. Here, I review an article from Scientific American Mind, suggesting how such "flaws" occur from a neurological standpoint.

A Delay from Reality

By Karmen Lee Franklin

i-8529db3c9e238ae8641ac0e2a14b7ced-crash.jpgImagine being witness to a spectacular car accident. The scene seems to happen in slow motion; you notice every detail as it unfolds, such as the sound of crunching metal or scattering shards of glass twinkling in the sun. Later, you realize how late the accident has caused you to be, and notice time passing quickly as you race to your appointment. Did time slow down during the accident, only to speed up after the fact? Or did the difference appear due to a perceptual lag in the brain, triggered by images too horrifying to quickly fade? Cristof Koch, of the California Institute of Technology, attempted to explain this apparent delay of processing reality within the brain by studying the EEG patterns of individuals.

He outlined this experiment in his article, "The Movie in Your Head." Pictures were flashed on a screen for brief intervals while subjects were monitored through electrodes placed on the skull. As they watched, the subjects were asked to decide if a certain image contained an animal or not. The resulting EEG patterns were then compared; after 150 milliseconds, the patterns were nearly identical, indicating the information had been processed in that time. "In other words," he wrote, "after about one tenth of a second something in the cerebral cortex began to distinguish animal from nonanimal pictures" (61.) (This may seem like a short time, but it only takes a few milliseconds for a computer in Hawaii to retrieve data from Seattle, for a dying star to pulse, or for trades on Wall Street to be lost.* In today's high-tech world, is a tenth of a second fast enough?)

In addition to a notable delay in processing, researchers have found that rapid successions of images can result in distorted perceptions from the mind. In one experiment, two different colors of light were flashed in front of a subject for 10 milliseconds each. Rather than seeing two distinct colors, however, the subjects saw a single flash of a third color. Another experiment showed that words seen for only 30 milliseconds were noticeable unless surrounded by unrelated images. For example, individuals could read the word "lion" by itself, but not when the word was sandwiched between random pictures. Researchers called this effect masking, as one image masks another (possibly more actual) image. These and other experiments suggested that reality is digested by the mind in discreet packets. Yet, experiences seem to be solid and continuous.

Koch believed these individual perceived moments, which he called neural correlates of consciousness or NCCs, are strung together within the mind like the frames in a movie, providing a seamless illusion of experience. "Our perception seems to be the result of a sequence of individual snapshots, a sequence of moments, like individual, discrete movie frames, that, when scrolling quickly past us, we experience as continuous motion," he wrote. As in the example of the car accident, if these frames increased in duration, an event would appear to happen faster than usual, as if time had sped up. Conversely, the shorter the duration of the frame, the slower time appears to pass (63.)

Did Koch's research actually shed new light on the issue of perception? In his article, he described the flaws of previous experiments measuring reaction times. When subjects were required to press a button in order to indicate they had seen an image, researchers had to include the motor response time, or the time it took for a subject to press the button. Koch saw the EEG as an improvement on this, as the signals can be observed through changes in electrical activity. However, some results varied. "Depending on the study, the duration of [perceived] snapshots is between 20 and 200 milliseconds. We do not know yet whether this discrepancy reflects the crudeness of our instruments or some fundamental quality of the neurons," he explained (63.) It is easy to speculate that this is the cause of perceived distortions of time; but since what little evidence available is possibly flawed, any concrete understanding remains elusive.

New questions and improved equipment will be necessary to understand the relationship between sense and experience. For instance, in his experiment, Koch only studied the reaction times of the brain to visual stimuli. Most experiences, on the other hand, are composed of multiple sensory inputs. Would sensations of taste, scent, sound, and touch register more or less quickly within the mind, or endure longer, altering the continuity of an experience? It is even possible that some other "senses," such as memory association, reasoning, and imagination, could affect a single experience? Koch suggested that NCCs may be the result of multiple changes in the brain, which cannot be interpreted with EEGs alone. If this is the case, he writes "our state-of-the-art research techniques are inadequate to follow this process.... We need fine grained instruments that cover all of the brain to get a picture of how widely scattered groups of thousands of neurons work together" (63.)

In his attempts to understand perception, Koch showed there is a possible delay of up to 150 milliseconds during the processing of visual sensory information by the brain. This suggests there is a distinct difference between perception and reality. However, for now, as Koch suggested, understanding this difference is "only a dream" (63.) We are just now developing the crude tools we require for understanding the relationship between the brain, perception, and reality itself. Soon, we may be able to time other sensory reactions in the brain.

Koch and his contemporaries explained the sensation of time passing quickly or slowly; perhaps next they should study the reactions of the human mind to scent. For instance, why do we occasionally seem to experience a memory before the presence of a familiar scent registers in our mind? Perhaps a memory is triggered during a delay, similar to that between a visual stimulus and reaction, before a scent is recognized in the brain. Answers to this question and others may eventually surface, as equipment evolves in sophistication and we discover new methods. For all we know, time until then just might seem to pass at light speed.

Notes and Sources: *NASDAQ computers process information more quickly than brokerage firms can swallow. "NASDAQ has been offering this service for about a year and currently has 10 clients on board, says the exchange’s chief information officer, Steve Randich. 'By colocating, these firms are putting algorithms in the location that's going to get transaction turnaround in just a couple of milliseconds, as opposed to what could be 20 to 30 milliseconds for the data to travel across the country,' he says. 'Twenty milliseconds make a difference in terms of what price you get per order.'" -Pallay, Jessica "Milliseconds Matter." Wall Street & Technology: August 22, 2005. Koch, Christof. "The Movie in Your Head." Scientific American Mind. Vol. 16, No. 3. 58-63. 2005.


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Having never witnessed a spectacular car accident, I can't comment on that particular situation. However, I was a participant in a recent experiment in which the subjects were shown an elaborate recorded scenario, in which after about an hour and 45 minutes of setup a beloved character was killed suddenly and in the middle of making a joke. This experiment may not have been ethical, since none of the participants had agreed in advance to it, and indeed the experimenter seems to have thought of the whole thing as a "Big Damn Movie". [BELATED SPOILER ALERT]

Nevertheless, I do remember thinking it odd that the killed character's spouse immediately left the vicinity and went on with the action. Odd especially in view of the known wordiness of the "experimenter", who I will refer to hereafter as Joss. Here we find the advantage of a recorded situation, in that I of course saw the movie more than one time, and in so doing realized that the character's spouse did NOT in fact leave the area immediately, but spent maybe 20-30 seconds reacting. That time was completely gone from my memory of the scene.

Unfortunately none of we subjects were instrumented for EEG's. I'd be curious to see the results if we had been. Judging from the reaction of fans on various message boards, it was a strongly emotional moment for most.

Um, so what's my point? Good question. Probably just that it is possible to evoke strong emotions in a controlled situation, given enough time (and talent) (and money). I'm willing to bet that the emotional response in this case very closely matches what would happen in real life.

By Johnny Vector (not verified) on 07 Feb 2007 #permalink

As it so happens I had an accident this past week, not spectacular though, as I lost control in bad weather and whacked a guardrail (thankfully no one else was involved). Still, my memory of the event is quite vivid and I can remember most of it moment by moment, even though it all happened in less than 10 seconds from when I starting losing control until I came to a complete stop. Just like in the example above, I do remember that at the time it seemed to happen in slow motion. I can even recall thinking different thoughts as the incident progressed ("I can recover", "Maybe I'll just scrape the guardrail", "Oh crap this is gonna be bad"). I'm aware that these thoughts could be false memories that I associated with the accident after the fact, but I'm pretty sure some, if not all, of those thoughts flashed through my mind as my car was spinning. And I'm not the only one. The next day I was reading about a large pile-up in my area caused by the same storm, and one of the drivers involved was quoted as saying he also saw everything happen in slow motion.