Consciousness

• seCtIon tWo: tHe BRAIn

are in consciousness, while others are not – the assumption which is, according to

Dennett, at the heart of Cartesian materialism.

On the second point, Baars clearly distinguishes between conscious and uncon-

scious events, the difference being whether they are in or out of the GW.

To tackle the even trickier problem of subjectivity it may be useful to consider a

related theory, the ‘neuronal global workspace’ model proposed by French neu-

roscientist Stanislas Dehaene and his colleagues (Dehaene et al., 2006; Dehaene,

2014). The immediate advantage of this version of the GW idea is that no process

or information has to ‘become conscious’ or ‘enter consciousness’. In this version,

a collection of specialised unconscious processors compete for access to the

limited-capacity global workspace, which is probably dependent on long-range

circuits involving the prefrontal cortex, anterior cingulate, and connecting areas

(Dehaene and Naccache, 2001). Information can then be widely broadcast to

other brain areas, and ‘This brain-scale broadcasting creates a global availability

that results in the possibility of verbal or non-verbal report and is experienced as

a conscious state’ (Dehaene, 2009, p. 468).

The crunch here comes with the word ‘and’, which can be interpreted in two com-

pletely different ways. One implies an and then: when information gets into the

GW, something else very special happens  – and then it ‘becomes conscious’ or

‘enters consciousness’. If this is the interpretation you favour, then the transforma-

tion is magic – or at least completely unexplained. Neuronal GWT cannot account

for subjectivity or deal with the hard problem.

The other interpretation is that the ‘and’ equates the two. That is, being accessible

to report simply is what we mean by being conscious: subjectivity and access are

the same, and there is no hard problem to solve. This is the interpretation that

Dennett urges upon us; for him, the hardest part of understanding the neuronal

GW thesis correctly is acknowledging that global availability does not cause some

‘brain-scale

broadcasting creates

a global availability

that results in the

possibility of verbal

or non-verbal report

and is experienced as a

conscious state’

(Dehaene, 2009, p. 468)

T1 versus T3: unmasked or masked stimuli

(both attended)

T2 versus T3: unmasked versus masked stimuli

(both unattended)

T1 versus T2: accessed versus non-accessed stimuli

Seen stimuli (T1) > missed (T2) during the attentional blink

Unmasked words (T1) Masked words (T3)

Unmasked words (T2)

>

masked words (T3)

(both used as unattended

primes)

T1

Conscious

high strength

and attention

T2

Preconscious

high strength,

no attention

T3

Subliminal

weak strength

Global

workspace

FIGURE 5.7 • (Left) Dehaene and colleagues’ scheme for showing two ways in which stimuli can fail to gain access to the global

neuronal workspace. (Right) Reinterpretation of neuroimaging experiments in this framework (after Dehaene et al.,

2006).