Mind

A Biological Theory of Consciousness May Be Within Reach

New research pinpoints the a-ha moment when information enters the human consciousness.

Jenni Holma/Getty Images

One of the most often-told anecdotes in the history of science relates how the ancient Greek scholar Archemides had a moment of insight while getting into a bathtub.

Archimedes had been asked to figure out whether a king’s crown was made of pure gold. As the water rose around him, he realized he could submerge the crown to reveal out its exact volume in displaced water, and therefore how much the object ought to weigh if it were indeed pure.

According to legend, Archemides exclaimed “eureka,” which means “I’ve got it” in ancient Greek, and went running through the city naked to share the news.

The crown, it turned out, had been mixed with silver.

Now scientists have taken a new approach toward exploring what goes on in the human mind when it experiences in a moment of epiphany. Specifically, the study suggests scientists have found a way to observe in the moment when information bubbles to the level of consciousness.

The results suggest that uncovering the biological foundations of consciousness may well be within the grasp, the researchers say, despite the highly abstract nature of the problem.

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The paper supports an understanding of a process in which the brain collects data and then, at a certain point, decides enough is enough and turns the information into a conscious thought, according to the paper’s senior author Michael Shadlen of Columbia University's Mortimer B. Zuckerman Mind Brain Behavior Institute.

“The way the brain makes decisions is that it assembles evidence, and if it doesn’t have enough evidence, then it gets a little more,” Shadlen said. “And at some point, it stops.”

For the study, which appeared today in the journal Current Biology, participants watched a group of dots sway on a screen as if in a breeze.

They had to decide whether the dots were moving generally to the right or to the left, and then, later, specify the exact moment in time at which they arrived at their decision.

What remained unknown was whether the subjects were correct about when they arrived at their conclusion.

Had the unconscious brain somehow put the pieces together earlier, or did it develop a conclusion later and left the conscious mind with a mistaken impression about when it happened?

Shadlen and his colleagues deployed a neuroscientific and mathematical model to predict how accurate decisions should be if made within a certain timeframe, based on previous studies about decision-making at the level of individual brain cells.

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The degree of accuracy reported by the real participants lined up well with what their model predicted, lending credence to the idea that, yes, they in fact had their “eureka moment” at the time they later thought they did.

One implication of the results is that higher-order cognitive functioning may at times be explained using simpler neural operations that are better understood, Shadlen said.

“My whole research program is all about how you can use relatively simple operations to understand the deeper, cognitive, thoughtful things our brains achieve,” Shadlen said. “Here’s an example of an event that’s purely subjective, but involves becoming aware, or conscious, that was explained by a relatively well-understood neural mechanism.”

The study raises the possibility that a deep understanding the human brain's most complex thoughts and feelings, once the purview of philosophy, may come to be understood biologically.

“Embedded in this larger view is the implication that this big mystery that we call consciousness, philosopher’s consciousness, is within the crosshairs of neuroscience, without magic,” Shadlen said. “That’s the big picture.”