Patrick Haggard

Institute of Cognitive Neuroscience

Neuroscience and conscious free will

Institute of Cognitive Neuroscience

University College London

Collaborators: James Moore, Marcel Brass, Diane Ruge, Dorit Wenke, John Rothwell, Eamonn Walsh, Dick Passingham, Hakwan Lau,

Valerian Chambon, Angela Sirigu, Simone Kuehn, Wolfgang Prinz

Funding: Leverhulme Trust, ESRC, ESF, COST, Fyssen Foundation

Neuroscience and free will

1. Can the experience of conscious intention be studied scientifically?

2. What are its neural correlates?

3. What is its function?

4. Volition and sense of agency

Neuroscience and free will

1. Can the experience of conscious intention be studied scientifically?

2. What are its neural correlates?

3. What is its function?

4. Volition and sense of agency

6 05

1 0

1 5

2 0

2 53 0

3 5

4 0

4 5

5 0

5 5

Libet et al. (1983)

6 05

1 0

1 5

2 0

2 53 0

3 5

4 0

4 5

5 0

5 5

“23”

Libet et al. (1983)

“23”

Brain activity precedes conscious intention

• Readiness potential preceding voluntary action

-206 ms

• W judgement: awareness of intention

Vo

lta

ge

at C

z (

µV

)

Time (s)0Movement Onset

-1

-206 ms

??

|+

Conscious

Intention

Brain

Activity

Body

Movement

Cartesian view

DualismGhost in machine

Brain

Activity

Body

Movement

Neuroscience after Libet

Conscious

Intention

Implications?

• “Conscious free will” is an illusion

• My brain controls my actions• My brain controls my actions

• “I” know about my actions only very late

• Moral responsibility?

Libet experiment: problems

Methodological issues

• Task is difficult

• Instructions are bizarre

Conceptual issues

• Actions are arbitrary, have no value

• Social context is neglected

• “That’s not what we mean by free will!”

Neuroscience and free will

1. Can the experience of conscious intention be studied scientifically?

2. What are its neural correlates?

3. What is its function?

4. Volition and sense of agency

Brain circuits for intention(Lau, Rogers, Haggard, Passingham, Science 2004)

• Judge time of intention – judge time of action

1. Pre-SMA 2. Dorsal 3. 1. Pre-SMA 2. Dorsal

prefrontal

3.

IntraParietal

When did you experience making the action?

Sirigu, Haggard

Nature Neuroscience 2004

When did you experience willing the action?

When did you experience making the action?

Sirigu, Haggard

Nature Neuroscience 2004

When did you experience willing the action?

Functions of conscious intention

1. Control

Conscious intention controls our action

Cortical

stimulation

DualismGhost in machine

2. None (Daniel Dennett, Daniel Wegner)

Conscious intention is just an illusion stimulationConscious intention is just an illusion

Brain

Activity

Sensory

Feedback

Body

Movement

Conscious

Intention

“postdiction”

Neuroscience and free will

1. Can the experience of conscious intention be studied scientifically?

2. What are its neural correlates?

3. What is its function?

4. Volition and sense of agency

Conscious intention from

direct brain stimulation

• Fried et al. (1991): Neurosurgery for epilepsy

• Exploratory stimulation of • Exploratory stimulation of Supplementary Motor Area

• Anticipatory awareness:“I have an urge to move my right arm”

• Actual movement at higher current

Functions of conscious intention

Control

Conscious intention controls our action

Cortical

DualismGhost in machine

None Cortical

stimulation

None

Conscious intention is an illusion

Predictive learning

Conscious intention may enhance prediction and

monitoring of action outcomes

“Do you really want to be responsible for that?”

Brain mechanism for Intentional Inhibition of Action(Brass and Haggard, J Neurosci., 2007)

Instructions:

• “Prepare voluntary keypress actions…

• “On freely-chosen trials, cancel action at last moment”

• "Judge time of intention to move,whether you actually moved or not”

• Compare brain activity for action and inhibition

• Inhibition trials – Action trials aFMC

sig

nal s

tre

ng

th (

me

an

be

ta v

alu

e)

-0,01

0,00

0,01

0,02

Brain mechanism for Intentional Inhibition of Action(Brass and Haggard, J Neurosci., 2007)

• Anterior Fronto-Median Cortex (BA9)

sig

nal s

tre

ng

th (

me

an

be

ta v

alu

e)

-0,06

-0,05

-0,04

-0,03

-0,02

-0,01

veto act toneInhibit Act Tone control

• Expresses decision outcome “Stop: Don’t do it!”

• Anterior to intentional action areas (PreSMA)

Brain

Activity

Body

Movement

Conscious

IntentionExternal

Effect

prediction

Neural

“Veto”

• Conscious experience accompanies our actions • Conscious experience accompanies our actions and action decisions, but does not control them

• Consciousness may provide a marker of brain learning processes: “don’t do this again”

• So, the will can be educated

Actus Reus

+

Mens Rea

+

= Responsibility

Neuroscience and free will

1. Can the experience of conscious intention be studied scientifically?

2. What are its neural correlates?

3. What is its function?

4. Volition and sense of agency

Is responsibility a basic experience generated in the brain?

...or inference based on action-effect matching?

Intention

Effect

Movement

Time

Beep

Intentional BindingHaggard, Clark & Kalogeras, Nature Neuroscience, 2002

Beep

Awareness

of Beep

Time

Action Effect

(Beep)Shifted

Awareness

of Beep

Perceptual Shift

Intentional BindingHaggard, Clark & Kalogeras, Nature Neuroscience, 2002

Time

ActionAction

Awareness

of Action

Time

Action Effect

(Beep)Shifted

Awareness

of Action

Perceptual Shift

Intentional BindingHaggard, Clark & Kalogeras, Nature Neuroscience, 2002

Action Effect (beep)

250 ms Reality

+15 189 ms VoluntaryAction-46

Intentional BindingHaggard, Clark & Kalogeras, Nature Neuroscience, 2002

Action Effect (beep)

250 ms Reality

+15 189 ms Voluntary Acti-46

-27 308 ms

Involuntary TMS-induced twitch

+31

1. Stimulation of SMA reduces

sense of agency

Brain systems for conscious intention

also predict effects of actions

sense of agency

2. Basal Ganglia – preSMADopamine agonists

Binding Paradigm

• Voluntary finger movement

• 250 ms delay

• Shock to little finger

• Judge time of action or shock

• Transiently disrupt processing using repeated TMS

(cortical inhibition for approximately 30 minutes)

B. Baseline judgementsAction only

Shock only

250 msA. Physical events

Action Shock

E. Reconstruction hypothesis:

cTBS Sensorimotor hand area+32

C. Control condition: cTBS

Sensory Leg area+33

-107

-120

111

D. Prediction hypothesis:

cTBS preSMA+ 31 -86

**

• The brain generates an experience of responsibility

•... Using the same mechanisms that supply conscious intention

Fluent intention and prospective agency

• Matched for predictability: P(Effect/Action) is constant

• Compatible primes increase fluency of action selection

Sense of control

Fluency of action selection (e.g.,

through compatible priming) increases

sense of control over action effects:action effects:

Prospective, premotor sense of

agency

Neural correlates of prospective agency

1. Objective effect of fluent action selection: Compatible-incompatible primes

DLPFC

Left and Right

2. Subjective effect of reduced sense of control

rPPCrPPC

Angular Gyrus

3. Incompatible priming strengthens connectivity

DLPFC-AG

connectivity

Intention processing/

Action selectionIntention Monitoring/

Subjective sense of control

Angular gyrus: causal role in prospective agencyTMS evidence

+70ms +70ms

Prime Target JudgmentAction Effect

+70ms +70msContr

ol ra

tings

Target Effect

*`Early TMS

Abolishes priming effects

on sense of control:

AG role is necessary

for sense of agency

AG contribution is

PROSPECTIVE

Prime Target JudgmentAction Effect

So, do we have ‘conscious free will’?

• No, there is no ‘ghost in the machine’

• But the brain makes us conscious of what we are about to do

• Fronto-parietal network for action selection and monitoring makes sense of agency prospective as well as retrospective

• Our brain is a machine that can learn responsibility

• But society must give this mechanism opportunities to learn... No responsibility without equal opportunity

Thank you