IIT Lecture

Last but not least:
Giulio Tononi “Consciousness as Integrated
Information”

2004
IIT is still being
developed
early versions
similar to NRT
2019
more recent
versions are
more distinctive
and ambitious

A convert: Christof Koch

Inside the Tononi lab

Madison Wisconsin (not Washington)

IIT: basic claims summarized
consciousness is a basic irreducible ingredient of
physical world
quantity of consciousness correlated with amount
of integrated information in a system
‘integrated information’ (= phi) defined in terms of
additional info generated by a complex that isn’t in
the constituent parts
quality of experience determined by informational
and causal relationships

Route: a ‘top down’ approach
we don’t know
enough about brains
to start there
we do know the basic
characteristics of our
consciousness
so we try to specify what
a physical system would
have to be like to
produce such
characteristics

in more recent versions
IIT starts with 5 ‘axioms’
about the general
character of experience
then infers 5 ‘postulates’
specifying properties the
physical substrate of
consciousness must
possess given the axioms

IITs Five ‘axioms’
(1) Existence (2) Composition
(3) Information (4) Integration
(5) Exclusion

Axiom 1
Existence:
consciousness exists
intrinsically
I know my experience exists from its own
perspective independently of any external
observer

Axiom 2
Composition: experience
is structured, possess
multiple parts & aspects
a typical human experience
is very complex – can be
divided into parts and
properties in many ways

Axiom 3
Information: my current
consciousness has a specific
character
it differs in specific ways
from all the many other
combinations of
experiences I could be
having

Axiom 4
Integration:
consciousness is
unified, is is irreducible
to its constituent
experiences considered
separately

Axiom 5
Exclusion:
consciousness is definite in
content and spatio-temporal
grain – it flows at a certain
speed, and has a certain
resolution (finite)

IIT starting point: the integration
axiom
how do they
differ?

humble photo diode
simple electronic device
capable of detecting light
if no light, no current
if there’s light in front it
emits a current from the
back

compare diode with digital
camera sensor
very basic 1 megapixel
sensor
creates digital image
with 1 million individual
pixels

today bigger sensors are commonplace:

in one sense the sensor is as
powerful as your visual system
capable of registering huge
number of totally different
and complex visual scenes

so a greater quantity of information
than the diode
But the camera doesn’t
integrate its
information
It doesn’t have a high
PHI

the image stored in camera (or shown on screen)
is very different from your experience of it

Why?
image on screen
consists of nothing but
large number of pixels
next to one another in
space
each individual pixel is
an entirely separate
entity

slicing sensor into individual pieces
changes nothing
each sensor operates
in isolation
the information it
generates is
independent of the
information others
generate
typical of low-phi
systems

very low phi
the information carried by
the whole is no greater
than the individual parts
the whole is fully
reducible to the parts
such systems not
highly integrated
informationally

whereas …
your experience of
a picture is deeply
unified/integrated
each part is
experienced with
every other part
to make a single
unified visual state

your auditory experience is unified
too …
sound of
voice
sound of bell
heard together: in single
unified auditory experience

bodily experience too ….
head feelings +
leg feelings +
hand feelings +
back feelings
all felt together as
parts of unified
phenomenal bodyimage

our consciousness as a whole forms
a unified whole:

‘what’s THE most distinctive and
remarkable feature of consciousness?’
= not an
implausible
answer!

IIT takes unity as a guide to locating
consciousness in physical world
identity! (according to IIT)
deeply unified
experiential
state
state of physical
system that’s
deeply integrated
physically

a distinguishing feature of ITT
the idea that integration is
necessary for an experience
to exist is not controversial
for IIT unity/integration is
sufficient – it’s all that’s
required

so: unity is important, what next?
Integration:
postulate
information is integrated if it
cannot be reduced to the
information produced by its
parts separately
sounds reasonable, what
does it amount to in
practice?

another novel feature of IIT
IITs account of
irreducibility
yields precise
mathematical
framework for
quantifying integration

quantifying ψ: basic idea
C
A
B
suppose we have a system
of simple units that carry
some information, but we
want to test whether it’s
integrated
there’s a simple procedure
we can carry out
System S

testing irreducibility
A
suppose we divide
the system S into
these two parts
C
S1
B
S2
if the total information
of S1 + S2 is the
same S, then S is
reducible, and it
doesn’t possess
integrated information

ψ = quantity of integrated information
C
A
B
now consider all the ways of
dividing the system S into two
parts
find the part P which has the
closest amount of information to S
itself
the difference between P and S
reveals the extent to which S is
more than the sum of its parts –
hence the degree of phi

in practice ...
phi calculable for simple
networks of artificial
neurons
rapidly becomes
incalculable for more
complex systems
can only be estimated
for brains

IIT’s prediction
moderate PHI
brain-like systems differ in
complexity – differ in
quantity of PHI
higher PHI means greater
quantity of consciousness
very high PHI

Information itself: what is it?
a key issue, IIT’s account
is evolving
their aim: to provide
completely
objective/intrinsic
account of information

initial idea: information linked to
reduction in uncertainty
2 possible states; when outcome
becomes known there’s a small
reduction in uncertainty
6 possible states, when outcome
becomes known, greater
reduction in uncertainty – more
information produced

analogously:
typical human brain capable of
producing a HUGE number of
different experiences at any one
time
when the visual house-experience
is produced (rather than one of
the many alternatives) there’s a
huge reduction in uncertainty –
and a significant amount of
information is created

more recently: causality plays more
prominent role
A
a system has “causally
effective information” (CEI) if
can causally influence
influence itself, at and over
time
C
B
a way of construing the
axiom “consciousness exists
intrinsically”

more generally: a brain-like system
will have huge amount of CEI
many ways it’s current
state rules out previous
states
it’s possible to measure
CEI for simple systems
of units – not brains
many ways it’s current
state constrains
subsequent states

Maximality & Exclusion Postulates
your brain has a huge phi – it’s
immensely integrated
it will contain sub-systems
which are also integrated, and
have significant – but lower -
phi
are these sub-systems also
conscious?

Not according to IIT:
to be conscious a state of a
system S must have
maximal phi
parts of S with smaller phi
won’t have maximal phi, and
so won’t be conscious

Intriguing consequence of Exclusion
suppose you link your brain
to a bigger system – e.g. an
integrated internet
if the larger system has
larger phi than your brain,
you’d cease to be
conscious

Summing up so far:
IIT tells us where to find
consciousness in physical
systems – look for
maxima of integrated
information
But this isn’t the
whole story

IIT, NRF and causation
Chalmers’ non-reductive
functionalism is
epiphenomenalist
all real causal power is at
the base-level of physical
particles

IIT rejects epiphenomenalism
systems with hi phi have
genuine causal powers
(they claim)
able to induce changes in
systems of low-level
particles/fields

From quantity to quality
IIT also offers an account of
why a particular experience
has the particular distinctive
quality it does
“… how integrated information is generated within a
complex determines not only the amount of
consciousness it has, but also what kind of
consciousness”

the most ambitious – and challenging -
aspect of IIT
a brain will have many overlapping causeeffect
structures that integrate information
in principle these can all be
fully described in a single
many-dimensional diagram: a
“cause-effect space”

causal profile generates “conceptual structures” of
interrelated elements – can be represented by highdimensional
spaces

a key identity:
an experience is identical with a
maximally irreducible conceptual
structure (MICS)
the “concept” included in such a
structure are themselves
irreducible causal sub-systems
with high phi (small)

What does the identity really
amount to for IIT?
causal structure
whose inner nature
is experiential
an abstract
mathematical object?
(NO)
or a physical/causal
process in real world?
(YES)
physical system
(neurons)

IIT a variety of functionalism?
YES
phenomenal character of an
experience is being determined
by causal properties
NO
experience isn’t eliminated in
favour of causal properties
phenomenal properties are real
and irreducible and exist in
causal structures/processes

further predictions: is the internet
conscious?
NO: vast amount of
information, but not
deeply integrated …
so low phi and low (or
zero) consciousness

ordinary computers – not capable of
consciousness
feed-forward
circuit design
entails low phi
lack feedback
loops – unlike
brains

But: variable realizability
neuron
replacement
process preserves
causal
connections – so
consciousness
maintained

panpsychism?
Tononi confines
consciousness
to systems with
some
computational
complexity
Tononi
Koch happy to
see it
everywhere
(e.g. in atoms)

scientific evidence for IIT
Tononi claims IIT is
empirically supported by
findings from neuroscience

cerebellum versus cortex
cortex
cerebellum has 70 billion
neurons, the thalamo-cortex
only 16 billion (approx)
damage to the cortex has
devastating effects on
consciousness, often obliterating
it
removing someone’s
cerebellum has no effect
on their consciousness –
why?
cerebellum

IIT can explain: big differences in
neural connectivity
cerebellum – low lateral
connectivity, lots of
isolated neural
subsystems operating in
parallel – LOW PHI
cortex: neurons in different
areas highly integrated –
connections between
different parts across large
and small regions –– HIGH
PHI

also: divided brains
dividing cortex by
cutting corpus
callosum produces
two separate centres
of consciousness
result compatible with
IIT: each resulting
half-cortex still has
massive phi, so
should be conscious

human brain: IIT predictions
normal waking brain:
neurons VERY
interconnected: very high phi
non-dreaming sleeping brain
(non-REM): low phi, low
interconnectedness

testing the predictions: transcranial
magnetic pulse (TMP)
stimulate neurons in the
cortex
use EEG to track what kind
of ‘echo’ we get
a long-lived complex one
suggests massive causal
interconnections

Tononi & Massimi experiment

results vindicate IIT
EEG reveals large “ring”
reverberating across cortex
when conscious brains hit by
TMP
BUT only a small
local echo when
deeply unconscious
brains
also a large ring
for dreaming
brains subjected
to TMP
Koch https://alleninstitute.org/media/filer_public/1e/a2/1ea26ff9-8fba-4663-be30-
d33a153ebc6b/2013_03_aconsciousnessmeter.pdf

hope of reliable ’consciousness meter”
IIT’s technique can distinguish
vegetative (very low phi) from
minimally conscious states
(higher phi)

Is everyone happy?
(of course not!)

John Seale isn’t impressed
‘information’ doesn’t exist in
reality, it’s observer/subject
relative – so we can’t explain
conscious subjects in terms
of information!
IIT also leads to panpsychism,
which is just absurd!!

Searle is wrong:
as we saw earlier, IIT offers an
intrinsic causal account of
‘effective information’
the account is still being
developed, but it’s not
observer-dependent

Scott Aaronson’s critique – in
2014 blog post
computer scientist
expert in complexity
theory and quantum
computing
Why I Am Not An Integrated
Information Theorist (or, The
Unconscious Expander)

counterexample:
some very simple 2-d
electronic networks –
Vandermonde system,
expander graphs – can
have very high phi
expander graph
but not intuitively
plausible to think
they’re conscious

Tononi unperturbed:
“Scott Should Stare at
a Blank Wall and
Reconsider”
lots of reasons for
thinking such systems
WOULD be conscious
http://www.scottaaronson.com/tononi.docx

one possibility: a 2-d expanse of
experienced colour
though in fact, experience of empty space is not simple at
all – lots of distances and relations present in experience

some are sceptical
why think a given
location in cause-effect
space HAS to
correspond with a
particular phenomenal
property?
inverted spectrum-type worry

also this worry:
why think a given
location in cause-effect
space HAS to give rise
to ANY phenomenal
property at all?
absent qualia/zombie type worry

IIT response:
cause-effect space is
massively complex
if we understand it
better the relationship
between conceptual
structure and
experience may no
longer be puzzling

end

Panpsychism
Hard problem has
an easy solution …
Everything in the
universe conscious!
Nothing special
about brains

Panpsychism
Prominent Recent advocates:
- Thomas Nagel ‘Panpsychism’ (Mortal Questions)
- Galen Strawson ‘Realistic Monism’ (Journal of
Consciousness Studies, 2006)
- Philip Goff Consciousness and Fundamental
Reality, OUP
2017http://www.philipgoffphilosophy.com/publica
tions.html

Sounds dippy (or mad)
What will the nail feel?

But …
In fact there are
impressive arguments
for the doctrine!
Incompleteness
of Physics &
Inscrutability of
Matter
Argument from
Emergence

To start: argument from physics
Dates back to Bergson,
James, Russell at start
of 20 th century
Bertrand Russell
(1872-1920)
In recent years often
linked to
“Russellian Monism”

Inscrutability Argument 1
According to physics the basic properties of
matter are mass, impenetrability, charge,
size, force, etc.
All these properties are causal or structural
They do not specify the intrinsic nature of
what has the causal/structural properties.

Inscrutability Illustrated
Particle Interactions: intrinsic natures unspecified

Inscrutability Illustrated
Particle Interactions: intrinsic natures SPECIFIED (a)

Inscrutability Illustrated
Particle Interactions: intrinsic natures specified (b)

Inscrutability Argument 2:
At least some basic physical
particles must possess some
intrinsic nature
A world where all particles
consist of nothing but regions
of causal potentiality to affect
other regions of causal
potentiality isn’t a world
elementary particles

Result: argument to a new form of the
identity theory
Some forms of matter have intrinsic natures
We know experiences have intrinsic natures
We know experiences and brains are closely linked
So: perhaps the intrinsic nature of conscious
states are the intrinsic nature of certain brain
states
So: experience reveals the intrinsic nature of
certain portions of the physical world: human
brains

Obvious hurdles?
At least one: the ‘grain problem’:
A visual
experience
(smooth)
Part of brain -
magnified
(grainy)

there’s a structural mismatch between the
smoothness of experience and the courseness
of physical objects such as brains
A visual
experience
(smooth)
Part of brain -
magnified
(grainy)

But again there other options …
Maybe consciousness exists
NOT in individual particles but a
smooth field generated by these
particles
Maybe consciousness exists
within the fabric of spacetime
itself – and is triggered by
neural activity by brain particles

Next: the emergence argument for
Panpsychism:
Experience = real and irreducible
Experience = physical in nature
Experience = non-emergent
So: experience must be present in physical
ultimates (atoms etc.)

Emergent physical properties: our
earlier example

wing-property = emergent
Just a matter of
arranging
ordinary atoms in the
right ways
No new basic
physical properties
needed

Phenomenal properties = not emergent (in
that way)
huge, baffling, gap
main lesson of recent
philosophy
of mind
experience

hence panpsychism
(1) experience
exists here
(3) experience must
exist here too!
‘I’m composed of
nothing but atoms’
(2) experience doesn’t
emerge en route

Objection:
Maybe some physical things
are conscious, but
others aren’t!

Nagel’s response: matter is fungible
You can
build a
person from
the particles
in a fridge
so the fridge’s
components
must be
conscious too

fungibility
money is fungible: pounds can be
converted into dollars, euros – and
vice versa
according to physics mass-energy
is fungible as well: particles can
turn into energy and vice-versa, any
kind of particle can be turned into
any other particle

so:
all physical
objects are
build from the
same basic
building blocks
if electrons in
brains are
conscious, all
electrons will be
conscious
i.e. elementary
particles such as
quarks, electrons etc.

Objection:
I wonder if there’s anything
that it’s like to
be human?
How can an elementary particle have
mentality?

Response : atoms = simple minds
humnnnnnnnnnnnn, buzzzzzz…

Varieties of Panpsychism 1
Weak Panpsychism: every material thing has
experiential AND non-experiential properties
Strong/Pure Panpsychism: every material thing
has ONLY experiential properties

Weak Panpsychism: schizophrenic matter
material object
experiential
Problem of ‘how brains
acquire experience’
is solved
non-experiential
= single kind of stuff
Interaction problem
remains …

Strong Panpsychism: a form of idealism
but different from
Berkeley’s
Physical space exists and is
filled with physical objects –
these have an experiential
nature

Further variants of panpsychism
SMALLIST
the universe is
composed of elementary
particles and/or fields
each fundamental
constituent is a separate
subject of experience or
centre of consciousness
COSMIC
the universe consist of a
single all-encompassing
subject or state of
consciousness

Issues and problems
smallist
cosmic
how can small subjects
combine to form
complex states of
consciousness
why we seem to be
separate subjects if
in reality we’re all
the same subject?
= COMBINATION
PROBLEM
= DE-COMBINATION
PROBLEM

Let’s take a closer look:
the
‘combination problem’?
= long-standing problem for panpsychists

William James’ influential
formulation
Take a sentence of a dozen words,
and take twelve men and tell to
each one word. Then stand the men
in a row or jam them in a bunch, and
let each think of his word as intently
as he will; nowhere will there be a
consciousness of the whole
sentence.
Principles of Psychology
1895

Combination problem: minds/subjects
one big MIND/SUBJECT
zillions of little MINDS
(OR SUBJECTS)
How do the little constitute the big
without losing or changing their
character? (And so ceasing to exist?)

Combination problem: experiences
one big experience
zillions of little
EXPERIENCES
How do the little constitute the big without
losing or changing their character? (And so
ceasing to exist?)

“subjects” pose the more serious
problem
if we think of them as akin to Cartesian souls:
entirely discrete, self-contained substances –
how can these blend to make a further
subject?

experiences liberated from subject-captivity
might be more akin to liquid
mercury
combination not
obviously
problematic
able to fuse or merge or divide

so …
perhaps the physical
world IS composed of
vast numbers of
partially over-lapping
micro-experiences!

a problem remains:
how do the microconstituents
of brains
produce complex unified
human-type
experiences?
not as big a mystery as
physicalism faces (or so
panpsychists can say)

Conclusion:
Still mysterious
But perhaps not QUITE
as hopelessly mysterious
as McGinn claims.

moving on …

quantum pioneers – 1905 - 1930
Albert Einstein
Erwin Schrodinger
Werner Heisenberg
Niels Bohr
John von
Neumann
Niels Bohr

quantum theory …
our best theory of the
atomic world
what’s its relevance to
consciousness?

consciousness and quantum theory: many
have argued there is a connection
several proposals in
the literature
there’s an intriguing route
to dualism that’s fairly
easy to understand
but much hangs on the
interpretation of QM -
remains very controversial

an example of quantum weirdness: two
slit experiment

What happens when small objects pass
through a hole in a solid wall?
many will
bounce off
a few will get
through
clustering behind
the holes
many will
bounce off

If light consists of rays of tiny particles – as Newton
thought - then the same pattern should be produced
light source
a few will get
through
clustering behind
the holes

what happens when water-waves pass
through two slits
an interference pattern is created, a
sequence of peaks and troughs – very
unlike the particles!

water-waves passing through
two holes
interference pattern

1801 Thomas Young’s experiment –
refuting Newton
interference pattern
formed – light doesn’t
collect behind the two
holes – light a wave,
not a collection of
particles

quantum case 1: electrons
one hole blocked,
electrons behave
like particles,
clustering behind
hole

quantum case 2
when two slips are
open, the
electrons behave
like waves – an
interference
pattern forms

quantum case 3
what if the electrons are
fired one by one, rather
than in a great number
simultaneously?
bizarrely an
interference pattern is
still formed – but
gradually, over time

quantum case – real photos
a gradually forming interference
pattern

quantum case 4:
suppose a measuring
device is installed –
capable of registering
when an electron
passes through a slit
detector
interference pattern
immediately
vanishes!

Lessons?
wave-particle
duality
there’s a wave-like
character to all forms of
matter
importance of
observers &
measurements
quantum systems behave
differently depending on
whether they are
observed or not

“interpretations of quantum theory”
there’s the
mathematical
framework – which isn’t
controversial, it works
brilliantly
different interpretations
tell very different stories
there’s the issue of what
reality can be like given
the maths

orthodox interpretation – von
Neumann & Bohr
systems evolve according to the
fully deterministic Schrodinger
wave equation – this allows you
to predict the exact state of a
physical system at some later
time, if you know it’s earlier state
collapse postulate: assigns
probabilities to how we’ll find a
state at a later time if we
measure it

Schrodinger equation: describes
possibilities/probabilities
different ways the
system might be
quantum
system
at different places
and times
different probabilities
assigned
“superposition”

then a measurement takes place
quantum
system
definite outcome
registered (e.g.
particle is at
specific location)
and wave function “collapses”,
superposition ceases

prior to measurement
superposition
different ways the
system might be
quantum
system
at different places
and times
different probabilities
assigned
no fact of the matter
as to the condition of
the system

notorious quantum paradox –
featuring a cat & a sealed
box

cat locked in chamber for an hour
50% chance radiation will be emitted, triggering cyanide

before anyone looks there’s
no fact of the matter about
the cat’s fate
there’s a superposition of a
living cat and a dead cat

then someone opens the box
and happily
the cat is
alive!

big issue: what kind of thing is a
measurement?

von Neumann-Wigner: measurement
essentially involves consciousness
conscious perception
produces collapse

Wigner: consciousness can’t be physical
Until not many years ago, the
‘existence’ of a mind or soul would
have been passionately denied by
most physical scientists. . . . There are
[however] several reasons for the
return, on the part of most physical
scientists, to the Spirit of Descartes’
‘Cogito ergo sum’ . . . it was not
possible to formulate the laws of
quantum mechanics in a consistent
way without reference to
consciousness.

problem 1: Wigner’s friend
Wigner’s friend makes
observation of
quantum outcome at
1pm
At later time 2pm
Wigner asks friend
what she saw

For Wigner the wave
function for the whole
system collapses when
he gets the answer from
friend at 2pm
For the friend the wave
function collapses when
she makes the
observation at 1pm
To avoid paradox:
conscious perception
collapses wave function
– this initially occurs at
1pm when friend sees
result

problem 2: confining superpositions
measuring system =
ordinary physical device
let’s suppose the camera
is ‘observing’ the cat
single quantum system/state
where’s the
problem?

the problem:
measuring system =
ordinary physical device
measuring device will
itself exists in a
superposition
result: a photo of dead
cat + photo of live cat
single quantum system/state

the problem is hard to cure:
in a superposition
another physical
measuring device
the new device will enter
a superposition as well
single quantum system/state
we’ll still get a photo of
dead cat + photo of live
cat

ending the regress: a non-physical
observation collapses wave function
immaterial observer
single quantum system/state
no superposition – quantum
rules don’t extent to nonphysical
things

so: quantum theory provides one
route to dualism
the observers which collapse
wave functions are nonphysical
these immaterial minds are
not epiphenomenal: they have
a big impact on the material
universe

however, there are complications
this route to dualism depends on
the orthodox interpretation of
quantum mechanics
there are alternatives which don’t
involve the collapse of the wave
function at all
there are alternatives where
wave function collapse doesn’t
require non-physical intervention
Bohr/Heisenberg

no collapse: many worlds
nothing every collapses the wave equation - all
possible outcomes of any quantum system
become actual

no collapse: many worlds
Schrodinger’s cat
alive and dead –
in different
branches of the
universe
everyone’s life has a
similar massively
branched structure

GRW interpretation
thanks to a
probabilistic law
wave function
collapses
spontaneously
quantum
system
QM equations modified to as to allow a tiny
probability of collapse in the absence of any
interaction with measuring device

quantum realm as mysterious as
consciousness
quantum theory works, but
how it should be
interpreted remains supercontroversial!

Consciousness
The End