the organism to distinguish between exafferent signals

allowing
304 Notes to Pages 89–111
the organism to distinguish between exafferent signals (due to the motion of the
environment) from reafferent signals (due to the organism’s own motion). According
to corollary-discharge theory, the copy of the motor signal directly inhibits
the action of any functional unit (such as the optokinetic unit) that would
compensate for reafference by blocking the relevant action (as would an unchecked
optokinetic reaction). In efference-copy theory, on the other hand, a copy
of the motor signal is passed on by the relevant functional unit (e.g., the optokinetic
unit) as if it were a command from that unit. This allows the efference copy
and the reafference to cancel each other out. As Gallistel notes, however, the difference
between the two theories emerges only when reafference is abnormal.
5. For interesting and provocative discussion of some of the ontological implications
of ecological optics, see Reed 1987.
6. See also Rock 1975, 124–129.
7. See further the experimental evidence reviewed in the next section.
8. It is important to recognize the differences between misperception and perceptual
illusions. In addition to the familiar examples of visual illusions, like the
waterfall illusion, there are well-documented cases of artificially induced disorders
of bodily perception in which subjects report experiencing limbs in anatomically
and physically impossible positions (Lackner 1988). These are fundamentally different
from the misperception of affordances, because there is no way in which
they involve the pick-up of misinformation. In neither the proprioceptive cases
nor the visual cases is there a direct pick-up of information from the optical flow.
The perceptual systems are confronted with artificially induced sensory input that
they are forced to make sense of in any way they can.
9. The source for this is, of course, Perry 1979. For an opposed view, see Millikan
1990.
10. I am referring here to the level of autonomous nonconceptual content, in the
sense brought out in chapter 3.
11. I will discuss more complicated forms of instrumental protobeliefs in chapter
7. These emerge with the advent of memory.
12. See also Neisser 1991, Butterworth and Hicks 1990, and the papers collected
in Neisser 1993.
13. Comprehensive reviews will be found in the essays collected in Neisser 1993
and Rochat 1995.
14. I have discussed the philosophical significance of neonatal imitation from the
viewpoint of applied ethics in my 1996 essay.
15. Through the course of their development there are interesting variations in
the extent to which infants are susceptible to discrepant visual information. Experience
in sitting and crawling decreases susceptibility. See Butterworth and Hicks
1990 for further discussion.
16. This is not to rule out, though, the possibility that the first-person contents
of perceptual experience can be understood in terms of the states of visual-
Notes to Pages 113–129 305
processing subsystems in the brain, and that the states of such subsystems might
be representational and have content (Bermu´ dez 1995e). My suggestion is simply
that these subpersonal representational states, despite having contents, will not
have first-person contents.
Chapter 6
1. I am following closely the general introduction to Bermu´ dez, Marcel, and
Eilan 1995.
2. Such reasons are discussed by Anscombe (1962), who develops a position ultimately
derived from Wittgenstein (see Budd 1989).
3. In this and the following I will drop the explicit restriction to conscious
somatic proprioception. Unless there is any indication to the contrary, I will
use ‘somatic proprioception’ to refer only to the conscious modes of somatic
proprioception.
4. Although Shoemaker himself does not explicitly consider somatic proprioception,
he does explicitly argue for the Humean conclusion that the self cannot be
the object of any form of inner perception, as in the object-perception model.
5. When Shoemaker continues his discussion of the object constraint on pp. 256–
257, he modulates into what I am calling the multiple-objects constraint by defining
a notion of ‘object awareness’ in such a way that it must be possible for one
to bear it to a range of different objects.
6. It is important to distinguish exploratory or active touch from passive touch.
It is well known that the tactile discrimination of differently textured surfaces is
greatly increased when the finger moves relative to the surface, but it does not
seem to matter whether the movement is carried out by the subject or not. For
more complicated discrimination tasks, such as the discrimination of threedimensional
shapes and the determination of their structural and material properties,
however, active movement is essential (Gordon 1978, Lederman and Klatzky
1987).
7. The physiology of exploratory or active touch has been well researched, at
least with respect to the hand (Gordon 1978). Active touch depends on the joint
processing of proprioceptive and exteroceptive information. Proprioceptive information
about the movement of the hand is required so that predictable information
stemming from the subject’s own movement can be separated out from the
novel information about the contours of the object.
8. Of course, this is subject to the proviso that the behavior really is intentional.
For further discussion, see Meltzoff 1993 and Bermu´ dez 1996.
9. It is not yet known whether the process of coordinate transformation proceeds
in a hierarchical fashion, with each representation actually computed in increasing
order of complexity, or whether there is a single highly distributed bodycentered
representation that can integrate signals with different coordinate
frames.
306 Notes to Pages 132–141
10. Moreover, as shown by the movement errors discussed in Ghez et al. 1995,
visual information about initial limb position (and not just the position of the
target) has an essential role to play in controlling action. Both visual and proprioceptive
information are integrated at every stage of visually guided reaching.
11. For further discussion, see the papers in part 1 of Eilan, McCarthy, and
Brewer 1993.
12. Of course, it is possible to imagine complicated scenarios in which one’s proprioceptive
system is hooked up to another’s body so that misidentification is possible.
This is explored in Armstrong 1984 and Cassam 1995. As Cassam notes, if
this really is a coherent possibility, then there is no logical necessity about immunity
to error. But it is not clear why one would expect logical necessity for something
that is ultimately determined by contingent facts about the human body.
The sense of necessity relevant here is nomological necessity (i.e., truth in all possible
worlds with the same laws of nature as this world), and so we will have to
demonstrate that any proposed counterexample to the modal claim is nomologically
possible rather than merely logically possible. But how is one to decide
whether being hooked up to somebody else’s body so as to feel their sensations
really is nomologically possible? How would one convince those who are sure
that it is not? In any case, though, and this is the second point, it is far from clear
that the modal claim really is so important. If Armstrong-type scenarios are indeed
nomologically possible, and were it ever to come about that they are more
common than the sort of somatic proprioception under consideration, in which
there is de facto only one object of awareness, then clearly we would need to
develop both a new theory of somatic proprioception and a new theory of selfawareness.
But there seems little reason why that should influence how we decide
the question of whether somatic proprioception, in the form that we are familiar
with, can be a form of self-awareness, also in the form that we are familiar with.
Let me weaken the claim about immunity to accommodate Armstrong-style scenarios
as follows: necessarily, in a body with unsupplemented somatic proprioceptive
information systems, there is only one object of somatic proprioception,
which is the body itself. This is quite enough to be getting on with.
13. Something like this conflation appears in Evans 1982, 237.
14. Let me stress, though, that my way of spelling out this connection is rather
different from Shoemaker’s or Evans’s. See n. 16 below.
15. The only counter to this would be via the claim that psychological properties
somehow manifest themselves to introspection in an explicitly first-person way,
so that it is impossible to introspect in the manner that (3) attempts to capture.
Something like this view is defended in Chisholm 1969.
16. This is a good place to distinguish my use of the notion of immunity to error
through misidentification as a criterion of self-awareness from Evans’s. Evans
treats the first-person pronoun on the model of a perceptual demonstrative. He
tries to show that demonstrative self-reference achieved with ‘I’ depends on epistemological
links with one’s embodied self that are comparable to the perceptual
links that make possible demonstrative reference to perceived objects. The