We may not be nearly as aware of the world around us as we'd like to think, according to a thought-provoking new theory in cognitive neuroscience.
Just like a movie appears continuous even though it's made up of a series of separate images, our brains might use a two-stage model of visual processing to perceive the world in short blips, or "time slices." The brain may then piece the individual frames together into an unbroken image of the world, the new "time slice theory" suggests.
"We intuitively believe that we are directly aware of things at any moment in time," Dr. Frank Scharnowski, a cognitive neuroscientist at the University of Zurich and one of the study's authors, told The Huffington Post on Friday. "This is not the case."
In a paper published Tuesday in the journal PLoS Biology, an international team of researchers suggests that there's some lag time between when we actually see something and when we become aware of it.
Data from previously published psychological and behavioral experiments supports this theory, the researchers determined. The two-stage model they devised suggests that our brains first process visual information from the environment while we're in an unconscious state, and then transfer it to our conscious awareness.
Here's what the researchers believe happens: First, we rapidly and unconsciously process visual information, which takes only several milliseconds. Then, the features of that visual information are integrated into our conscious awareness in a coherent way, which takes several hundred milliseconds.
This would mean that consciousness comes in a series of 400-millisecond "time slices," with gaps of unconsciousness in between. Got that?
"We do not experience stimuli and objects during their actual presentation, but much later when they are rendered conscious," Scharnowski said. "Such a representation is akin to the answer to the question of how were your holidays: 'We enjoyed the colors of the Tuscan landscape for three days, and then went to Venice for four sunny days at the sea.' The response is a compressed post-hoc description regarding the temporal features of the trip even though the actual event was spread over a long period of time."
So how much faster is human vision than perception? Much faster.
"We can see the time difference when two bars are presented with a delay of 3 milliseconds," Scharnowski said. "In contrast, conscious perception is much slower and can be delayed for several hundred milliseconds."
This time lag is a good thing for perception, according to study co-author Dr. Michael Herzog, a professor at the École polytechnique fédérale de Lausanne's Brain Mind Institute in Switzerland.
"The brain wants to give you the best, clearest information it can, and this demands a substantial amount of time," he said in a statement. "There is no advantage in making you aware of its unconscious processing, because that would be immensely confusing.”
If we don't see the world as a continuous flow and instead process it more like a string of snapshots, human consciousness may not be as coherent as we'd like to think.
"Although this is counterintuitive, it is nothing scary," Scharnowski said. "We also perceive the letters of this text as continuous even though they are of discrete pixels."
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