BBC Focus 02.2020

INTEGRATED INFORMATION THEORY
Proposed by neuroscientists Giulio Tononi and
Gerald M Edelman, the theory states that the
neural processes that give rise to consciousness
have two key properties. The first is integration.
When you perceive the world, you experience a
single, unified whole that can’t be separated or
broken down into smaller parts. Consider how it’s
not possible to be consciously aware of two
dierent scenes simultaneously. The second key
property is information, which refers to each
conscious experience being highly dierentiated
or informative – you are having this particular
experience rather than an almost infinite number
of others. Critics say that, by arguing that any
system with these two properties gives rise
to consciousness, it is advocating for
‘panpsychism’ – the idea that consciousness is
ubiquitous in the Universe.

GLOBAL WORKSPACE THEORY
Why do we become consciously aware of some
things but not others? This theory, first proposed by
neurobiologist Bernard Baars, likens our thought
processes to a theatre, with most activity going on
behind the scenes. When information arrives on the
‘stage’ or global workspace, it suddenly becomes the
focus of our aentional spotlight and enters our
conscious awareness. French neuroscientist Prof
Stanislas Dehaene has since investigated the neural
basis of consciousness of Global Workspace Theory,
expanding it to the Global Neuronal Workspace
Theory. He proposes that if incoming information
has enough salience and we pay enough aention to
it, then neural activity spreads beyond the brain’s
early sensory processing areas, broadcasting to the
associative areas in our frontal cortex and the
parietal lobes – the ‘global workspace’ that allows
sensory information to reach consciousness.

HIGHER ORDER THEORIES

When you look at an apple, your brain forms a

neural representation of the fruit. Neuroscientists

call this a ‘first-order’ representation and those

scholars who endorse so-called ‘higher order’

theories of consciousness, such as the US

neuroscientist Dr Joseph LeDoux, believe that the

first-order representation always occurs at a

non-conscious level. For you to become

consciously aware of the apple, LeDoux and others

propose that there must be some kind of higher

order thought about, or processing of, that initial

perception (or thought or feeling ) for it to reach

your subjective consciousness.

PREDICTIVE CODING THEORIES

Most people are unable to tickle themselves

because the brain automatically anticipates the

expected sensory consequences of its own willed

actions and cancels them out. In fact, prediction is

fundamental to our experience of the world,

allowing us to overcome the sluggishness and

poverty of information arriving via our senses.

Advocates for predictive coding theories, like Prof

Anil Seth at Sussex University, believe this is key to

consciousness – that what we consciously

perceive is oen based on what we expect rather

than what is actually there. Moreover, they see

these predictive processes as important not only

to our subjective perceptual experiences but also

our very sense of self and feelings of ownership

over our bodies.

AT TENTION SCHEMA THEORY

Consciousness is not some magical, ghost-like

property of the brain that needs explaining,

according to this theory. Rather, consciousness is

simply the brain’s way of modelling what it is

currently thinking about and paying aention to.

Moreover, this is fundamental to how the brain

works rather than dependent on higher order

cognitive processes. “The information in the brain

is not necessarily literally accurate,” says Prof

Michael Graziano at Princeton University, who

developed the theory. “The brain constructs

models – bundles of information – to describe

and keep track of things in the world. It models

objects in the outside world, and it models its own

internal states.”

ILLUSIONISM

Aachment Schema Theory is related to

‘illusionism’ proposed by philosopher Dr Keith

Frankish (and related consciousness theories put

forward by the philosophers Daniel Denne and

Patricia Churchland). “I believe that we do not

have phenomenal consciousness,” says Frankish,

“it’s a kind of introspective illusion, which reects

the limited access we have to our own mental

processes. I call this view ‘illusionism’. The real

task is to explain our intuitions about phenomenal

consciousness – why we think we possess it.”

QUANTUM THEORIES

Quantum mechanics is the branch of physics that

seeks to explain the behaviour of subatomic

particles. Studies have thrown up astonishing

results, such as that particles can be in two states

at once and their behaviour seems to change

depending on whether they are being measured or

not (apparently challenging the idea of an

objective reality). In fact, even an intention to

measure them seems to change their behaviour.

Advocates of quantum theories of consciousness,

like British physicist Roger Penrose, believe this

implies consciousness is somehow linked with the

quantum world, and that quantum processes in

the brain could explain consciousness.

RIVAL CONSCIOUSNESS THEORIES