readiness potential
= RP = slow negative shift in electrical potential generated by the brain (SMA), beginning up to a second before a self-paced, apparently voluntary motor act
- RP I: only in trials where subjects reported planning/preparation to act
- ramp-like RP with an average onset at about 1050ms before motor act - RP II: the one uniquely associated with an exclusively endogenous volitional process
- average onset at about 550ms before motor act
voluntary action/will
= W = free will
- arises endogenously
- no externally imposed restrictions/compulsions that controls one’s initiation & performance of the act
- one feels introspectively that they are performing the act voluntarily + that they are free to (not) start the act as they wish
Libet study
- perform a prescribed motor act (flexing finger) at some time (free to choose) after the start of each trial
- pay close introspective attention to the onset of the urge to perform the act
- W: experience of the first awareness of wanting to move
- indication of the timing: there was a light spot going around a clock face and participants later had to say on what number it was when the urge occurred
- should not plan the act, should be “spontaneous”
- -> compare time of onset of the conscious intention to act (W) + the time of onset of associated cerebral processes (RP)
- -> compare W + the actual time of the voluntary motor act (indicated EMG)
Libet study
- validity of W
- skin stimulus was delivered at an irregular, randomised time after the start of each trial and the subject reported the time of his awareness of the stimulus
- discrepancy between the subject’s reported timing and the actual stimulus time could be objectively determined
- skin sensations were usually reported to occur a little in advance of the actual delivery time, but this did not affect the onset of RP and W
Libet study
- result
- “physical” (= cerebral process, RP) precedes the “mental” (= conscious intention, W)
- W = on average 200ms before muscle activation
- RP = 535ms before muscle activation –> consistently in advance of W
- reported times for W were essentially the same for fully spontaneous acts + those with some preplanning
Libet study
- conclusion
- if a conscious intention to act would actually initiate a voluntary event, it would coincide with the specific cerebral processes that mediate the act
- voluntary acts can be initiated by unconscious cerebral processes BEFORE conscious intention appears
- brain decides to initiate or at least prepare the act before there is any reportable subjective awareness of the decision
- however, conscious control over the actual motor performance of the acts remains possible
- conscious volitional control may operate not to initiate the volitional process, but to select + control it
- either by triggering the final motor outcome or by vetoing the progression to actual motor activation
- free will is restricted/ different to what we would think –> selects voluntary outcomes rather than initiate them
Libet study
- conscious volitional control/veto
- motor potential (MP) is generated at about 50ms before muscle EMG
- there remains a period of about 100-200ms (between W + MP) in which conscious control could block the onset of the MP
- -> VETO
- subjects reported that during some of the trials a recallable conscious urge to act appeared but was suppressed before the actual movement occurred
- subjects were asked to develop an intention to act and to veto about 100 to 200ms before the prearranged clock time
- pre-event potential was still recorded before the prearranged time, even though no muscle activation occurred
- preparatory cerebral processes associated with an RP can + do develop even when intended motor action is vetoed at approximately the time that conscious intention would normally appear before a voluntary act
Soon study
- directly investigate which regions of the brain predetermine conscious intentions & the time at which they start shaping the motor decision
- freely paced motor-decision task
- fixate on centre of screen where a stream of letters was presented
- at some point chose to press one of two buttons (left/right)
- in parallel they should remember the present letter
- after a response mapping screen appears: second button press to choose the letter
- pattern-based decoders were trained to predict the specific outcome of a subject’s motor intention by recognising characteristic local brain patterns associated with each choice
Soon study
- results
- intentions reported to be formed 1s before movement
- two brain regions encoded the outcome during execution phase
- -> M1 & SMA
- two brain regions prior to conscious decision encoded with high accuracy whether the subject was about to choose left or right
- -> frontopolar cortex: first cortical stage at which actual decision was made (7s before motor decision)
- -> parietal cortex: precuneus involved in storage of the decision until it reached awareness
- decoding of the time decision was possible 5s before
- -> pre-SMA & SMA
- frontopolar + parietal cortex only knew just before the motor decision
Soon study
- conclusion
- outcome of a decision can be encoded in brain activity of prefrontal + parietal cortex up to 10s before it enters awareness
- -> SMA is not the ultimate cortical decision stage where conscious intention is initiated
- there is a double dissociation in very early stages btw brain regions that shape the specific outcomes + those that determine the timing
- -> at later stages (right before conscious decision) both regions decode both
- delay reflects the operation of a network of high-level control areas that begin to prepare an upcoming decision long before it enters awareness
- -> unconscious precursors of motor decision originate in frontopolar cortex –> influence build-up of decision-related info in precuneus and later SMA (there it remains unconscious for up to a few seconds)
Libet study
- outcomes
- allowed to determine long-term determinants of human intentions preceding the conscious intention far beyond the few hundred milliseconds observed over SMA
- allowed to separately investigate each brain region + determine how much info each region had about the outcome of the decision
- allowed to identify whether any leading brain activity indeed selectively predicted the outcome, rather than reflecting potentially non-specific preparatory processes
moral responsibility
- basic argument
= we cannot truly/ultimately be morally responsible for our actions
1) nothing can be causa sui (= cause of itself)
2) in in order to be truly morally responsible for one’s actions, one would have to be causa sui (at least in certain crucial mental respects)
3) therefore, nothing can be truly morally responsible
- -> to reject, one must reject (2) the premise that to truly be morally responsible, one must truly be responsible for the way on is
basic argument
- main claim
= people cannot be supposed to change themselves in such a way as to be/become truly morally responsible for the way that they are and hence for their actions
1) one is the way one is (C-features) as a result of heredity & previous experience
2) one cannot at any later stage try to change the way one already is to accede true moral responsibility
3) change will be determined by the way one already is as a result of heredity + experiences (S procedure)
4) if the changes are not due to those factors, they’re due to indeterministic/random factors, for which one isn’t responsible either
true moral responsibility
= if it makes sense to suppose that it is just/fair to reward/punish someone
- basic argument says there is no punishment/reward that is ultimately fair
- situations of choice that regularly occur in human life are the reason why we believe in true moral responsibility
- -> feel like a self-conscious agent that can deliberate what to do
determinism
= doctrine that all events (incl. human action) are ultimately determined by causes regarded as external to the will
alternatives to basic argument
- compatibilism
- one can truly be morally responsible even if determinism is true
- one is truly responsible as long as the actions are not caused by a certain set of constraints (e.g. OCD/ threat/…)
- -> “premise that to truly be morally responsible, one must truly be responsible for the way on is”: comes out false because one doesn’t need to be truly responsible for how one is
compatibilism
- disadvantage
= fails to amount for any sort of true moral responsibility
alternatives to basic argument
- incompatibilism
= believe that freedom + moral responsibility are incompatible with determinism
alternatives to basic argument
- libertarianism
= we are free + morally responsible agents, therefore determinism is wrong
incompatibilism + libertarianism
- disadvantages
- how can falsity of determinism help?
- -> moral responsibility depends on the falsity of determinism but determinism isn’t falsifiable
alternatives to basic argument
- third no-name option
= accept that one cannot ultimately be held responsible of one’s character/ personality/ motivational structure (CPM), no matter whether determinism is true or false
–> one can still truly be responsible for one’s decisions + actions because one’s self (S) is independent of one’s CPM
third no-name option
- disadvantages
- whatever S decides, it decides as it does because of the way it is –> so S must be responsible for the way it is in order for the objection to hold
