I though this looked like a neat concept back when it came out, but wasn't sure how well it would work. At the time it was also almost $100 for the thing, which seemed like a bit much to spend on an experiment of this nature. However, at Munchkin Market my wife found it for $8. Looking online it seems like it's now down to about $50, but $8 is still a whole lot better. So anyway, I now have a brainwave measuring device, albeit a very simple one. Since the sensors only run around the headband my guess is that the Mind Flex is not all that sensitive, certainly not up to what a cap covered in sensors could measure. After playing around with it for a bit, though, I found what it did measure interesting at the very least.
Concentrating on any object in the room as you meditate will raise your brainwave frequency all the way to the top of what the display indicates, probably around 30 Hz. This is considered the top of the Beta range. Studies with advanced meditators have shown that brainwaves in the Gamma range seem to correllate to experiences that meditators describe as approaching samadhi. I also tried it with one of my Tibetan images, but it seems to be harder to get the frequency to the top of the range with a flat image rather than a three-dimensional object. I'm not sure what's up with that. Next on my list is to sit down and do a full meditation session to see what happens to the frequencies.
One thing I will say is that according to the Wikipedia article some skeptics have claimed that Mind Flex doesn't measure anything and only appears to work because of the illusion of control. However, I found that this was most emphatically not the case. By shifting my attention different ways I could move the indicator up, bring it down, and even hold it at an intermediate level - though that's a little more difficult than running it high or low. Maybe with untrained meditators the frequency jumps all over the place and appears to be nearly random, but that was not what I observed working with the device. The changes in the lights seemed to match my state of consciousness pretty closely, with nothing more than a lag of a second or so between the headset and the base.
I'm now wondering what I would need to build some sort of computer interface for the headset. The base and headset communicate wirelessly, so there must be some sort of signal that I can intercept. I did find an article online about wiring into the chip directly, but if I can get a wireless interface to work that would be a whole lot better for using it during magical rituals. The headset appears to have a short range, but I would be okay with putting some sort of modified base station in the center of my altar. I just don't want to be circumambulating with a wire trailing behind me and potentially knocking over things.
It also occurs to me that I could see about testing it out with a couple of my other devices. I have a Photosonix Nova Pro, for example, and it would be neat to see if the Mind Flex measures that brainwave frequencies that the different programs are supposed to be producing with light and sound. I also am thinking that it would be a good test to see if brainwaves correspond to the EMF phenomena that I've recorded during rituals, or the behavior of the Eggley wheel or some similar instrument. I may not have a real brain scanner yet, but there are still things to try out with the Mind Flex while I'm waiting on a decent consumer model to become available.