L11 - Volition Flashcards
What did Descartes do?
- Looked at introspection philosophy = I think therefore I am
- Thought there was an organ that allows change from spiritual to physical world
How did this become psychological?
- Thought introspection was unscientific and generalised studies from frogs to humans for anatomy = using measures like RT and accuracy= involved stimulus - sensor - brain - muscles (away from spirituality and priests)
- Donders created a broken down version of this: light - eye - detection - identification - action selection - muscles
- McLelland: does this occur in a sequence or parallel
How to record objective measures?
- RT and accuracy
- Objective measures can be recorded = feel/think things whilst doing task = can be partly captured with subjective measures
How does a perfect trial feel?
- Perception during detection phase
- Consciously thinking during identification phase
- You want to please researcher/do well on task - feeling during action selection
- All realm within subjective domain - no way of knowing objectively, so need to ask
- People have conscious perception are on task and have volition
How does an inperfect trial feel?
- When you have a slow RT and no accuracy
- Conscious perception is not there, off-task and no volition
- Sometimes finger presses button, but you do not have the feeling of making that decision
- Objective and subjective measures have a common timeline = they happen at the same time and can be measured concurrently, and correlate across trials but can be weak
What is another type of imperfect trial?
- Not on-task but has conscious perception and volition (pays attention to some not others)
- They are accurate but not fast RT
- Objective and subjective measures are often inconsistent
- Are objective and subjective domains causally related
What is Hypothesis 1?
H1: Objective states of my brain-body system influence my subjective state
How does the visual cortex (objective) cause seeing (subjective)?
1) Evidence comes from brain lesions, participants had bullet holes in the back of the brain, specifically visual system
- Measured where hole was and where visual system became blind
- Loss of neurones in the visual cortex leads to loss of conscious visual experience = same for other modalities and other functions
- Disrupt objective state = disrupt subjective state
2) Evidence comes from brain stimulation: retinal degeneration caused recent blindness in patient
- Inserted array of electric stimulators under the skull occipitally, so each sensor can be triggered
- Electric stimulation of neurones in the visual cortex leads to conscious visual experience of white spots (phosphenes)
- Was replicated in healthy participants as well
What is Hypothesis 2?
- My subjective states influence the objective states of my brain
- Through mental imagery as brain chooses to think of something = they see something
What was a study looking at mental imagery and brain activity
- Asked controls to imagine tennis or spatial navigation in their home and were in an MRI scanner
- Contrasted about when people didn’t think about anything in particular vs tennis vs your house
- Different, specific brain activity was found
- Unresponsive patient in coma can do this as well
How is visuo-spatial attention orienting an example of subjective on objective?
- If we orient our attention = visual areas = we see things better
- Ask someone in a scanner and orient their attention based on quadrants, switch attention = found evidence that brain activity changes
- When people orient their attention increased visual activity in the corresponding part of the brain and decreased it in other areas = shifting resources
Volition?
Refers to capacity for goal-directed endogenous action, shared by humans and some other animals
How to define the elements of volition?
- Internal generation: volition = not externally triggered e.g electrically shocked
- Under decisional control: Volition = not habitual/automatic
- Goal Directedness: Reasons, Values, Outcomes
- Spontaneity
- Subjective experience
Describe internal generation?
- Not governed by immediacy of sensory input or motor output
- Does not mean that action occurs out of nothing, but related to many things
- When out of nothing = unrelated to a change in brain activity
What is decisional control?
- An action is volitional to the extent that it does not occur stereotypically, routinely and automatically
- What makes an act volitional its origin in a specific decision that this action is appropriate in this current context
What is goal-directedness?
Actions made for a reason - typically a representation of some desirable goal state that is achieved or advanced through the action
What is spontaneity?
- An apparently aimless generativity of action, without reasons and without specifically intended reward - ‘IDK why, I just did’
What is subjective experience?
- For an act to be volitional, one must be aware that one is acting and aware of initiating one’s act
What was Libet’s idea?
- Use the temporal relationship to infer the direction of causality
- Ppts spontaneously press a key whenever they want and ask which one came first? Self-reported action intention or change in objective brain state?
- Ask participants where was the clock when you first wanted to press the button, measured with electrodes on the skull (called readiness potential)
- Graph made showing where activity begins in the motor cortex and the reported intention to act
- The change in objective brain state precedes the self-reported intention to act
What are limitations of Libet’s idea?
- Assumes participants are able to report the time of their intentions accurately
- Temporal relationship not causation
- Causation can be better tested through direct brain stimulation
What was a study looking at movement intention after parietal cortex stimulation in humans?
- People undergoing surgery have electrodes on their brain
- Inferior Parietal Cortex: has the intention and desire to move, no muscle activity and illusion to have moved
- Premotor Cortex: when stimulated = muscle activity and movement, no intention to move and no conscious perception of having moved
What was the meta-analysis of functional localisation and categorisation of intentional decisions in humans? (neural basis of volition)
- Compare conditions in which the details of an action are instructed by external stimulus AND ppts freely chooses and generates these details for themselves
- Across 35 studies, they use reactive intention, perceptual intention, inhibitory intention and cognitive intention
- Frontal medial cortex is area when you make a volitional choice
- Dorsolateral prefrontal cortex = make goal-related decisions
- Inferior parietal cortex = differentially active = when people have a choice in tasks vs when they do not
- Understanding the neural bases of volition could help understand and treat psychosis, improving lives of schiz patients
What are individual differences in action control amongst healthy subjects?
- Impulsivity is a personality trait found in numerous psych disorders
- There are four facets: Urgency, lack of Premeditation, lack of Perserverance, and sensation seeking
- Urgency is related to psych disorders and problematic behaviour e.g gambling
- Lesion sin dorsolateral prefrontal cortex often lead to such disorders
- Urgency associated with the genetics of inhibitory neurotransmitter receptors in the brain
- Concentration of GABA in DLPFC is negatively correlated with Urgency
What is the bottom-up approach?
- Externally triggered
- Fast
- Hard-wired reflex
- Shared with evolutionary ancestors
- Orienting or fleeing responses to salient stimuli
- Inflexible
What is the top-down approach?
- Slow
- Enables voluntary action and selective attention orienting
- Inhibits prepotent actions, enables changing ones mind
- Quenches noise and improves task performance
- Resolves indecisiveness in free choice situations
- Endogenously driven, influenced by goals, instructions, preferences
