Visual experiences aren’t always transparent
In 1976, when I delivered the John Locke Lectures
at Oxford, I often spent time with Peter Strawson, and one day at lunch he made
a remark I have never been able to forget. He said, "Surely half the
pleasure of life is sardonic comment on the passing show". This blog
is devoted to comments, not all of them sardonic, on the passing philosophical
show.
Hilary Putnam
Back on 6/11 (Escher Colors) I wrote;
“My own experience thus prepared me to accept one
of the points that Block makes: the view (common to ‘representationalists’ and
at least some ‘disjunctivists’ in the philosophy of perception) that the
phenomenal quality of a subject’s visual experience upon looking at (hearing,
feeling, smelling, etc.) a certain portion of her environment is exhausted by
the objective appearance-properties (e.g., looking such-and-such a shade from
such-and-such a point in space under such-and-such lighting conditions) of that
portion of the environment is untenable. This view is, of course, a strong form
of ‘naïve realism’, and while I think naïve realists are right to say that what
we see (hear, feel, smell, etc.) when we perceive objects and events in our
environment are properties of those objects and not properties of our qualia
(something Block also thinks is right, as his paper makes clear), it is a
mistake to say that describing what we perceive in objective terms also
completely describes the phenomenology of the perceptual experience.”
In today’s post I want to discuss an argument
representationalists (aka “strong representationalists”, and “intentionalists”) often use to defend
the view that I criticized, the argument from the “transparency” of phenomenal
character. Here is how a leading representationalist, Michael Tye, opens his
presentation of the argument:
“Representationalism is a
thesis about the phenomenal character of experiences, about their immediate
subjective ‘feel’. At a minimum, the thesis is one of supervenience: necessarily,
experiences that are alike in their representational contents are alike in
their phenomenal character. So understood, the thesis is silent on the nature
of phenomenal character. Strong or pure representationalism goes further. It
aims to tell us what phenomenal character is. According to the theory
developed in Tye 1995, phenomenal character is one and the same as
representational content that meets certain further conditions. One very
important motivation for this theory is the so-called “transparency of experience.” [1]
—and here is how he goes on to explain “transparency”:
“Focus your attention on the scene before your eyes and on how things look to you. You see various objects; and you see these objects by seeing
their facing surfaces. Sense- datum theorists claimed that the facing surfaces
of the objects are themselves seen by seeing further immaterial surfaces or
sense-data. The sense-datum theory is unacceptable, however, for a whole host
of familiar reasons. Intuitively, the surfaces you directly see are publicly observable physical surfaces. They are at varying angles to the line
of sight and varying distances away. They can be photographed. In seeing these
surfaces, you are immediately and directly aware of a whole host of qualities.
You may not be able to name or describe these qualities but they look to you to
qualify the surfaces. You experience them as being qualities of the surfaces. None of the qualities of which you are directly aware in seeing the various
surfaces look to you to be qualities of your experience.
You do not experience any of these qualities as qualities of your
experience. For example, if blueness is one of the qualities and roundness
another, you do not experience your experience as blue or
round.”
For normal adult viewers, this paragraph
does describe “how it seems”; in philosophers’ jargon, it describes part of the
phenomenology of visual experience.
But Escher Colors did criticize an
assumption that is clearly implicit in what Tye writes, the assumption that the
“qualities” I seem to perceive are
qualities that a physical surface could actually have, (NB: Tye, like Byrne
is a physicalist about colors). In Escher Colors I argued that there is no
such thing as “really” being the exact shade that something seems to be when I
look with my left eye (the right eye being closed) as opposed to “really” being the exact shade that it seems to be
when I look with my right eye (the left eye being closed); those “Escher
colors” may, phenomenologically, seem to be qualities of physical surfaces but they can’t be. That was the point of
that post. But the purpose of the present post is not simply to remind you of
that. Tye’s intention is to use the phenomenological “transparency” of visual
experience to argue for the thesis that “phenomenal character is one and the
same as representational content that meets certain further conditions”; and
for that purpose, transparency (understood as Tye does) needs to be a necessary
property of all visual experiences - an intrinsic
property of such experiences. The
purpose of this post is to argue that there is impressive empirical evidence
that transparency is not intrinsic, but
is the result of learning.
Held’s
experiments (1)
There is strong
experimental evidence that in certain cases, described by Richard Held in two
different series of experiments many years apart, some non-human mammals and
even some humans do not visually
perceive colors and shapes as “out there”. I conclude that “transparency” is (normally) the result
of early learning (but, contrary
to Block’s view, mentioned in my
previous post, not something we can override if we try and we know how to do
it. At least I see no evidence for this claim.) The first visual experiences
of many mammals, including both cats and humans, are not experienced by those
organisms as properties of surfaces “out there”. “Out thereness”, recognition
of things as having locations in places accessible to both sight and touch,
requires that the correlations between visual space and sensorimotor (tactile,
or “haptic”) space be learned. The
disposition to learn such correlations quickly may well have been selected for
in the evolutionary history of our visual and haptic systems, but some hours or
days of learning are still needed. Here is some background.
In 1963, when Richard Held and
I were colleagues at MIT, he showed me the following experiment that he and
Alan Hein performed[2]:
two kittens were placed in baskets that were at the opposite ends of a pole
that was free to rotate around a vertical axle[3]. One
basket had holes that permitted the kitten in that basket, kitten A, to push
against the floor and thus to determine how the basket would move, at least to
a limited extent. Kitten B’s basket had no holes; willy nilly, kitten B
experienced spatial motion when kitten A moved – the mirror image of kitten A’s
spatial motion, in fact - but no sensorimotor feedback. When kitten B was taken
out of its basket, it had no recognition of any sensorimotor affordances at
all. If one poked a finger towards its eyes, it stuck out its paws (an innate
reflex), but not in the direction of the approaching finger. If it were put
near the edge of the table, it would fall off (or would have fallen if there
were not something to catch it) as often as not. But when Kitten A was taken
out, it was able to position its paws in front of the threatening finger, it
never walked off the edge of the table, etc. The results strongly suggest that the kitten that had
not learned those correlations did not see the visual data it experienced as
“out there”, and so the phenomenal aspects of its visual experiences were not
transparent.
Held’s
experiments (2)
In 1688 William Molyneux sent a
message to the philosopher John Locke asking: “Suppose a man born blind,
and now adult, and taught by his touch to distinguish between a cube and a
sphere of the same metal ... Suppose then the cube and sphere placed on a
table, and the blind man be made to see: query, whether by his sight, before he
touched them he could now distinguish and tell which is the globe, which the
cube ...?”[4]
In 2011 a team of researchers including Held and led by
Pawan Sinha of MIT, published a negative answer to Molyneux’s question.[5]
Similar results were reported earlier by a group referred to by Held in “Visual-Haptic Mapping and the Origin of
Crossmodal Identity”[6]. The
research involved studying youngsters who had been blind from birth, after they
had lenses surgically implanted under the auspices of Project Prakash in India.
Here is the Abstract of “Visual-Haptic
Mapping”:
“We
found that the congenitally blind person who gains sight initially fails to identify
seen objects with their felt versions: a negative answer to the Molyneux
question. However, s(he) succeeds in doing so after a few days of sight. We
argue that this rapid learning resembles that of adaptation to rearrangement in
which the experimentally produced separations of seen and felt perceptions of
objects are rapidly reunited by the process called capture. Moreover, the
original ability to identify objects across modalities by the neonate may be
assured by the same process.”
—And
here is a description of the subjects studied by Ostrovsky et al:
“subjects’ responses were driven by
low-level image attributes; [when asked to point to objects] they pointed to
regions of different hues and luminances as distinct objects. This approach
greatly oversegmented the images and partitioned them into meaningless regions,
which would be unstable across different views and uninformative regarding
object identity. A robust object representation is difficult to construct on
the basis of such fragments” (Ostrovsky, Y., et al. 2009. “Visual parsing after
recovery from blindness”. Psychological Science 20, 1484-1491.
In sum, these subjects’ visual
experiences were anything but “transparent” to them. The representational
content of visual experiences is something we learn to recognize. It is not
intrinsic, and a fortiori not
identical with their phenomenal character.
[2] Held,
R. and Hein, A (1963) Movement-Produced Stimulation in the Development of
Visually-Guided Behavior. Journal of
Comparative and Physiological Psychology, vol. 56, 5: 872-876.
[3]
For a picture, see: http://pirate.shu.edu/~hovancjo/exp/kit_caro.htm
[4]
Morgan MJ. Molyneux's Question: Vision, Touch, and the
Philosophy of Perception. Cambridge University Press, 1977. Quoted by Held
in “Visual-Haptic Mapping and
the Origin of Crossmodal Identity”, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2749576/.
[5] Richard Held, Yuri
Ostrovsky, Beatrice de Gelder, Tapan Gandhi, Suma Ganesh, Umang Mathur & Pawan Sinha. “The Newly
Sighted Fail to Match Seen with Felt”, Nature
Neuroscience 14 (2011), 551-553.
[6]
Ostrovsky, Y., et al. 2009.
Visual parsing after recovery from blindness. Psychological Science 20,
1484-1491.
