I like to book surf. If something I am enjoying references another intriguing book, I try to hunt it down. And if that second book mentions a third tempting tome, I go after that too, following the thread as far as it will take me. In his book The Shallows, Nicholas Carr cites some research described in What’s Next? Dispatches on the Future of Science, a collection of 18 short and eminently readable essays by scientists working at the cutting edge of their respective fields.
In a piece called “Brain Time”, David M. Eagleman recounts his investigations into how the brain reconciles multifarious streams of incoming data into a coherent perception of “now”: a feat much harder than it seems. Unlike fiber optics, neurons don’t communicate at anything near light-speed. Indeed, the signal from a pin prick to your toe takes considerably longer to reach your brain than one given simultaneously to your nose. So how does the brain register them as concurrent? Or as Eagleman asks:
Why didn’t you feel the nose-touch when it first arrived? Did your brain wait to see what else might be coming up the pipeline of the spinal cord until it was sure it had waited long enough for the lower signal from the toe? Strange as that sounds, it may be correct. It may be that that unified polysensory perception of the world has to wait for the slowest overall information. Given conduction times along limbs, this leads to the bizarre but testable suggestion that tall people may live further in the past than short people.
Also, different senses communicate to our brains at different speeds, which, if you think about it, isn’t exactly news. It’s why we start foot-races with gunshots and not light-flashes.
So how does the brain resolve all these variously arriving inputs into a unity? Well, the answer Eagleman postulates is as fascinating as it is simple. We understand the world by involving ourselves in it:
It has been shown that the brain constantly recalibrates its expectations about arrival times. And it does so by starting with a single, simple assumption: if it sends out a motor act (such a as a clap of hands), all the feedback should be assumed to be simultaneous and any delays should be adjusted until simultaneity is perceived. In other words, the best way to predict the expected relative timing of incoming signals is to interact with the world: each time you kick or touch or knock on something, your brain makes the assumption that the sound, sight and touch are simultaneous.
Eagelman is keen to emphasize that the perception he is investigating here is conscious awareness. Humans, like all higher animals, are completely capable of making “pre-conscious” decisions with their spinal cords, which is how you can remove your hand from the hot stove before the pain even registers. This difference between pre-conscious perception and consciousness itself leads Eagleman to stare down the ultimate question: what do we need the latter for anyway?
What is the use of perception, especially since it lags behind reality, is retrospectively attributed, and is generally outstripped by automatic (unconscious) systems? The most likely answer is that perceptions are representations of information that the cognitive systems can work with later. Thus it is important for the brain to take sufficient time to settle on its best interpretation of what just happened rather than stick with its initial, rapid interpretation. Its carefully refined picture of what just happened is all it will have to work with later, so it had better invest the time.
Humans don’t have sharp claws, or big teeth, or wings or echo-location. We have something ultimately much more powerful: clear, cogent, handily referable memories. We experience time as a stream because that’s the best, and perhaps only way to accurately record experience with the level of retrievable complexity that we require to be, well, human. In fact, Eagleman concludes by casting doubt on the notion of time as a scientifically sound first principle.
Most of our current theoretical frameworks include the variable t in a Newtonian, river-flowing sense. But as we begin to understand time as a construction of the brain, as subject to illusion as the sense of color is, we may eventually be able to remove our perceptual biases from the equation. Our physical theories are mostly built on top of our filters for perceiving the world, and time may be the most stubborn filter of all to budge out of the way.
With this line of thought, Eagleman follows down a trail blazed by Henri Bergson and Kurt Gödel, whose evocative investigations of time have been all too often ignored or poorly understood by serious scientists and philosophers over the last century.
Implications for Theatre:
What’s more, Eagleman may have unwittingly stumbled on an answer to the most persistently nagging question of my chosen art form: why is live theatre so much more excruciating than movies or TV when it’s bad, and so much more powerfully transcendent on those much rarer occasions when it is good? Well maybe it is because film and TV do most of your brain’s work for you, pre-packaging all the various elements of sight and sound into a perfectly corroborated unified mega-signal. In the theatre, the data hits our brains like it does in real life—like it did on the savannah a million years ago— as an unreconciled rough draft. Our brains are working harder in the theatre to piece it all together. Film and television tell our brains stories; theatre makes our brains do the telling. (For my own theatrical explorations of time’s mutability, check out my play The Ten Thousand Things.)
David M. Eagleman’s bio says that in addition to serving as the director of Baylor College of Medicine’s Laboratory for Perception and Action, he is also the author of a book of fiction called Sum: Forty Tales from the Afterlives. Cowabunga baby! Surf’s up!
