volition

Question 1

philosophical background - are we free?

Answer 1

• Historically the key concern has been the metaphysical constraint of determinism.
  
  • Two broad positions:
  • Metaphysical libertarianism - the claim that determinism is false and hence free will exists.
  • Hard determinism - the claim that determinism is true and hence that free will does not exist.
• Both these positions assume that determinism is the relevant factor in free will but you need not agree with this assumption.

Question 2

incompatibilist

Answer 2

• Hold that casual determinism is the crucial factor in free will (true of both metaphysical libertarianism and hard determinism).
  
  • If your conscious choice is determined by something other than itself then you are not free.

Question 3

compatibilists

Answer 3

• Deny that determinism is relevant and maintain that alternative constraints are key.
• Examples include being free from coercion, or your conscious self contributing in some way to the decision rather than being the sole determination.

Question 4

is there an illusion of free will

Answer 4

· “Man can do what he wills but he cannot will what he wills” - Schopenhauer
· For an incompatibilist this position potentially denies even the illusion of free will:
- If you know you don’t ‘choose’ your desires - “I think today I will like Marmite!”
- And you know you don’t ‘choose’ your beliefs – “From now on I’m going to believe politicians are always truthful!”
- And you know you don’t even ‘choose’ your thoughts – Did you ‘choose’ to think what you are thinking right now?
- Then in what sense is there even an illusion of free will?
· For the compatibilist it poses no issue:
- E.g., if my thoughts play a part in the casual chain then I am free.

Question 5

the unconscious initiation of voluntary acts

Answer 5

· Participants watch a dot rotating on a clock face.
· At a time of their choosing they spontaneously press a button.
· They report where the dot was when they first ‘felt the urge to move’.
· Electrodes on prefrontal motor areas record the readiness potential (RP) - a negative shift in electrical potential occurring before action.
· Reported will to act was around 200ms before the action.
- Crucially, the RP began some 350ms before the reported ‘will’ to move.

Question 6

implications and limitations of the Libet study

Answer 6

· Implications:
- It appears to demonstrate unconscious brain processes precede conscious decisions to act.
- If you are an incompatibilist you might take this as evidence against free will.
· Criticisms:
- The action is trivial - the real ‘decision’ was to join the study.
- The time of ‘Will’ is subjectively reported and may vary depending on the division of attention.
- It makes assumptions about the nature of the RP, specifically that it reflects a preconscious decision process - see Schurger et al, 2012.
- It assesses only the choice of time not the choice of action.
- EEG has limited spatial resolution so it provides only limited insight into the specific brain regions involved.

Question 7

challenging the basis of the readiness potential

Answer 7

· It had long been assumed that the readiness potential reflects some form of planning or preparation for movement.
· Schurger, Sitt, & Dehaene (2012) showed how this same pattern would be present if decisions to move were made based on placing a threshold on the accumulation of random fluctuations in neural activity
- Simulations recreate the characteristic patterns and successfully make new novel predictions – the RP may not reflect a preconscious decision process

Question 8

unconscious determinants of free decisions

Answer 8

· Participants watch a stream of letters presented at half second intervals.
· At a time of their choosing they spontaneously press either the left or right button (a choice of factors).
· They then indicate which was present when they decided to press a button.
· Pattern classification algorithm identified areas of the prefrontal cortex predicting which had 7 seconds before decision.
· Represent an earlier stage in the casual chain - RPs must also have antecedent causes.
· Areas identified are known to be involved in prospective memory

Question 9

methodological limitations

Answer 9

· Electroencephalography (EEG) has limited spatial resolution but good temporal resolution
· fMRI has good spatial resolution but very poor temporal resolution
· What we really need are electrodes in your brain!
- Intracranial electrodes are sometimes used for evaluation prior to neurosurgery
- They can record the firing patterns of single neurons in awake functioning individuals
- Placement of electrodes is driven solely by clinical need
- But when clinical needs coincide with those of scientific inquiry they can provide a very rich source of data

Question 10

the Libet paradigm with single neuron recordings

Answer 10

• Study of 12 epileptic patients with intracranial electrodes in medial frontal areas
  · Replicate the ramp-like increase before movement for a subset of medial-frontal neurons (pre-SMA and SMA)
  · Time of conscious intention could be predicted by small subpopulations of these
  · However, difficult to separate prediction of intention and prediction of action
  · Previously pre-SMA was implicated for planning and volition and SMA for execution
  · But Fried et al. show that the SMA not pre-SMA contained more active neurons before the feeling of intention i.e. it occurs later in the chain
  · Suggests the feeling of intention may correspond to the moment when an unconscious plan is enacted - Volition as ‘intention in action’
• Note, still potentially challenged by Schurger’s accumulator model

Question 11

are ‘free will’ and ‘free won’t’ separate?

Answer 11

· Subpopulations of neurons decreased in activity in the pre-SMA providing evidence for an inhibitory component
· Note – where activity of some subpopulations decreases and others increases this will be invisible to fMRI
- This implies that suppression of action and its voluntary initiation are closely linked (key in disorders of volition

Question 12

the the ‘urge to move’ epiphenomenal, a simple correlate of action?

Answer 12

· Fried et al. (1991) - when applying stimulation to the prefrontal areas patients report experiencing the ‘urge to move’ without movement being made
· Desmuget et al. (2009) – also show the ‘urge to move’ can be created by stimulating parietal areas
- Demonstrates that the ‘urge’ can exist independently of action

Question 13

the emerging picture - voluntary vs stimulus-driven action

Answer 13

The motor cortex receives two broad categories of inputs driving voluntary and stimulus driven activity.

Question 14

the emerging picture - voluntary

Answer 14

· In voluntary action the loop through the basal ganglia integrates a range of cortical signals to drive appropriate actions
· Dopaminergic inputs from substantial nigra to striatum provide modulation based on reward
- Hence voluntary action can be seen as flexible intelligent interaction with current and historical context – not without cause but with a wider context

Question 15

the emerging picture - stimulus driven

Answer 15

· Information from the sensory cortices (S1) is relayed to intermediate-level representations in the parietal cortex
· From there it is relayed to the lateral part of the pre-motor cortex and ultimately onto the motor cortex (M1)
- This guides object orientated actions such as grasping

Question 16

disorders of volition - anarchic hand

Answer 16

· A condition where the person reports that one of their hands has a will of its own
· Some mixing of the terms ‘anarchic hand’ and ‘alien hand’. Generally anarchic hand refers to a situation where the patient knows the hand is there own, and alien hand where they dissociate themselves from it
· ‘Dr Strangelove Syndrome’ comes from the famous film where the German-American nuclear scientist struggles to control his right hand – which constantly wants to give the Nazi salute.
- In real life it causes considerable distress to suffers

Question 17

disorders of volition - explanations for anarchic hand

Answer 17

· Initially thought to be due to a disconnection of the hemispheres as some patients who have had a callosotomy exhibit this symptom
· Logically this fails as it would need to result from a separation between the right hemisphere motor cortex and left hemisphere areas for planning and execution – as such the anarchic hand would always be the left hand in right handed people. It isn’t (Goldberg, 1985)
- A review of 39 anarchic hand patients by Della Sala et al. (1994) found that most lesions are centred on the SMA on the contralateral side to the anarchic hand
· The notion is that the damage to the SMA impairs the voluntary circuit leaving actions guided primarily by external stimulus cues on that side
- So the actions are not the result of a second ‘will’ but rather the result of stimulus driven actions that cannot be inhibited

Question 18

disorders of volition - utilisation behaviour

Answer 18

· Damage to SMA bilaterally can result in utilisation behaviour
· Utilisation behaviour is where patients show the compulsive urge to use objects that are in sight, in an automatic fashion
· The symptom can also be observed in dementia
· The environment triggers utilisation behaviour as in anarchic hand
· But those with utilisation behaviour are often not aware the behaviour is inappropriate
· They don’t exhibit the conflict and embarrassment that those with anarchic hand suffer
- We can all relate to this behaviour e.g. environmental cues make us likely to follow our usual route home when we planned to go elsewhere

Question 19

summary

Answer 19

· The ‘I’ in language such as ‘I decided to act’ suggests a conscious ‘I’ that is distinct from both brain and body
· The evidence clearly rejects that dualist view of volition and rules out certain conceptions of free will
· It appears wrong to think of the ‘W’ (will) as prior intention located at the earliest moment of decision you might come as a shock.
· Rather the ‘W’ seems to mark an intention-in-action
· Though its existence in the absence of action suggests that it is not entirely epiphenomenal
· Voluntary action can be defined in contrast to stimulus driven actions and this approach is supported by neuroscience
- This model accounts for both normal behavioural data and that seen in disorders of volition such as anarchic hand

Question 20

summary 2

Answer 20

· We still don’t know if activity in SMA is sufficient for action - medial frontal activity in the absence of voluntary actions suggests not.
- We have only a limited understanding of the role of the parietal cortex in generating ‘urges to move’

Question 21

summary 3

Answer 21

· If the ‘decision’ is made before I’m consciously aware of it how can ‘I’ (my conscious self) be responsible for it?
· Some researchers, such as Patrick Haggard, argue that we should move toward ‘evidence based’ law that takes account of the neuroscience findings in considering culpability
- Others take a pragmatic view that irrespective of whether free will exists, laws and societal attitudes towards them are part of what shapes behaviour and so can be justified to the extent to which they help create a society that we collectively deem desirable