May 2011
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The consciousness of others

Deric Bownd’s Mindblog site has information on an upcoming lecture by Geraint Rees. I have not found a paper by him on this subject as yet. The abstract quoted by DB is (here) and below:

There has been considerable interest in using multivariate decoding techniques applied to fMRI signals in order to decode the contents of consciousness. The use of such signals has inherent disadvantages due to the delay of the hemodynamic response. Moreover to date it has not been shown possible to generalize the decoding of brain signals from one individual to another. This limits the potential utility of such approaches. Here we used a different approach that circumvented these difficulties by using magnetoencephalographic (MEG) signals to decode the contents of consciousness, and to test whether such correlates generalized reliably across individuals. We recorded the MEG of 8 healthy participants while they viewed an intermittently presented binocular rivalry stimulus consisting of a face and a grating. Using a leave-one-out cross-validation procedure, we trained support vector machines on the MEG signals to decode the rivalry percept. Decoding was significantly better than chance in all participants. We then tested whether a support vector machine trained on MEG signals from one participant could successfully decode the rivalry percept of another. Again, decoding accuracy was significantly better than chance. These findings demonstrate that it is possible to decode perception independently of physical stimulation using MEG signals in near real time in a way that generalizes across individuals. Our findings indicate that certain neural mechanisms universally covary with the contents of visual consciousness, and mark a potentially important step in the design of devices for decoding the contents of consciousness in individuals unable to report their experience behaviorally.

This seems to imply that there is a level of common structure in how concepts are experienced in brains. No doubt it depends on the history of the person, their culture-language, how the concept was acquired, etc. However a common structure makes it less likely that we are each totally unique in how our consciousness operates. It may be that my ‘red’ is pretty similar to yours if it is found to be similarly held in a similar structure. We will see how this pans out in future investigations and papers.

Please let’s not start talking about mind reading just yet – I believe they are only guessing at whether someone is conscious of a face or some stripes based on comparison with the activity of some other people’s brains when they are conscious of a face as opposed to some stripes.

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