A “time slice” theory of
consciousness suggests we’re not continually aware of our
surroundings
Olivia Goldhill April 18,
2016 QuartZ
How do you perceive your
own consciousness?
If this is the first time
you’ve considered such a question, it’s likely you consider it to
be smooth and continuous, registering movements and changes as
events happen in the world around you. You most likely consider
yourself conscious all the time, unless you’re asleep or knocked
out.
But for those who study
the mind, including philosophers, psychologists and
neuroscientists, this notion of consciousness is far from obvious.
While intuitively, we may believe that consciousness is a continual
flow, there’s considerable evidence to suggest that our conscious
perception comes in discrete snapshots, like distinct images
flicking quickly through a film reel. A paper published in PloS
Biologythis month has put forward a theory in an attempt
to reconcile these theories of consciousness, arguing that
consciousness is in fact developed in two stages.
First, the authors argue,
we unconsciously process visual stimuli continuously, and are
oblivious to this stage. We only then become consciously aware of
the information once it has been transferred to conscious
perception, which happens in discrete moments, or “time
slices.”
Michael Herzog, a
professor at the École polytechnique fédérale de Lausanne’s Brain
Mind Institute in Switzerland, and Frank Scharnowski, a cognitive
neuroscientist at the University of Zurich, argue that we’re
unaware of the gaps in our consciousness. They say there can be a
400-milisecond lag between unconsciously receiving stimuli and
transferring it to conscious perception.
“We perceive time as
continuous just as we perceive a line as continuous even though its
ink is of discrete atomic nature,” the authors write in their
paper.
But our perception of
conscious does not align with reality. “According to our model, the
output of unconscious processing is discrete, meaningful, and
rendered conscious at once. Large parts of unconscious processing
will never reach consciousness,” the researchers say.
The authors note that the
debate over how consciousness works has a long history. In the
third century BC, the Abhidharma Buddhist schoolput forward the
theory that
consciousness is made up of discrete moments. There
are numerous more recent
papers arguing
for just such a conclusion. Meanwhile, experiments show that when two
stimuli are
presented in rapid succession, they’re perceived simultaneously,
while discrete perception is thought to explain various visual
tricks, such as the optical illusion that often makes spoked wheels
look as though they’re moving in
reverse, and flash lag
illusion, where
a flash that occurs in the same place as a moving object is
perceived to be in a different location.
Herzog and Scharnowski
argue that the evidence points to neither clear-cut continual nor
snapshot theories of consciousness, but that their two-stage theory
reconciles our sense of continual consciousness with the
counter-evidence.
Axel Cleeremans from the
Université Libre de Bruxelles, who was not involved in the study,
tells Quartz that others have
come to a similar conclusion.
Ultimately, Herzog and
Scharnowski note in their paper that the debate over
consciousness remains unresolved. Their theory may fit
certain key characteristics of consciousness, but it doesn’t yet
hold definitive answers.