Embodied Cognition and Motor Control
Optimal Control Theory
Provide a framework to explain how movements are achieved
Route 1:Control policy --> [motor command (+ noise)] --> Forward model --> Sensory Integration --> [State estimate] --> Control policy
Route 2: Control policy --> [motor command (+noise)] --> Body and World --> [sensory information (+ noise)] --> Sensory Integration --> [State estimate] --> Control policy
Control policy
provide a set of rules that determine what to do given a particular goal and state estimate
Take into account the importance of the goal to be achieved
Motor command
output from the control policy
contains the info. about how the body is supposed to move
Noise
physiological noise
due to imperfect neural transmission along the pathway from brain to body
Forward model [1]
Input: the motor command
Output: prediction of the sensory consequences of the motor command
Body and the world [2]
Input: motor command that has been degraded by noise
Output: Produce an action that changes the state of the body and also the world
Sensory information [2]
the changes to the body and the world create sensory information
Sensory integration
Input: all the sensory information + the prediction of the forward mdel
Output: an estimate of the current state of the system
[2]: lead to uncertainty in estimating the state of the body and the world
State estimate
internal representation of the current state of the body and world
describe aspects from motor control that are not fixed by physiology & the relationship between organism and environment
Influence by the forward model and the reliability of the sensory information
Reflect how the motor command has changed things
Example of Optimal Control Theory: Tit- for- tat
A pair of people touch each other with the goal of touching back as hard as you were touched
Result
When match the force of a directly self-generated force: consistently overestimate forces
a consistent escalation of force between partners as the no. of turns increase
More accurate. when we match a force mediated by a joystick
The force we generate ourselves: inform a forward model
The prediction of the model: combined with the perceived sensory consequences of our self-generated action
leads to substantial underestimate of force
Reason
Schizophrenia
less cancellation of the effect (more accurate in matching self-directed force)
Actions are Hierarchical
Every day action: reflect continuous activity and are organized hierarchically (Lashley, 1951)
Action slips
Mistakes we make in actions often reflect hierarchial structure
Example
Insertions
E.g. turn light in when daylight
Confusions
E.g. Shaving cream on toothbrush
Perseveration
E.g. Repeatedly pick up & put down
Omissions
E.g. leave out key ingredient
Action Disorganization Syndrome
unable to complete multi-step activities
Damage: Frontal cortex (typically left prefrontal)
When the top-down signal was weakened and environmental conditions were sufficient to trigger a schema
Extreme weakening of the top-down signal
Responsible for action planning
The anatomy of the frontal cortex: reflects a hierarchical structure of action planning
Anterior portion: high level of planning
Motor cortex (The rear part of frontal lobe): simple motor acts
Embodied Cognition
Definition
the mind is not only connected to the body but that the body influences the mind
Six claims of embodies cognition (Wilson, 2002)
Cognition is situated
Take place in real world and inherently involved perception and action
Perceptual info: affects processing
Motor activity: affects environment in task-relevant ways
HOWEVER: any cognitive activity- can be in the absence of task-relevant input and output
E.g. daydreaming
Cognition is time-pressured
we need to evaluate our situation in the environment as quickly as it changes
Requires the use of cheap and efficient tricks for generating situation-appropriate action
YET: many activities don't involve time pressure
E.g. reading scientific papers
The environment is part of the cognitive system
Off-load cognitive work onto the environment
due to limited information-processing abilities
Reduce cognitive workload by making use of the environment in strategic ways
Kirsh (1994): Tetris- players use actual rotation, instead of mentally computing a solution then executing it
The forces that drive cognitive activity: distributed across the individual and the situation as they interact (rather than only the mind)
Cognition is for action
YET: Ventral steam of visual processing- engaging in perception for perception's sake
E.g. short-term memory: deployment of particular skills- verbal rehearsal
Off-Line Cognition is Body- Based
Neurophysiological evidence: Mirror neurons
neurons with special properties- represent both the sensory aspects of perceiving actions and motor aspects of how to produce the action
Discovered in monkeys
activated both when performing an action and seeing an action performed
Function: to access to the goal of the movement
Role of action recognition and conceptual processing
Vogt (2007)
Mirror neuron system : activated more strongly during observation of non-practiced action than practised action
Passive observation induced weaker activation than observation in order to imitate
Activate during active observation and motor preparation
Higuchi (2011): chords learned by observation were executed less proficiently than chords learnt by observer-imitation
Dysfunction in self-monitoring
lead to incorrect predictions, causing the misattribution of self-generated actions as externally generated
Attenuate the effect of the self-generated force as a mean to be more sensitive to forces we receive from the external source
Self-generated forces are perceived as weaker than externally generated force of the same magnitude
Self-generated forces were attenuated less
dysfunction in predicting sensory consequences of their actions
How to relate action production to action perception
integrating what u are seeing out there with what u predicted to occur out there
Forward model~ suppress the force that was generated
More important of what is happening in the external world than do it yourself
less interference of what is happening back onto u
cancellation of your own movement
difficulties in identitifying the agent- whether it is their own thoughts or speech form the other world
NOT the tradition cognitive sandwich model- cognition is between perception and action
the three components are tyed tgt
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