Chapter
Six
The unity
and shape or form. In these higher areas, the original mapping
is lost, and features are dealt with regardless of where on the
retina they originally fell.
These different processes take different lengths of time. For
example, colour is processed faster than orientation, and orien-
tation faster than motion. Then there are the two major visual
streams to consider: the dorsal stream controlling the fast action
of catching the coin deftly (if you did), and the ventral stream
involved in the more time-consuming process of perceiving
the coin as a coin, with the two in complex dynamic interaction
with each other. There is no single place and time in the brain at
which everything comes together for the falling coin to be con-
sciously perceived as one thing rather than a floating collection
of attributes. How, then, do we consciously perceive a falling
coin as one moving object?
The problem described here is that of visual binding, but the
more general ‘binding problem’ applies across many different
sensory modalities, and at many levels of description, from the
neural level to the phenomenological (Bayne and Chalmers, 2003). Some of these
levels (most obviously the neural processes) can be studied quite separately
from consciousness (Revonsuo, 1999, 2009). Towards the more cognitive end, the
problem is how conjunctions of features are represented, ranging from the bind-
ing of shape and colour in detecting blue triangles or red squares, to the binding
of words and phrases with their roles in sentences. In particular, the problem for
consciousness is how this kind of binding happens dynamically in real time. As
the coin flips, what keeps the colour, form, movement, and other attributes of the
coin together?
This problem is intimately bound up with both memory and attention. For exam-
ple, try remembering entering your own front door. To do this successfully, various
features have to be imagined at once: maybe the colour of the door, the flowers
growing round it, or the pile of rubbish in the corner, probably the key on its ring
and the way you have to turn it. We considered in Chapter 3 the question of just
how detailed this experience really is; if vision does not actually operate by build-
ing up pictures of the world, maybe lots of this information is simply not given.
For example, when I imagine a face, my imaginative experience may not specify
whether or not the person is wearing glasses (Pylyshyn, 2003, p. 34). And when
you imagine your door, the pile of rubbish may be neither present nor explicitly
absent; your imagining may simply not specify. But the concept of binding does
not commit us to any particular position as regards the amount of detail; even
if all we imagine is turning a key in a nondescript door, there are still things that
need binding to each other. And as a result of the binding, you experience a more
or less unified memory of something you do every day. All that information is held
briefly in working memory and, as we have seen, some theories of consciousness,
such as global workspace theories, relate consciousness to working memory, and
to attentional amplification of fronto-parietal circuits.
Some people argue that the binding problem is precisely the same problem as
understanding how attention works – a topic to which we will return in the next
FIGURE 6.1 • Is there a flipping coin somewhere
in the mind or brain? We know
that the colour, motion, and
shape of the coin are processed in
different brain areas, but how are
these features bound together to
produce the single experience of a
flipping coin? The binding problem
cannot be solved by imagining
that they are all brought together
for display to an observer inside
the brain.