   Neuroscience tells us that most of the work done by our brains happens on
   an unconscious level, but when does that "a-ha!" moment occur? And what
   happens during it? New research investigates.

   hand holding brain lightbulb
   A new study investigates when the 'a-ha!' moment takes place in the brain,
   and how similar it is to other brain processes.

   Many of us have noticed that we seem to get our best ideas when we're in
   the shower, or that we can find the answer to a difficult question when we
   least think about it.

   A large body of neuroscientific studies has pointed out that the brain
   does a lot of work in its spare time, the so-called idle state - wherein
   the brain does not appear to be thinking about anything at all - and that
   this is the time when it works at its hardest to find solutions to complex
   problems.

   With time and advances in neuroscience, it has become more and more clear
   to researchers that Freud was right and the mind, as well as the brain, do
   work unconsciously. In fact, it would be safe to say that what is
   consciously known to us is just the tip of a much larger iceberg, deeply
   submerged in unconscious waters.

   But the exact moment at which information becomes known to us - or when
   the "tip of the iceberg" pierces through the water, and the unconscious
   becomes conscious - has been somewhat of a mystery, from a neuroscientific
   point of view.

   In other words, we do not yet know when that intellectually satisfying
   "a-ha!" moment takes place, or what the biology is behind it. This is why
   a team of researchers at Columbia University in New York City, NY, set out
   to investigate this moment in more detail.

   The scientists were led by Michael Shadlen, Ph.D., of Columbia
   University's Mortimer B. Zuckerman Mind Brain Behavior Institute, and the
   findings were published in the journal Current Biology.

The hypothesis

   Dr. Shadlen and colleagues started out from an interesting hypothesis, one
   which they derived from previous research on the neurobiological processes
   involved in decision-making.

   As the authors explain, research conducted in both monkeys and humans
   shows that many of our decisions take place at a point when the brain
   "feels" as though it has gathered enough information, or when a critical
   level of information has been accumulated.

   This process of making a decision once the brain has accumulated enough
   evidence bears the name of "bounded evidence accumulation." Reaching this
   threshold is important because, although the brain does not use all of the
   information available, it uses as much as is necessary to make a speedy
   yet accurate decision.

   The researchers wondered whether or not this threshold is also responsible
   for our "eureka!" moments.

   In Dr. Shadlen's words, "Could the moment when the brain believes it has
   accumulated enough evidence be tied to the person's awareness of having
   decided - that important 'a-ha!' moment?"

Examining the 'a-ha!' moment

   To answer this question, the scientists asked five people to perform a
   "direction discrimination" task. In it, the participants looked at dots on
   a computer screen. The dots moved randomly, as grains of sand would when
   blown by the wind. The participants were asked to say in which direction
   the dots had moved.

   The moment they "decided" which direction the dots seemed to be taking was
   considered to be the equivalent of the "a-ha!" moment.

   In the center of the screen, there was a fixed point and a clock. The
   display also had two "choice targets" - namely, left or right - and these
   were the directions in which the participants had to decide that the dots
   had moved.

   Shortly after the dots had stopped moving, the participants used an
   electronic, hand-held stylus to move the cursor in the direction that they
   thought the dots had moved.

   To determine when the decision was made, the researchers used the
   technique called "mental chronometry" - that is, after they made their
   decision, the participants were asked to move the clock backward to the
   point when they felt that they had consciously done so.

   "The moment in time indicated by the participants - this mental
   chronometry - was entirely subjective; it relied solely on their own
   estimation of how long it took them to make that decision," Dr. Shadlen
   says. "And because it was purely subjective, in principle it ought to be
   unverifiable."

'A-ha' moment similar to making a decision

   However, by applying a mathematical model, the scientists were able to
   match these subjective decision times to the bounded evidence accumulation
   process.

   The subjective decision times fit so well with what the scientists
   determined as the evidence accumulation threshold that they were able to
   predict the choices of four of the five participants.

   "If the time reported to us by the participants was valid, we reasoned
   that it might be possible to predict the accuracy of the decision,"
   explains Dr. Shadlen.

   "We incorporated a kind of mathematical trick, based on earlier studies,
   which showed that the speed and accuracy of decisions were tied together
   by the same brain function." This "mathematical trick" was the evidence
   accumulation model.

     "Essentially, the act of becoming consciously aware of a decision
     conforms to the same process that the brain goes through to complete a
     decision, even a simple one - such as whether to turn left or right."

     Michael Shadlen, Ph.D.

   In other words, the study shows that the conscious awareness of the
   "a-ha!" moment takes place precisely when the brain has reached that
   threshold of evidence accumulation.

   The findings provide unique insights into the biology of consciousness,
   say the researchers, and they bring us closer to understanding the
   biological basis of decisions, ethics, and, generally, the human mind.
