Our Brain Tricks Us: A Simple Experiment in Consciousness
If I do my job right, this article will make you question your conscious experience.
Please try this simple experiment*:
- Touch the tip of your nose with your index finger
- As you make contact, note when you feel the sensation on both nose and fingertip (Simultaneous? One before the other?)
- Repeat until you have an answer
A small subset of readers – perhaps drawing worried looks at the local Starbucks - may still be jabbing their snouts. But most of you were probably satisfied after three or four touches.
The sensations seem, of course, to be about simultaneous**.
But things are not always as they seem. Here’s the truth: The two nerve signals from nose and fingertip did not reach your brain at the same time.
It takes longer – significantly longer - for a nerve impulse to travel from finger to brain than from nose to brain. The nose impulse, having less distance to travel, arrives before the fingertip impulse. The difference should be noticeable.
Why do they feel simultaneous then? Quite simply - our brain tricks us.
In the early 80s, Benjamin Libet proved that conscious experience lags behind actual brain activity. The delay is around half a second, and our brain uses this time to construct a smooth simulation of reality. We call this simulation consciousness.
“The content of our consciousness is already processed and reduced, put into context before we experience it,” writes Danish author Tor Nørretranders. “We experience not the raw sensory data but a simulation of them.”
Given the sheer volume of data our senses receive, it makes sense that we pare it down to a manageable format. Consciousness takes time to construct. As a matter of experience, however, we are ignorant of this lag. It seems like we’re humming right along in the present.
But the nose test says otherwise. If events were experienced in real-time, we would feel a touch on the nose a few tics before on the fingertip. Instead – thanks to the half second delay - our soggy supercomputer fools us into thinking the sensations are simultaneous. It’s an incredible illusion.
We experience the world of a half second ago. Yet our brain, through elaborate sleight of hand, doesn’t clue us in. Consciousness is not a real-time event, but a post hoc simulation.
Sometimes, when I want to stop taking life so seriously, I touch my nose... and recall the mystery of being human.
*Credit to Sam Harris
**If you felt nose first, it's likely because it's more sensitive to the touch.
Nørretranders, Tor. The User Illusion: Cutting Consciousness down to Size. New York: Viking, 1998. Print.