Cool article from Sam McDougle at The Beautiful Brain on the neuroscience of free will. Free will is based on the idea that we are free agents, able to decided for ourselves how we move this mystery we call living. So in talking about free will, philosophers refer to a "sense of agency" (SoA), the perception that our lives are our own.
This really is a complex subject, especially when neuroscience enters into the equation:The "sense of agency" (SA) refers to the subjective awareness that one is initiating, executing, and controlling one's own volitional actions in the world.[1] It is the pre-reflective awareness or implicit sense that it is me who is presently executing bodily movement(s) or thinking thoughts. In normal, non-pathological experience, the SA is tightly integrated with one's "sense of ownership" (SO), which is the pre-reflective awareness or implicit sense that one is the owner of an action, movement or thought. If someone else were to move your arm (while you remained passive) you would certainly have sensed that it were your arm that moved and thus a sense of ownership (SO) for that movement. However, you would not have felt that you were the author of the movement; you would not have a sense of agency (SA).[2]
Normally SA and SO are tightly integrated, such that while typing one has an enduring, embodied, and tacit sense that "my own fingers are doing the moving" (SO) and that "the typing movements are controlled (or volitionally directed) by me" (SA). In patients suffering from certain forms of pathological experience (i.e., schizophrenia) the integration of SA and SO may become disrupted in some manner. In this case, movements may be executed or thoughts made manifest, for which the schizophrenic patient has a sense of ownership, but not a sense of agency.
Regarding SA for both motor movements and thoughts, further distinctions may be found in both first-order (immediate, pre-reflective) experience[3] and higher-order (reflective or introspective) consciousness.[4] For example, while typing I have a sense of control and thus SA for the on-going action of typing; this is an example of SA in first-order experience which is immediate and prior to any explicit intellectual reflection upon the typing actions themselves. In this case, I am not focusing on the typing movements per se but rather, I am involved with the task at hand. If I'm subsequently asked if I just performed the action of typing, I can correctly attribute agency to myself. This is an example of a higher-order, reflective, conscious "attribution" of agency, which is a derivative notion stemming from the immediate, pre-reflective "sense" of agency.
A number of experiments in normal individuals has been undertaken in order to determine the functional anatomy of the sense of agency. These experiments have consistently documented the role of the posterior parietal cortex as a critical link within the simulation network for self-recognition. Activation of the right inferior parietal lobe/temporoparietal junction correlates with the subjective sense of ownership in action execution.[9][10] Posterior parietal lesions, especially on the right side, impair the ability of recognizing one's own body parts and self-attributing one's own movements.[11]
Accumulating evidence from functional neuroimaging studies, as well as lesion studies in neurological patients indicates that the right inferior parietal cortex, at the junction with the posterior temporal cortex (TPJ, temporoparietal junction), plays a critical role in the distinction between self-produced actions and actions perceived in others.[12] Lesions of this region can produce a variety of disorders associated with body knowledge and self-awareness such as anosognosia, asomatognosia, or somatoparaphrenia.[13] Electrical stimulation of the TPJ can elicit out-of-body experiences (i.e., the experience of dissociation of self from the body).[14]
The investigation of the neural correlates of reciprocal imitation is extremely important because it provides an ecological paradigm (a situation close to everyday life) to address the issue of the sense of agency.[15] There is good evidence that reciprocal imitation plays a constitutive role in the early development of an implicit sense of self as a social agent.[16] In one functional neuroimaging experiment, participants were scanned while they imitated an experimenter performing constructions with small objects and while the experimenter, while performing such a manipulation, imitated them. Across both conditions, the participants' sense of ownership (the sense that it is I who am experiencing the movement or thought) as well as the visual and somatosensory inputs are similar or coincide. What differs between imitating and being imitated is the agent who initiated the action. Several key regions were involved in the two conditions of reciprocal imitation compared to a control condition (in which subjects acted differently from the experimenter), namely in the superior temporal sulcus, the temporoparietal cortex (TPJ), and the medial prefrontal cortex.[17]
Another approach to understanding the neuroscientific underpinnings of the sense of agency is to examine clinical conditions in which purposeful limb movement occurs without an associated sense of agency. The most clear clinical demonstration of this situation is alien hand syndrome. In this condition, associated with specific forms of brain damage, the affected individual loses the sense of agency without losing a sense of ownership of the affected body part.
Thank you Wikipedia.
Read the whole article.Will You Will?
By Sam McDougle
The Neuroscience of Free Will
“Consciousness” and “Free Will” are complicated topics. Actually, researchers wish they were merely “complicated” topics – I would go for “staggeringly complex.” “Philosophically and scientifically baffling” has a nice ring to it as well.
There is a two-pronged attack going on in academia in the quest to understand the feeling of “I,” involving both theorists and laboratory neuroscientists. Theorists, like Daniel Dennett or Daniel Wegner, use a wide panoramic lens to peer into the big philosophical conundrums of consciousness and free will. Is the physical brain the engine of the train of experience, and the feeling of “consciousness” merely steam? Or is consciousness the coal driving the brain-engine forward? Is volitional action really caused by our conscious decisions? Or is “deciding” simply an illusion of control superimposed on deterministic biology?
These are huge questions that will likely remain unanswered for years to come.
Neuroscientists prefer to use a microscopic lens to study consciousness and free will. Without losing sight of the big puzzle, they work tirelessly to fit little pieces together, one by one, and their questions are usually pointed and a little more manageable: What is the role of the posterior parietal cortex in the subjective feeling of control? How does the pre-supplementary motor area contribute to voluntary action?
Research on these smaller questions offers much-welcomed relief from philosophy-induced headaches.
***
The most important aspect of free will is the impression that we consciously control our bodily actions. The official name of this feeling is the “Sense of Agency” (SoA). A basic example of SoA would be my current feeling that, “the words I am typing on this screen are a result of the control I have over the movement of my fingers on the keyboard.” Furthermore, I sense that, “these are not someone else’s fingers, nor do I think that the appearance of words on the screen is a coincidental accident – there is a causal relationship between my typing and the appearance of the words.”
There are two main theories concerning the psychology of SoA — I’ll try to describe them as succinctly as possible . . . .
No comments:
Post a Comment