Neuroscientist sees
how vision runs ‘under the hood’
By Brian Mezerski
Humans open
their eyes and see the world. Vision may
seem entirely uncomplicated, but there is something much deeper happening to
understand this “genuine phenomenon,” according to one neuroscientist.
David
Eagleman, who works at the Baylor College of Medicine, said in a lecture to
students at Elon University Monday night that most of what humans see, think
and believe is created deep within the unconscious brain. People are unaware that the process that makes
vision seem easy is happening, according to Eagleman.
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Neuroscientist David
Eagleman answers a question
about whether different humans see the same thing.
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“The only
reason vision seems effortless to us is because of the massive amounts of
machinery that you have running under the hood,” Eagleman said.
Vision is
not like a camera that simply takes a picture.
Eagleman said vision is all about the internal activity in the brain,
the organ located under the human “hood,” or skull.
The brain
is a key component in human vision.
One-third of it is devoted to vision, Eagleman said. But he found, through his studies of human
color interpretations, that the brain may read an image that does not match up
to actual reality.
“It makes a
whole bunch of assumptions about what’s happening,” Eagleman said, “and it
serves up to you a story about what color it thinks things are.”
Eagleman
said there is a phenomenon that causes different people to see these different
realities. Synesthesia is the condition
in which a person’s sensory inputs are blended together, according to Eagleman. Humans with the most common form of
synesthesia see numbers, letters, days and months that trigger a color
experience.
“This is
automatic and involuntary and unconscious,” Eagleman said. “It’s not a hallucination. Internally, there’s this experience of different
colors that is self-evidently equivalent.”
It may be
difficult to distinguish those with synesthesia, a condition that affects about
4 percent of the population. So Eagleman
built an online consistency test that successfully determines who is a true
synesthete.
“We’ve been
able to really revolutionize what’s been happening with understanding the
behavior of synesthesia,” Eagleman said.
Eagleman
said he discovered more than 20,000 rigorously verified synesthetes through the
online test.
Participants were shown a text
character and then picked the best color that matches the letter or number
based on their personality. Participants
later were returned to the letter again and were asked to choose a color. Synesthetes are able to replicate their first
choice, choosing the nearly identical color that they originally associated with
the letter.
The study showed how vision has
transitioned into a neurological analysis.
“This used to be in the realm of
philosophical speculation,” Eagleman said.
“Now of days, we’ve been able to elevate this to a real scientific
problem.”
The synesthesia study serves as an
example of how the complexities of understanding vision can extend to the
entire world.
“Any form of cross-sensory blending
that you can imagine,” Eagleman said, “we have found somewhere, whether vision,
hearing, taste, touch, temperature or personality.”
