integrated information theory - uzh

Integrated InformationTheory

Phenomenal experience, mathematically formalised

John Smallridge

What does IIT say?

Consciousness is a special type of ‘information’

Information can be calculated

But, what is ‘information’?

The birth of a theory

The classical approach:

Describing matter in enough detail will explain why it feels at all

The hard problem:

Abstractions only produce more abstractions


The classical approach:

Describe phenomena using the language of matter

The alternative?

Describe matter using the language of phenomena


Let’s talk about how consciousness feels …

and then think about what kind of physics would support it …

instead of the (classical) reverse approach


For a theory, we first need ‘axioms’

These are statements we hold to be true

If we make some useful axioms about consciousness,

…maybe we can derive everything else

The birth of IIT

What does Integrated-Information Theory have as its axioms?

The birth of IIT


Existence - ‘‘I experience therefore I am’’.

The birth of IIT


Existence

Composition - Left, right, red, blue, triangle, square,

and a red triangle on the left.

The birth of IIT


Existence

Composition

Information - Each experience differs from other possible experiences. It is this because it is not everything else

The birth of IIT


Existence

Composition

Information

Integration - An experience is more than the sum of its parts. A word is experienced as a whole, not as it’s parts.

The birth of IIT


Existence

Composition

Information

Integration

Exclusion - Each experience excludes all others;

It has a spatiotemporal resolution.

The birth of IIT


Existence

Composition

Information

Integration

Exclusion

From truths to guesses

These axioms don’t offer anything for our mainstream concepts about matter and causality … yet

We need to derive ‘postulates’ from them to link them to a physicalist world-view

The postulates of IIT

What must a physical system satisfy to generate experience?

Existence - Mechanisms exist. System = a set of mechanisms



Existence

Composition - Mechanisms can be combined



Existence

Composition

Information - A mechanism can contribute to consciousness ifit constrains past and future states of the system



Existence

Composition

Information

Integration - A mechanism can contribute to consciousness ifit is irreducible to the info of its components



Existence

Composition

Information

Integration

Exclusion - In a system, there is only one conscious set of mechanisms. Why? Analytical reasons.



Existence

Composition

Information

Integration

Exclusion

A short note on ontology

Okay, we’ve found a way to describe conscious physical systems using a language of phenomena

But, it has subtext: Consciousness is identical to physical properties

How is IIT used?

If I want to assess the consciousness of a system, what does IIT give me as an output?

How is IIT used?

If I want to assess the consciousness of a system, what does IIT give me as an output?

Answer: A graph, and a number.

Wait, what?

How is IIT used?

Example:

I take 3 logic gates from a computer and connect them together

Gates active for specific inputs:

AND = 1,1OR = 1,0 / 0,1 / 1,1

XOR = 1,0 / 0,1

How is IIT used?

IIT then breaks this toy system into its components

and stimulates them to define

the cause-effect structure of

the system as a whole

How is IIT used?

Cause-effect structure?

This is a statistical description of the system

It uses high-dimensional statistics to answer:

Given the current state, how certain can I be about the states which led to this moment, and the states which are going to happen?

How is IIT used?

What does this mean for the system’s conscious experience?

If the cause-effect structure of the system is more thanthe sum of its parts, and constrains itself

dynamically, it exists from its own intrinsic perspective

The cause-effect structure, according to IIT, is identical to the

experience being had by that system

How is IIT used?

The cause-effect structure, according to IIT, is identical to the

experience being had by that system

Which ‘qualia’ are present, and ‘how much’ do they exist?

How is IIT used?

But there’s more:

We can now look for the constellation of qualia which is maximally irreducible – a set of qualia which are the most real from the system’s own perspective.

How is IIT used?

But there’s more:

We can now look for the constellation of qualia which is maximally irreducible – a set of qualia which are the most real from the system’s own perspective.

The value of that maximum irreducibility is called Phi (Φ)

Φ tells us how conscious the system is

How do we calculate Φ?

In this lecture, we won’t

But here’s where you can try for yourself:

Demo: http://integratedinformationtheory.org/calculate.html

And I’ll put extra slides on the course website:

http://integratedinformationtheory.org/calculate.html

What do you think of IIT?

Does this theory sound useful to you?

Does it tackle the ‘hard problem’ of consciousness?

What does IIT predict?

IIT has some interesting consequences

- Consciousness is lost due to a loss of integrated-information

- Feedforward neural networks have no conscious experiences (e.g. computer vision, and the cerebellum)

- Some non-biological devices have small Φ values (e.g. photodiodes)

- Some systems potentially contain multiple conscious entities (e.g. split-brain patients)

Problems with IIT

IIT has many supporters, but also several critics:

Problems with IIT

IIT has many supporters, but also several critics

What is wanted is a new way to think about consciousness in research

IIT is agreed to be a great starting point …

but by no means a satisfying solution

Is IIT practically useful?

We cannot manipulate a whole brain to calculate Φ(neither physically nor computationally)

But we can use the theory to make ‘approximations’

Bedside diagnosis

What do you do when you have a patient in hospital who is unresponsive to stimuli, and yet may be conscious?

“Is it locked-in syndrome?”

“They took too much ketamine at a party?”

“Is the patient successfully anaesthetised?”

Bedside diagnosis

The Perturbational Complexity Index (PCI)

Inspired by the ‘Information’ and ‘Integration’ postulates, a measurement procedure was designed

Time (milliseconds)

Time (milliseconds)

Time (milliseconds)

Sarasso et al., 2014

Bedside diagnosis

The Perturbational Complexity Index (PCI)

A combination of Transcranial Magnetic Stimulation (TMS), Electroencephalography (EEG), and classical Information Theory

Bedside diagnosis

What does this all mean?

Integrated-Information Theory is currently the most clearly defined theory of consciousness

It is currently called IIT 3.0 because it is an evolving concept

It is creating fresh debates, novel ideas, meaningful experiments, and extra lectures to teach.

Final thoughts: Is describing the same as understanding?When Louis Armstrong was asked

“What is Jazz?”

He replied

“Man, if you gotta ask, you'll never know.“

We could say the same about attempts to understand consciousness

Further reading

∞ Oizumi, Albantakis, Tononi, 2014 - From the Phenomenology to the Mechanisms of Consciousness: Integrated Information Theory 3.0

∞ Tononi et al., 2016 - Integrated information theory: from consciousness to its physical substrate

∞ Integrated-Information Calculator - integratedinformationtheory.org/calculate.html

∞ Internet Encyclopedia of Philosophy on IIT - iep.utm.edu/int-info/

∞ Herzog et al., 2019 - The unfolding argument: Why IIT and other causal structure theories cannot explain consciousness

∞ Mindt, 2016 - The Problem with the ‘Information’ in Integrated Information Theory

∞ Casali et al., 2013 - A Theoretically Based Index of Consciousness Independent of Sensory Processing and Behavior

∞ Sarasso et al., 2014 - Quantifying Cortical EEG Responses to TMS in (Un)consciousness

http://integratedinformationtheory.org/calculate.html

https://www.iep.utm.edu/int-info/

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