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Kennedy, J. M. and Hammad, S. (2011, 2012) Cognition and representation: Picture perception . Chapter 5, pp. 63-74 in Verkoerperungen (“Embodiment”) Editors André L. Blum, John Michael Krois & Hans-Joerg Rheinberger, Max-Planck Institute for the History of Science, Berlin. Preprint 416, 2011. Full volume 2012, pp. 71-83. Diskussion pp. 84-88.


Abstract and Figures

Key problems of picture perception include inverse projection from the observer as an embodied vantage point, illusory effects on picture surfaces, the elements of pictures, the major geometry used to show space, the modalities of pictures and non­literal representation. Our suggestions are as follows: environments constrain inverse projection, perspective generates illusions in viewing pictorial surfaces, border elements produce apparent groupings, perspective perception uses elevation and azimuth ratios, touch and vision use the same spatial principles and pictorial metaphors use the same shapes in vision and touch. We also briefly mention expression in pictures.
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Key problems of picture perception include inverse projection from the observ-
er as an embodied vantage point, illusory effects on picture surfaces, the ele-
ments of pictures, the major geometry used to show space, the modalities of
pictures and non-literal representation.
Our suggestions are as follows: environments constrain inverse projec-
tion, perspective generates illusions in viewing pictorial surfaces, border ele-
ments produce apparent groupings, perspective perception uses elevation and
azimuth ratios, touch and vision use the same spatial principles and pictorial
metaphors use the same shapes in vision and touch. We also briefly mention
expression in pictures.
Introduction: Study ing perception
as a well formed problem
Picture perception had its advent with the arrival of parietal art (art on rock
walls) a little more than 50,000 years ago, possibly in Africa and later in areas
such as the Middle East, Asia and Europe. Its devices spread because they tapped
universals of perception.
What is a picture so it can be universally observed,
and what is an observer who can use a picture?
In theinverse projection” prob-
1 Heiko Hecht/Robert Schwarz/Margaret Atherton (Eds.): Looking into Pictures,
Cambridge, MA 2003.
2 Raymond W. Gibbs: Embodiment and Cognitive Science, Cambridge 2006; Robert
Hopkins: Touching Pictures, in: British Journal of Aesthetics 40/1 (2000), pp. 149−167.
John M. Kennedy and Sherief Hammad
John M. Kennedy and Sherief haMMad
lem, the observer is an embodied vantage point in a scene.
The observer has
specific abilities and the scene has well-defined characteristics. We will argue
that pictures are relative newcomers in the history of perception, so inverse
projection works well in observation of real scenes, but our perception of ele-
ments on picture surfaces has special features, some illusory. Indeed, the ele-
ments can be tactile as well as visual, since pictures make sense to the blind
literal copies and pictorial metaphors.
Projec tion, i nduction and surfaces
Bishop Berkeley recognized that a given shape entering the eye is a proximal
stimulus that could be caused by an infinite number of distal stimuli
and con-
cluded that inverse projection is impossible. Berkeley argued we must learn to
supplement vision by touch. Alas, data in vision plus touch is just more data. A
combination of vision and touch is just as subject to an infinite number of expla-
nations as visions data alone is. Likewise, to add inferences from memory
would just be to add memory data. (Indeed, the memory has no clear origin,
making it an uncaused cause, deus ex machina.)
The way Berkeley set up inverse projection is ill-formed. It becomes
well-formed if we set the observer in a constrained environment. The first task
of embodiment theory is to embody the environment.
It precedes the observer.
In Berkeley’s induction problem no constraints are given. If there are no
constraints given in the statement of the problem, then there are no constraints
on the solutions. This is a tautology, like saying “white is white”. If there are no
constraints, there are no constraints. If there are no constraints on the relations
between the proximal and distal stimulus then – no surprise there would be
no constraints on the distal stimulus. The only way to justify the contents of
mind is to situate it in an environment – to embody it as mind in place.
3 Dominic M. M. Lopes: Art Media and the Sense Modalities: Tactile Pictures, in:
Philosophical Quarterly 47/189 (1997), pp. 425−440; id., Sight and Sensibility:
Evaluating Pictures, Oxford 2006.
4 Elisabeth Salzhauer Axel/Nina S. Levent (Eds.): Art beyond Sight: A Resource
Guide to Art Creativity, and Visual Impairment, New York 2003; Yvonne Eriksson:
Tactile Pictures: Pictorial Representations for the Blind 17841940, Gothenburg
1998; Morton A. Heller/Soledad Ballesteros (Eds.): Touch and Blindness: Psychol-
ogy and Neuroscience, Mahwah, NJ 2006.
5 Igor Juricevic/John M. Kennedy: Looking at Perspective Pictures from too Far, too
Close and just Right, in: Journal of Experimental Psychology: General 135/3 (2006),
pp. 448−461; John M. Kennedy: Drawing and the Blind, New Haven, CT 1993.
6 Gibbs: Embodiment (as fn. 2).
7 Ibid.
Cognition and repreSentation: piCture perCeption
Let us allow that, prior to the existence of pictures, surfaces of objects
were textured and typically fairly regularly textured. The idea that surfaces are
the key to perception of shape I take from W. K. Clifford, 19
century British
mathematician, and the idea that textures allow us to see surfaces is due to
Wolfgang Metzger, 20
century German perceptionist.
The idea that texture is
relatively uniformly distributed across natural surfaces and gives us informa-
tion about distance is from James J. Gibson, 20
Century American realist.
idea that the basic surface for perception is a receding ground plain we take
from Piero della Francesca, 15
century Italian.
Surfaces and texture
Shapes are flat (zero curvature) or curved (positively or negatively), with matter
filling one side. The unfilled side is the location of possible vantage points. Filled
matter forms domes (convex matter or positively curved), bowls (concave mat-
ter, or negatively curved) and saddles (concave in one dimension and concave in
the orthogonal). Pairs of surfaces form convexities such as roofs and concavities
such as corners of rooms. A vantage point can be enclosed by a concave corner.
A vantage point above a roof has both surfaces exposed to it, but only one sur-
face is exposed at a vantage point to the side of a roof, and the other surface,
behind the exposed one, is hidden or “occluded”. The exposed surface is a front
surface, and the occluded surface is a rear surface. Similarly a curved convex
surface like a hill can have one part of its surface exposed to a vantage point, and
the other part behind – a front exposed surface and rear occluded surface. The
division between the front and rear surfaces is an occluding boundary. It is an
occluding edge, for a flat surfaced roof, and an occluding bound, for the rounded
brow of a hill. Inevitably, an occluding boundary is set against a background.
The roof or hill may be silhouetted against the empty sky, or there might be a
well-defined surface such as a wall of a tall building or a high cliff face.
The set of vantage points is the medium, and the distribution of matter
defines a set of surfaces surrounded by the medium. From each vantage point,
each point on a surface has a direction and a distance. The medium for terres-
trial surfaces is generally air and fairly uniform, allowing rectilinear propaga-
tion of light, so the direction from which proximal light comes generally indi-
cates the direction of the distal surface from which it came. Special cases
8 John M. Kennedy: A Psychology of Picture Perception, San Francisco, CA 1974; id.,
Drawing (as fn. 5).
9 James J. Gibson: The Ecological Approach to Visual Perception, Boston, MA 1979;
Kennedy: Picture Perception (as fn. 8).
10 Igor Juricevic: Looking at Perspective Pictures (as fn. 5).
John M. Kennedy and Sherief haMMad
including mirrors and air above heated objects are well marked and distinctive
mirrors are limited in size and the light is unstable in unique ways. In day-
time, the surfaces are illuminated by sunlight, which they reflect to varying
degrees, sending light to the vantage points.
Any pattern in the light at a vantage point is due to variation on surfac-
es. Surfaces of a particular kind of matter have distinctive textures, relatively
uniformly distributed stochastically regular – and can produce highly-signif-
icant texture gradients in light at a vantage point above them.
Consider a flat ground surface stretching to infinity – to the horizon. Let
its texture be a kind of mottling, meaning there are areas reflecting much of the
incident light sky and poorly-reflecting areas interspersed. Each mottle will
project light to a vantage point above the ground. The mottling near the van-
tage point will project a large solid-angle of light. It has a large angular sub-
tense. Similar-sized mottling further away on the ground will project a smaller
solid angle of light a smaller angular subtense. Mottling still further away
will project even smaller. Evidently, the mottling produces a gradient in the
light at the vantage point.
Consider a path of similar-sized mottles stretching straight away from
the vantage point. Each of the mottles projects a width or azimuth dimension as
well as an elevation dimension related to its distance or “depth. The elevation
subtense shrinks at a quadratic rate with distance. The width dimension has a
subtense that also shrinks with distance, but at a linear rate. Hence rounded
mottles on the ground just below a vantage point project equal subtense angles
in elevation and azimuth, but rounded mottles in the distance project much
slimmer in elevation than in azimuth. That is, from a distance they project what
a slim ellipse would from underfoot.
The relation between quadratic and linear foreshortening is highly spe-
cific to a flat ground and its mottling. Optic information is present if one thing
(a proximal optic pattern) is specific to another (a surface). Far from being infi-
nitely ambiguous, light at a vantage point in an environment of textured sur-
faces is highly specific to the layout of surfaces around the point, and therefore
Texture gradients projected by curved surfaces modify the linear and
quadratic components. A bowls curvature is signalled by a decrease in the quad-
ratic and linear components since if the vantage point is at the centre of the bowl
all the mottling projects equally in elevation and azimuth. At a rise in the
ground plain the rate of change of distance decreases. A sudden change from a
ground plain to a rise is specified by a sudden change in the quadratic and linear
components of the texture gradients. If we are standing at the back of a horizon-
tal wooden stage which has at the front a large step down to a horizontal wood-
en floor, from our vantage point the step down from floor to stage is likely indi-
Cognition and repreSentation: piCture perCeption
cated by an abrupt change in the projected texture density. Planks in the stage
recede from us, and project a texture gradient, with a quadratic rate of change
with distance. The same rate of change is projected by planks in the wooden
floor. But the step down at the edge of the stage is specified by an abrupt in-
crease in the density of the texture.
Perception responds to texture gradients and in principle can respond to
any information. It can respond to information for temporal sequences, for two
events having different durations, and for causality in collisions. It can respond
to information for emotional expressions, given species-specific indicators of
emotion. It can respond without calling on memory since evolution could have
selected the observer’s response. It is not so much that there are a xed set of
dimensions defining perception as that the proximal input carries many kinds
of information, and bodies respond to some of these.
Scene information exists before pictures. Pictures come into existence to
capitalize on the information to show a scene. People change the texture on
surfaces, put elements on the surface, and arrange them so light reflected from
them mimics the light from scenes. Nature evolved us over aeons of years to
deal with scenes accurately but pictures are creatures of only some thousands,
so perception of pictorial elements is novel, subject to major illusions.
Illusions on pic t ure surfaces
Given the interests of the earliest cave-dwellers, we can assume that sharp,
acute-angled objects were seen for what they are, and blunt, obtuse-angled ob-
jects seen as such. But with pictures, acute angles and obtuse angles on a surface
may both stand for right angles. Evolution did not prepare us for this.
Consider Figure 1. Atop each picture of a cube is a quadrilateral with an
obtuse angle that stands for a right angle. Subjects underestimate the obtuse
angles on the picture surface by as much as 35 degrees. Similarly, they mis-
judge the acute angle on the left and right sides of the quadrilateral, in this case
overestimating the angle.
The obtuse and acute angles are reported to be closer to 90 degrees than
is truly the case. The illusion is most strong when the obtuse angle is about
155 degrees and the acute angle about 25, with the depicted cube tilt about 30
The angle illusion is likely caused by features indicating the quadrilat-
eral depicts a tilted shape. The picture must suggest a tilt and a shape. For exam-
11 Sherief Hammad/John M. Kennedy/Igor Juricevic/Shazma Rajani: Angle Illusion
on a Picture’s Surface, in: Spatial Vision 21/3 (2008), pp. 451462.
John M. Kennedy and Sherief haMMad
ple, perspective governs the projection from the distal, depicted object. The
quadrilaterals conform to the rule of orthogonals elevation decreasing as a
quadratic function and azimuth as a linear function and suggest a square.
Plus, the Y-junctions suggest a cubic corner. Indeed, each junction could be a
projection of a right angle. Likely, indicators of a slanted square surface are all
most plainly evident when the distal cube is at an intermediate slant to the pic-
ture surface (between 20 and 70 degrees to the picture plane), and this is when
the angle illusion is greatest.
Perspective provides information about the distal square’s tilt. Any in-
formation about that tilt should create illusion in perceiving the form on the
picture surface. Indeed, the depicted form does not have to be a well-formed,
familiar or symmetrical form such as a square, nor does the projection have to
be linear perspective. The depicted angle can be acute and the projection can be
parallel projection, as in Figure 2. The form suggests two cubes stacked togeth-
er, with a diagonal line across the top. Its distal angles are 27 and 63 degrees.
Figure 1 Two drawings of cubes. The obtuse and
acute angles showing the top face are misperceived.
Figure 2 Double-cube figure with a
diagonal line. Observers misperceive
the acute angles on the picture
surface showing corner angles in the
triangle atop the cubes.
Cognition and repreSentation: piCture perCeption
Observers judging the surface angles report angles closer than is correct to
these distal angles.
The illusion is present given effective information for a plane tilted in
depth. The tilt can be suggested by making the cube be a tower, a double-cube in
height. It is also present for a block that is only a quarter-cube in height. Remark-
ably, the illusion is present at equal strength for the regular cube, the double-
cube and the quarter-cube, an 8-fold change in size. This suggests the illusion is
driven by indicators of tilt, not by the lengths of the lines under the target
quadrilateral on the picture surface.
The illusion is also present at full strength when the cube is animated,
tilting back and forth by 5 degrees. That is, 3D-tilt apparent-motion informa-
tion does not reveal to the observer the angles on the picture surface. Nor does
it enforce an especially large illusion. Rather, any information which reveals
the tilt generates the illusion.
The illusion is to do with the apparent shape of the top form. It is not just
an angle illusion. Hence, it is present for depictions of tops of cylinders just as
much as it is for tops of cubes. Ellipses depicting the circular tops of cylinders
are misjudged severely at intermediate tilts. They appear more circular than is
These errors are not due to memory for cubes and cylinders in the sense
that observers recall how cubes and cylinders have square and circular faces,
and classify and report the picture surface forms as such. Rather than reporting
perfect squares and circles, observers describe forms intermediate between the
surface and depicted forms. In Arnheim’s terms, these are compromises, and in
Sedgwick’s terms, these are due to crosstalk between information for the depict-
ing surface and information for the depicted scene.
The general lesson is that evolution situated observers in an environ-
ment with useful information and humanity introduced a new medium for pre-
senting that information, but the new mediums properties are not seen veridi-
cally. The new kind of display contains illusions, in which observers see surface
properties biased towards what the surface depicts as distal properties.
12 Igor Juricevic/Shazman Rajani/Sherief Hammad/John M. Kennedy: “Projection
biases perceived angles on a picture surface.” International Conference on Cortical
Mechanisms of Vision, Centre for Vision Research, York University, Toronto, CA-
ON June 19–23, 2007.
13 Sherief Hammad/John M. Kennedy/Igor Juricevic/Shazman Rajani: Ellipses on
the Surface of a Picture, in: Perception 37/4 (2008), pp. 504510.
14 Id., [short title 2008a OR 2008b?] (as fn. 11 OR 13 ??)
John M. Kennedy and Sherief haMMad
As cave artists discovered,
outline shows surface edges, and line may have
more than one contour but can stand for one edge. Figure 3 shows foregrounds
and backgrounds using lines for boundaries of flat and curved surfaces, a convex
near corner of the house and a concave corner of the walled-in garden. A line
showing a border of a shadow cast by the house on the ground does not create an
impression of darkness, but lines showing surface edges trigger clear impres-
sions of foregrounds and backgrounds. Therefore, lines in outline drawings
should be described as showing surface edges, not just any borders.
One notable use is the lines for the near wall of the garden. The top line
of the wall shows an occluding edge of a at surface. The lower line shows a
concave corner formed by the wall and the ground. If we see the line as showing
a wall sitting on a supporting surface, the foreground horizontal surface contin-
ues underneath the wall and comes into view above the line for the top of the
A line can stand for an edge of a surface, at an occlusion, or for edges of
two surfaces, at a corner. That is, foreground surfaces can be depicted on one
side of a line, or both sides. The background can be indefinite, as in the case of
the sky above a roofline or hill, or well-defined and distant, as in the case of a
ground evident behind the top of a wall, or well-defined and close, as in the case
of a desktop immediately behind an edge of an envelope. The line itself can be
15 Björn Laursen: Blyertsteckning. En introduction i kreativt bildarbete [Pencil
Drawing: An Introduction to Creative Picture-Making.], Stockholm 1990.
Figure 3 Surface edges shown by lines include a foreground surface continuing
behind another foreground surface.
Cognition and repreSentation: piCture perCeption
the foreground with a distant background on either side, as in the case of a wire
silhouetted against the sky. Or the foreground shown by the line can have a
near surface as background on one side, as in the case of a thin frame for specta-
cle glasses, or both sides, as in the case of a rail, with ground on either side of the
rail, or a toothpick lying on the ground.
The line itself can also show the background, as in depicting a crack in a
fencepost, with an indefinite distance to the background. In this case, fore-
ground surfaces defined by the fencepost lie on either side of the line. The back-
ground shown by the line can also be close, as in the case of a line depicting a rut
or the mortar between bricks. The line itself can also be background for a sur-
face on one side of a line, as in the case of a frame in which the line stands for a
recessed frame around a raised plaque – a back plate for the foreground plaque.
Colour can appear to fill a volume, be on a surface or be filmy. A sky at
an indefinite distance appears in perception as a volume colour, and a well-de-
fined background appears as a surface colour. A line can also depict an edge of a
films surface, and an outline drawing can even depict two films intersecting
each other, forming a corner in which both foreground surfaces continue past
their intersection and behind each other. In this case, the films are partially
Put systematically, lines have two borders, internal space between the
two borders, and external space on either side. The internal and external spaces
define three regions left side, middle and right side in the case of a vertical
line. Any of the three regions can be a foreground surface, or a well-defined or
indefinite background three options. This yields 9 combinations. Any one of
these options can be depicted, save one, which is a notable impossibility. A pos-
sible combination is a foreground line with background on one side e.g. showing
a wire framing spectacle lens. The impossible combination is a background
shown on the left side of the line, plus a background shown by the line itself plus
a background shown by the right side of the line. Some region of the line has to
be shown as foreground if there is to be background. There cannot be a follower
without a leader.
The use of a line to show foreground on one side involves what Edgar
Rubin called figure-ground.
Figure is actually foreground surface and ground
is background surface. Rubin also described an apparent referent of the line in
an even-breadth phenomenon” or “jaevnbrede fenomen” in his native Danish
(Rubin, 1949).
A line can have two differently-shaped contours, and vary in
thickness but give an impression of an object uniform in thickness. An example
16 Edgar Rubin: Synsoplevede figurer, Copenhagen 1915.
17 Id.: Experimenta psychologica, Copenhagen 1949.
John M. Kennedy and Sherief haMMad
using thick lines for clarity is in Figure 4, especially in the lower part of the
rightmost line in each window. Part of the line is bent like a knee, with a round-
ed kneecap on the left side and a sharp v-shaped fold on the right.
At each bend in a meandering line the two contours on either side of the
line have different shapes. Nevertheless, the line appears to have a uniform
thickness. Perception matches the contours on either side of each bend, choos-
ing contour matches a uniform distance apart. At the knees in Figure 4, the
sharp point of the V is matched with rounded-kneecap contour horizontally
across from the point. Above the V point, the contour matches are at an oblique
close to 45 degrees in orientation, running 10 o’clock to 4 o’clock. Below the V
point the matches are at an oblique again, 7 o’clock to 2 o’clock, an oblique al-
most 90 degrees to the 10 to 2 o’clock oblique above the point. The matches are
chosen to maintain an even separation between the contours, and an even-
breadth for the depicted trail.
Drawings in touc h
Foreground, background, and edge referents of line are available to touch in the
blind as much as they are to vision in the sighted. A surface is tangible as well as
So too are well-defined, empty and filmy backgrounds. Cave artists
discovered line depicts surface edges for the sighted, and blind people are now
discovering outline.
Figure 5 is a drawing by a blind woman, EW, of a tree. It shows the
highly-textured trunk and the tree’s branches and leaves. It is dated (2006) and
signed with her initials.
18 Susan J. Lederman/Roberta L. Klatzky: The Hand as a Perceptual System, in:
Kevin J. Connolly (Ed.): The Psychobiology of the Hand, London 1998, pp. 16−35.
Figure 4 Thick lines that appear like trails of toothpaste, with uniform thickness along
their length.
Cognition and repreSentation: piCture perCeption
Figure 5 Drawing of a tree in
Australia by EW.
EW began drawing extensively as an adult. She lost vision completely at
1 year of age. In her 30s, she was encouraged to begin drawing by Elke Zollitsch,
a grade school teacher. EW is self-taught, with encouragement from Zollitsch
but no instruction.
Figure 6 is a picture of woods in Germany – Thüringer Wald. This is a
highly expressive and effective picture in many ways. Several trees are shown,
19 Elke Zollitsch: I Know where I Am, Waldkirchen 2003.
Figure 6 Thuringer Wald, by EW. V-shaped marks suggest bird calls.
John M. Kennedy and Sherief haMMad
Figure 7 Advent wreath by EW. The candles are shown
in fold-out style.
with branches and leaves, standing on irregular ground, shown by the pair of
wavy lines at the base of the picture. The criss-crossing branches are drawn
expressively. The solidity of the ground is suggested by texture between the
wavy base lines. Joining the trees are flowing lines showing the wind. Between
the trees are marks, many V-shaped, which have a surprising and enlightening
function. They stand for bird calls. If the lines standing for surfaces and edges
of tree trunks, branches and leaves are literal, bird-call lines are metaphoric.
The V-lines suit short chirps, brief calls. The Vs share brevity, compact abrupt
changes, and up-and-down features with the pitch of calls.
Figure 7 shows the first drawing EW made after being encouraged to
take up drawing as an adult. It shows an Advent wreath. Of special interest here
is that the candles are shown in what can be called a fold-out” style. The upper
candles are shown by vertical lines, but the lower candles are shown by horizontal
lines because vertical lines would compete for space with the lines for the foli-
age of the wreath. The fold-out technique is commonly used by sighted grade-
school children in this fashion.
Evidently, the development of drawing in the
blind and the sighted may take the same course.
20 Gibbs: Embodiment (as fn. 2); John M. Kennedy: Metaphoric Drawings Devised
by an Early-Blind Adult on Her Own Initiative, in: Perception 37/11 (2008),
pp. 1720−1728; Chang Hong Liu/John M. Kennedy: Form Symbolism, Analogy
and Metaphor, in: Psychonomic Bulletin & Review 4/4 (1997), pp. 546−551.
21 Andrea Nicholls/John M. Kennedy: Drawing Development: From Similarity of
Features to Direction, in: Child Development 63/1 (1992), pp. 227−241.
Cognition and repreSentation: piCture perCeption
Inverse projection is undertaken in a natural and constrained environment by
an observer embodied as a vantage point with capacities to use outline. Infor-
mation due to the constraints is used to make pictures, rst introduced to the
environment some thousands of years ago, a trifle in evolutionary terms. Ob-
servers have perceptual equipment that was developed over aeons for the nat-
ural environment, and, as a consequence, the equipment is susceptible to illu-
sions in observing elements acting in the novel fashion introduced by pictures.
Perspective is the major geometry providing information about space and it
gives rise to illusory perception of angles and areas in pictures depicting tilted
objects. Both touch and vision are modalities for pictures, since both perceive
surfaces and both accept lines as showing surface boundaries. In pictures show-
ing surfaces and edges, non-surface referents such as bird calls can be shown by
line shapes, and if surface edges are described as depicted literally, the other
referents are metaphoric.
Ulrike Draesner When did the blind explain what their pictures meant?
Afterwards? Or did they do it while they were drawing?
John M. kenneDy I asked Esref to explain his drawing while he was draw-
ing. He said: “I can’t do that. I cannot talk and draw at the same time.So he
draws first and then explains. His explanations are often very simple. He is not
very educated, so he has some skill – a little – in writing and he has some math-
ematics, but not very much. On the other hand Eriko has a master’s degree. In-
terestingly, unlike Esref, she can’t draw in perspective. She is like an eight or
nine years old sighted person, in that respect. But on the metaphoric side of de-
picting she is incredibly advanced.
Ulrike Draesner What about the guitar-picture, when did she explain it?
John M. kenneDy A couple of months after drawing. She was in Mexico
and came back with about seventeen drawings. I met her a couple of months
after and she started showing me her pictures. And of course I almost fell down.
This work is just astonishing. As an experimenter, however, I am not allowed to
show her how excited I am. Rather, I must sit there and say: “Ok, would you
explain this line. What is in this picture? Thank you very much.And then I
write down what she says. But the excitement was incredible.
anDré l. BlUM Has the brain activity of your subjects been assessed by
brain scans?
John M. kenneDy Alvaro Pascual-Leone at Harvard performed the scans
of Esref and I gave advice on what the researchers should ask Esref to do while
he was in the machine. When he was thinking about drawing and perhaps even
actually drawing, the language area shut down and the visual part of the brain
lit up like a christmas tree. Now, that visual part is a spare computer, so to say,
since Esref never had any eyes. It normally gets visual input, but not in Esrefs
brain. It gets recruited by the rest of the brain to solve interesting problems.
Presumely the same thing is happening for the deaf. The auditory area is a
spare computer, waiting to do something. And you can invade it and use it for
various tasks.
anDré l. BlUM There is an animal experiment which goes in the same di-
rection. Sharma and other members of a research group working at the Massa-
chusetts Institute of Technology cut the optic nerves of young ferrets and im-
planted the nerves into the auditory and the language” center.
the ferrets could see. But they saw with their auditory center. And while they
were seeing they switched on their visual centers as well, although the optic
nerves did not enter there.
John M. kenneDy Well, clearly that’s related to the Esref imaging experi-
ment. Johannes suggested to me over lunch that what we should do with Esref is
use Transcranial Magnetic Stimulation (TMS), shut down the language center,
and see if it makes any difference. Then we should shut down the visual center,
and see if this makes any difference. What might happen, given all the evidence
we have, is that after shutting down the language center, he’ll still draw in
three-point perspective. But shut down the visual center and he will draw at a
very primitive level. I think that’s a wonderful prediction. Also we should ask
Eriko to consider being tested in a TMS machine in Germany or Switzerland. It
might be terrific to work with her. By the way, somebody in Canada has been
given money to write a play about pictures and the blind. She has decided to
write about Eriko. Very challenging theatrically: How do you show all this tac-
tile stuff with a theatrical production? I think it is really interesting challenge.
John M. krois Peter Brook did Oliver Sacks already, so … by the way, you
said that parts of your work are controversial, could you say a little more about
John M. kenneDy In Québec a woman said after my talk “what you’re do-
ing is unethical. It’s unethical to have people who are blind dealing with pic-
1 Vgl. Michael Merzenich: Cognitive Neuroscience: Seeing in the Sound Zone, in:
Nature 404/6780 (2000), p. 820.
John M. Kennedy and Sherief haMMad
Three of my most serious rivals in tactile perception research think that
tactile pictures for the blind just cannot work. And touch is not meant for pic-
tures, they argue. Touch is meant for things like texture and solidity. Also they
have a study showing that blind people dont understand pictures. It turns out
that they have an identification rate in their study of about twelve percent. And
most of the early studies of picture-recognition by the blind, with raised-line
drawings, also have recognition rates of twelve to fifteen percent. So what are
you going to say? Is glass the one quarter full, or three quarters empty? A lot of
people say its three quarters empty. But then, consider this. When you first
deal with pictures you might start off with scribbles. And then you improve,
and this may occur rapidly. I have seen blind people increase from mere scrib-
bles to drawing, to the level of about a five-year-old-sighted person, in a matter
of minutes. First, they scribbled and said: “That’s no good. Im going to draw it
this other way.And then they started to put in one shape that is right. And the
rest still was scribbled. And then they said: “No, that’s no good.And then they
started to put in two shapes, side by side. Both of which were correct. A true
form for the object and an incredible developmental advance.
I gave a talk in Madrid and said: “This blind person drew an eagle and
did it from memory”, and wham, a hand went up: “What do you mean?” I ex-
plained what I meant: The person drew it from memory. They had a model, a
little brooch with an eagle on it and the blind person wanted to draw this eagle.
The eagle wasnt there and the person did it from memory.
I dont know why: three journals in a row, this year, rejected a paper on
Eriko. Two editors just said: “No, we wont do this.And the third editor said:
“Look, if you get the empirical work published somewhere we will consider an
article on the theory. But we’re not gonna touch a paper when you have both the
theory and the empirical work in one paper.” I dont quite understand that.
I used drawing paper made in Sweden. The Swedes have now abandoned
making this drawing-paper because, they say, “blind people do not understand
pictures”. Luckily the Norwegians have taken on the task.
One last thing: A woman from Copenhagen made a small book for blind
people. It was about little creatures going around in the world. She wanted to
put realistic illustrations in. And the Scandinavian organizations for the blind
said: “If you put realistic pictures in the book, we will not buy it.So she had to
put abstract pictures in, like a triangle and a square and a line. And then they
said: “Ok, we’ll buy that.
So, as far as I can tell, this work is incredibly controversial and you just
have to keep following the evidence. Gibson, my advisor, wrote in the early
nineteen fifties: “Blind people cannot understand pictures.He came to my house
in the nineteen seventies. He came in saying: “Blind people cannot understand
pictures.” He went out two hours later saying: Of course blind people must be
able to understand pictures.” Id like a lot of the critics to make that switch. And
to offer more helpful comments than simply no, not possible!
BarBara naUMann I’m grateful for the impressive material you showed
us. I was impressed by the first cube you showed, the cross-shaped one. Its like
an unfolded cube, a perfect abstraction of what a cube is when you take it apart.
My question is: I read about blind people working as photographers. How can
blind people orient themselves with respect to picturality when there is a tech-
nical medium between their body and whatever they want to visualize?
John M. kenneDy Many blind people have perfectly ordinary minds. And
they hear about art and photography. And they are deeply curious about all
these things that sighted people are doing. And they say: “I’d like to learn about
it.And so they want to get involved. Coming out soon is a twenty volume work
on art history for the blind. Wonderful stuff. And blind people ask: “What is
this thing that you call a camera, what does it do?” “Ok. You point it this
way.“What are you doing? Show me, how do you hold it?” “Oh, you do
this.” – “How do you orient the object? Let me try.” And they try and go “snip,
snip” just like any child would. Then the pictures are produced, and they say:
“What’s in this picture? How was I holding the camera when I took it?” And
they think about what they were doing. A lot of sighted people say: “You know,
I would never have taken that picture. That’s an interesting one, that’s differ-
ent.Because we tend to use a certain style when we are taking pictures, but
they will do a greater variety of things. A lot of it is accidental, of course, but
they are also producing interesting work, driven by basic human curiosity.
Some go on to have exhibitions.
Felix ingolD I have a question concerning dreams. Experiments were con-
ducted in people who were brain injured so that they could only see peripher-
ally. In their dreams, however, most of them had complete vision. So, how do
those people dream who are completely blind?
John M. kenneDy There are many studies on blind people dreaming. If
you lose vision you will continue to dream in full colour and 3D for two or
three years. But, more and more, you will dream without visual imagery. If you
started off totally blind you would still dream. But your dreams would be
things like: “I was walking down the stairs.And if people ask you about it, you
will describe the space, the timing, the motion, the echoes and the texture of the
floor, the size of the hall − was it narrow or wide? That sort of things. Of course
it might be possible that their dreaming was in full colour and they do not know
how to describe it. This is unlikely, but also it would be very hard to nd out.
John M. Kennedy and Sherief haMMad
anDré l. BlUM I knew a blind person who said that she could feel light and
dark colours with her hands. Did you observe that as well?
John M. kenneDy I was actually a subject in an experiment on that. And it
turned out I have the same colour deficiency in my fingers that I have in my
eyes. But I still dont believe it. I think it is the so-called nose-peek phenome-
non. Its very hard to get a visual mask that is a perfect fit to the bridge of the
nose, and some photons get past the mask and trigger receptors. Thus, experi-
ments on sighted people are subject to criticism. And I am dubious about the
studies on the blind. I would have to examine this further, but prima facie I do
not believe it.
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Full-text available
Picture Perception (as fn. 8)
  • Kennedy
Kennedy: Picture Perception (as fn. 8).
Looking at Perspective Pictures (as fn. 5)
  • Igor Juricevic
Igor Juricevic: Looking at Perspective Pictures (as fn. 5).
What's in this picture? How was I holding the camera when I took it?" And they think about what they were doing. A lot of sighted people say
  • M John
  • Kennedy Many
John M. kenneDy Many blind people have perfectly ordinary minds. And they hear about art and photography. And they are deeply curious about all these things that sighted people are doing. And they say: "I'd like to learn about it." And so they want to get involved. Coming out soon is a twenty volume work on art history for the blind. Wonderful stuff. And blind people ask: "What is this thing that you call a camera, what does it do?" -"Ok. You point it this way." -"What are you doing? Show me, how do you hold it?" -"Oh, you do this." -"How do you orient the object? Let me try." And they try and go "snip, snip" just like any child would. Then the pictures are produced, and they say: "What's in this picture? How was I holding the camera when I took it?" And they think about what they were doing. A lot of sighted people say: "You know, I would never have taken that picture. That's an interesting one, that's different." Because we tend to use a certain style when we are taking pictures, but they will do a greater variety of things. A lot of it is accidental, of course, but they are also producing interesting work, driven by basic human curiosity. Some go on to have exhibitions.