When You're Silently Reading, Is It Really That Silent?

Not really.

From a piece in Scientopia...

It's a relatively easy hypothesis to assume that if we are "reading aloud" when we read silently, we should see increases in activity in the auditory-related areas of our brains, particularly things like the temporal voice area (which is particularly sensitive to voices as opposed to sounds in general). There are some fMRI studies that have indeed shown activity in this area during silent reading. But when does this occur? Is it part of the processing of silent reading? Do we have to read "aloud" to ourselves to read silently? Or is it something that happens later on, where we insert the voice reading "aloud" in our heads to aid us in comprehension?

This isn't something that fMRI can answer. But it is something you can answer if you have electrodes implanted in the right places. While most people don't walk around with electrodes in their heads and are unlikely to volunteer to do it for science, there is a small population of people who DO. Some of these people have severe intractable temporal lobe epilepsy. One of the last-ditch treatments for this is often the resection (taking out) of the temporal lobes. But before this is done, you have to determine if the seizures really are the result of temporal lobe activity, and where the seizures start (you really don't want to have to take out more than you absolutely need to). So patients get implanted with electroencephalographic electrodes that are underneath the skull and over the temporal lobes to monitor their activity.

And of course, if you've got the electrodes anyway, you might as well participate in a reading study.