This is a basic introduction to human visual perception and how the brain processes information obtained by the eye.

1. Week 2
Visual Perception
A R T 1 0 0
U n d e r s t a n d i n g V i s u a l C u l t u r e

2. agenda 9.2.14
questions?
artworlds: brief review
function of the eye
how eye and brain work together to create vision
the active, constructed nature of vision

3. What is “art-like” about the
Mona Lisa?
it is an oil painting,
it is painted by one of the most famous artists in history,
and it is located in the Louvre, one of the most well-known
art museums in the world.

4. LEONARDO DA VINCI
Portrait of Lisa Gherardini, wife of
Francesco del Giocondo, known as the
Mona Lisa (the Joconde in French)
c. 1503–06
oil on panel
30.3 x 20.8 inches
Acquired by François I in 1518

5. “Leonardo undertook to execute, for Francesco del Giocondo, the portrait
of Mona Lisa, his wife, and after he had lingered over it for four years, he
left it unfinished; and the work is today in the possession of King Francis of
France, at Fontainebleau. Anyone wishing to see the degree to which art
could imitate nature could readily perceive this from the head; since therein
are counterfeited all those minutenesses that with subtlety are able to be
painted: seeing that the eyes had that lustre and moistness which are
always seen in the living creature, and around them were the lashes and
all those rosy and pearly tints that demand the greatest delicacy of
execution. The eyebrows, through his having shown the manner in which
the hairs spring from the flesh, here more close and here more scanty, and
curve according to the pores of the flesh, could not be more natural. The
nose, with its beautiful nostrils, rosy and tender, appeared to be alive. The
mouth with its opening , and with its ends united by the red of the lips to
the flesh-tints of the face, seemed, in truth, to be not colours but flesh. In
the pit of the throat, if one gazed upon it intently, could be seen the beating
of the pulse: and indeed it may be said that it was painted in such a
manner as to make every brave artificer, be he who he may, tremble and
lose courage. He employed also this device: Mona Lisa being very
beautiful, while he was painting her portrait, he retained those who played
or sang, and continually jested, who would make her to remain merry, in
order to take away that melancholy which painters are often wont to give to
their portraits. And in this work of Leonardo there was a smile so pleasing ,
that it was a thing more divine than human to behold, and it was held to be
something marvelous, in that it was not other than alive.”
Giorgio Vasari ‘The Lives of the Most Excellent
Painters, Sculptors, and Architects’ 1550

8. http://www.nytimes.com/int
eractive/2012/04/14/world/e
urope/Not-Just-Another-
Fake-Mona-
Lisa.html?ref=europe&_r=0

9. Marcel DUCHAMP
L.H.O.O.Q
1919
postcard with doodle

10. Andy WARHOL, Double Mona Lisa, 1963
Silkscreen ink on linen
28-1/8 x 37-1/8 inches

11. Andy WARHOL
Mona Lisa
1963
Acrylic and silkscreen on canvas
44 x 29 inches

12. Andy WARHOL
Thirty Are Better Than One
1963
Synthetic polymer paint and
silkscreen ink on canvas
110 x 94 inches

13. Vik MUNIZ, Double Mona Lisa, After Warhol, (Peanut Butter + Jelly) 1999,cibachrome

14. Briefly, we will
study the eye and the dynamic process of visual
perception, to understand how our brains create
the images we see.

15. But in general in this course, we are interested not
in the “nature” of vision, but in its culture; in
other words, how humans have developed
languages of visual communication given our
status as sighted creatures.

16. http://www.aoa.org/patients-and-public/resources-for-teachers/
how-your-eyes-work?sso=y

17. Most people assume that vision works as pictured in the diagram below.
Put in words: our vision is just what our eye sees and reports to the brain.
schematic diagram of how vision works
(please note: this diagram is WRONG)

18. “the eye is like a camera”
This analogy holds up to a point.
The point at which it no longer holds
is the retina.
Please note: this diagram is TRUE up to a
point and then becomes FALSE.

19. Please note: this diagram is still a bit misleading, but it’s a whole lot better than the
previous one.

20. why is the eye/camera
idea wrong?
FIRST REASON. There is no “image,” no picture in the eye
at all. All that happens in the eye is that light admitted
through the pupil and focused through the lens differentially
stimulates the neuron-rich tissue at the back of the eye (the
retina), sending patterns of electrical impulses to the brain
(specifically to a region of the brain known as the visual
cortex), where the signals must be processed and
interpreted to create what we see.

21. there is animal and human
evidence for 3 discrete
processing systems
“Although the visual processing mechanisms are not yet
completely understood, recent findings from anatomical and
physiological studies in monkeys suggest that visual signals are
fed into at least three separate processing systems. One system
appears to process information mainly about shape; a second,
mainly about color; and a third, movement, location, and spatial
organization.”
Human psychological studies support the findings obtained
through animal research. These studies show that the
perception of movement, depth, perspective, the relative size of
objects, the relative movement of objects, shading, and
gradations in texture all depend primarily on contrasts in light
intensity rather than on color.”
SOURCE: http://www.brainfacts.org/sensing-thinking-behaving/senses-and-perception/
articles/2012/vision-processing-information/

22. in the third system
(depth/location/movement)
“About 60 years ago, scientists discovered that each
vision cell’s receptive field is activated when light hits
a tiny region in the center of the field and inhibited
when light hits the area surrounding the center. If light
covers the entire receptive field, the cell responds
weakly.”
Another way to put this is: “the visual process begins by
comparing the amount of light striking any small region of
the retina with the amount of surrounding light.”
This process is enhanced by “lateral inhibition,” in which
all but the strongest signals are filtered out by the retina
before even reaching the brain. (Preference for edges.)
SOURCE: http://www.brainfacts.org/sensing-thinking-behaving/senses-and-perception/
articles/2012/vision-processing-information/

23. Our ability to, judge distance, move through space, avoid
obstacles,—these are all INFERENCES drawn from
information about contrasts between light intensity rather
than actual visual data—even though we perceive them
as properties of our vision.
This is ANOTHER REASON why the eye/camera idea is
completely misleading.

24. let’s summarize
The brain constructs your field of vision from electrical impulses
sent by the eye.
The eye collects data on
shape
color
position/location/movement
and these seem to be processed in the brain by three discrete
systems.
The raw data entering the third system has to do with differences in
light intensity. These signals are enhanced by the retina through
the process of lateral inhibition and are subsequently interpreted by
the visual cortex to produce our field of vision, which we experience
as continuous and compelling rather than as a series of
approximations of distance, size and depth via contrasts between
light and shadow.

25. J.S. COPLEY
Mrs. Ezekiel Goldthwait
oil on canvas
50 1/8 x 40 1/8 inches
This human perceptual
preference for “edges”—
areas of high contrast between
light and shadow—is also
exploited by artists wanting to
create convincing three-dimensional
illusions in their two-dimensional
art.

26. “blind spot” experiment
http://serendip.brynmawr.edu/bb/blindspot1.html
http://serendip.brynmawr.edu/bb/blindspot/
http://serendip.brynmawr.edu/bb/latinhib.html
http://dragon.uml.edu/psych/illusion.html

27. In this class we consider…
not the spectrum of light visible
to the human eye,
but our culturally bound sense
of what colors mean.

28. In other words, not what
vision is,
But in what human
beings have made
of vision.

29. M.C. Escher (Dutch, 1898 – 1972), Drawing Hands, 1948, ithograph, 11 1/8 x 13 1/8 in