Consciousness

• seCtIon tWo: tHe BRAIn
  stationary red light because consciousness was delayed until all
  the relevant information was in, and only then was it allowed ‘into
  consciousness’.
  Dennett investigates many such phenomena and asks how we
  might distinguish between these two views. Surely one must be
  right and the other wrong? Surely we must be able to say, at any
  point in time, what was actually in that person’s stream of con-
  sciousness, mustn’t we? No, says Dennett, because there is no way,
  in principle, of distinguishing these two interpretations. He illus-
  trates this by comparing two fanciful interpretations, the Orwellian
  versus the Stalinesque revision (Concept 6.2). Ultimately, ‘This is a
  difference that makes no difference’ (Dennett, 1991, p. 125). If we
  think one or other must be true, we are still locked in the Cartesian
  Theatre.

How then can we understand these odd phenomena? When things seem mys-

terious, it is often because we are starting with false assumptions. Perhaps we

need to look again at the very natural assumption that when we are conscious of

something there is a time at which that conscious experience happens.

It may seem odd to question this, but the value of these oddities may lie precisely

in forcing us to do so. The problem does not lie with timing neural events in the

brain, which can, in principle, be done. Nor does it lie with the

judgements we make about the order in which things happen.

It begins when we ask ‘But when does the experience itself hap-

pen?’ Is it when the light flashes? Obviously not, because the

light hasn’t even reached the eye yet. Is it when neural activ-

ity reaches the lateral geniculate? Or the superior colliculus?

Or V1, or V4? If so, which and why, and if not, then what? Is

it when activity reaches a special consciousness centre in the

brain (or in the mind)? Or when it activates some particular

cells? Or when a complicated consciousness-inducing process

is carried out?

Almost all the theories we have encountered so far give

answers to these kinds of question. For example, in GWT

things become conscious when they enter the global work-

space and are broadcast, for Zeki consciousness happens

when activity in brain cells becomes explicit, and for Crick

the ‘awareness neurons’ must be active. But any theory of this

kind has to explain how subjective experiences arise from this

particular neuron, or this particular kind of neural activity, at

this particular time.

So perhaps we need to drop yet another intuition  – the idea

that there must be a time at which conscious experiences hap-

pen. Perhaps we in fact create temporal unity retrospectively,

in a kind of very personal storytelling. Our stories include the

order in which things have happened, but only as a reasonable

way to make sense of events, not because any ‘actual conscious

experiences’ also happened in that order.

Reality

Percept FLASH

FLASH

FIGURE 6.15 • The flash-lag illusion. When a flash
and a moving object are shown in
the same position they appear to
be displaced from each other. In
this version the flash appears to lag
behind the moving ring.

ACtIVItY 6.3

The cutaneous rabbit

The cutaneous rabbit is easy to demonstrate and a

good talking point. You will need a very sharp pencil

or a not-too-dangerous knife point – something with

a tiny contact point but not sharp enough to hurt.

Practise the tapping in advance until you can deliver

the taps with equal force and at equal intervals.

Ideally use a volunteer who has not read about the

phenomenon. Ask the volunteer to hold out one bare arm

horizontally and to look in the opposite direction. Take

your pointed object and, at a steady pace, tap five times

at the wrist, three times near the elbow, and twice on the

upper arm, all at equal intervals. Now ask what it felt like.

If you got the tapping right, it will feel as though light taps

ran quickly up the arm, like a little animal. This suggests

the following questions. Why does the illusion occur?

How does the brain know where to put the second, third,

and fourth taps when the tap on the elbow has not yet

occurred? When was the volunteer conscious of the third

tap? Does Libet’s evidence help us understand the illusion?

What would Orwellian and Stalinesque interpretations be?

Can you think of a way of avoiding both?