Tuesday, 15 August 2006

From Thought Experiment to Experiment

From Thought Experiment to Experiment

In 1998, Andy Clark and David Chalmers publish an article called "The Extended Mind" which began by presenting (roughly) the following intuition pump:

Situation 1: A subject sits in front of a computer and is asked to determine the fit of two geometric shapes. The shapes are arranged on the screen such that determining their fit requires the subject to mentally imagine the shapes rotating until their sockets align.

Situation 2: A subject sits in front of a computer and given the same task, only this time there is a joystick by which the subject can rotate the shapes on the computer screen. The subject can either mentally rotate as in Situation 1 or utilize the joystick. The assumption is that the joystick provides an advantage in speed.
Situation 3: A subject sits in front of a computer and given the same task, only this time superscientists from the cyberpunk future have equipped the subject with a neural implant that allows her to rotate the screen objects with only a thought. Again, the subject can either mentally rotate the shapes as in Situation 1, or she can utilize the implant to do so on-screen.

Clark and Chalmers suggest, interestingly, that all three cases utilize similar levels of cognition. That is, rotating the shapes via the neural implant is just as mental an action as doing so through pure imagination; and since the joystick utilizes the same sort of computational structure as the neural implant, the joystick manipulation is equally cognitive with imaginative. Ultimately, the conclusion is (roughly) that the mind is extended into whatever objects and/or procedures are active in cognitive processes, which are not limited to the skin/skull/body/brain.

Setting aside the theoretical disputes I have with this thesis (and there are a few), it seems that we have a real-life version of Situation 3. Or, at least, a real-life example of something resembling Situation 3. Matt Nagle, a tetraplegic who volunteered to have 96 electrodes implanted in his brain's motor cortex, closely resembles the subject described in Clark and Chalmers 3rd situation. The implanted electrodes monitor Matt's "brain noise" and interpret it as motor efforts. These interpretations are fed into a computer that allows Matt to control (loosely) an on-screen cursor. So far, Matt has limited control: he can play Pong on a good day, but still has difficulty drawing a circle (even a massively imperfect closed figure can exhaust him). Experimenters hope, however, that in the future, these implants will be part of a complete system that will allow tetra-, quadra-, and paraplegics fully recovered usage of their limbs, bypassing the damaged spinal chord that inhibits the brain messages from reaching the appropriate nervous centers.

The question that arises is whether or not Clark and Chalmers are right about the similarity in level and degreee of cognition between their situations, and Matt Nagle gives us a real-life example by which to better judge the supposed similarity. My intuition is that the similarity is illusive at best, though I'm yet to argue for it in print. I'm interested to see how other philosophers react to this (and any other similar) experiment.

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