Task 9 Flashcards
What is the readiness potential in a nutshell?
When making a voluntary movement, there is a spike of activity in the SMA shortly before the decision is consciously made.
Where is the readiness potential commonly measured?
on the SMA
ON a modified Libet experiment, Soon et al were able to predict the decision of participants. Which brain regions were used for this prediction?
frontopolar cortex and precuneus (parietal cortex)
According to Soon’s findings, where is a decision stored until it becomes conscious?
In the precuneus
How does Soon’s study contribute to the debate of unconscious neural activity preceding voluntary decisions?
Not only can one predict the content of decisions by analysing brain activity, the brain activity is also present for too long before the decision to be explained by measurement inaccuracies
What two kinds or RPs did Libet define?
Type I: When an action is preceded by cognitive planning. Here the RP starts about 1s before the action.
Type II: When an action is spontaneous. Here the RP occurs ca 550ms before the action
What are the criteria according to which an action is voluntary?
- It arises internally
- There are no external restrictions or compulsions
- The individual has the subjective qualia of freedom to act
Why is measuring the onset time of an intention difficult?
- It is a purely phenomenological experience and thus cannot be defined externally
- A report of a qualia can logically not be immediate because it has to be processed by neural and muscle activity
How did participants in the Libet experiment report the timing of their intention?
They focused on a spot of light revolving in a circular motion. After the subject reports the intention, they are asked where the spot was at the time of the onset. To validate, the researchers gave mild shocks to the participants, who then had to again indicate where the spot was at the time of the shock. As the timing of the shock was in the hands of the researchers, they could measure the accuracy of the report as a reaction to a stimulus.
How does one arrive at 350ms when talking about Type II RPs?
Even when taking into account that people reported becoming aware of an intention 200ms before an actual motor action, this is the time that the Type II RP occurs before the action.
What is Libet’s Trigger vs Veto Theory?
The notion that RPs might be related to cerebral preprogramming of actions which are then selected or not selected consciously.
What is evidence for Libet’s Veto?
- Introspective reports of subjects who claimed to have aborted actions
- When asked to veto an action, RPs of a different form were recorded
Why is the theory of Libet’s Veto not validated?
If the theory is true, there should be RPs with no conscious action afterwards, but this hasn’t been shown experimentally yet.
What is a hypothesis for future research that Libet formulated?
Cortical activities must persist for ca 500ms before they are “adequate” for conscious awareness. Activities that don’t last as long stay unconscious.
What is the basic argument against free will?
We cannot truly be responsible for our actions, because nothing can be the cause of itself, which would be the case for some mental processes, if one was morally responsible.
