One recent Friday night, at a software-development firm’s warehouse in San Francisco, Mikey Siegel called to order the hundred and fifty or so meditators, video gamers, and technocrats who had gathered for one of the city’s biweekly Consciousness Hacking meet-ups. Siegel, the primary organizer of the event and the founder of a Santa Cruz–based biofeedback startup called Bio Fluent, asked the crowd, men and women of widely varied ages, to go around the room introducing themselves in three words. Everyone laughed, but took the task seriously. The introductions moved quickly through the room in a brisk beat:

“Me Technological Cartoon”_

“Heather Curious About Brains”

“Neuromore Singularity Atom Here”

“Dan Thoughtful Helpful Software”

“Harry Self-Modification Exploration”

“David Psychiatrist Technological Retarded Curious”

“Jordan Moving Meditation Butts”

“Juliana Joel’s Aunt”

“Ben Existence Existence Existence”

“Zohara Chocolate Maker Meditation Awareness”

“Lila Awake Empath Warrior”_

San Francisco’s Consciousness Hacking meet-ups are an opportunity for engineers, entrepreneurs, and enthusiasts to test the fleet of still experimental self-examination technologies emerging largely from Silicon Valley. The region’s tech community is a body culture, obsessed with monitoring and perfecting its food (Soylent), fitness (Fitbit), and physiology (23andMe). As brain-wave technologies get cheaper and more popular, some company founders hope that consumers, who seem to be acclimating to devices like the increasingly ubiquitous Fitbit, will consider other, more cumbersome devices and procedures. Consciousness Hackers are a kind of self-selected early market-research group. Tonight, that was especially clear.

For the evening’s first demonstration, Siegel helped attach electrodes to the temples of Adam Goyer, a volunteer test subject, then cued Eugene Sinkevich, an electrical engineer, to start the current. “We are at the frontier,” Siegel said, looking out at the crowd as no more than two milliamps ran through Goyer’s head. “We’ll be able to tell our kids that we used to hook up arbitrary electrical signals to our brain.”

Goyer sat still for several minutes, flinching only slightly. Then it was over. How did he feel?

“First, let me say I’m really nervous about putting electricity through my brain. The first wave felt like a tingling on my forehead, and I guess I’m smarter afterward, sure. Then the second wave of tACS [transcranial alternating-current stimulation, a type of stimulation in which the flow of the charge varies] I kinda felt woozy, not in a bad way, but kind of like I’m on a boat. Then the third one, I definitely had some flickering, some eye flickering: in the outside of your eyes it’s like a flash, like a strobe.”

Siegel looked toward Sinkevich, who had brought in the electrode device, which is called foc.us (tagline: “Take Charge”). Foc.us, and peer products like Brain Stimulator and the forthcoming Thync, are being positioned for casual consumers. They are already popular with video gamers, some of whom believe that the shockwaves create clarity and lead to a “flow state.” (Elif Batuman recently wrote for the magazine about debates over the effectiveness of transcranial direct-current stimulation, or tDCS, in which a low charge is delivered to the brain.)

The strobe reaction Goyer had reported seemed to Sinkevich to be less than ideal. “Maybe we tune that,” he said, before offering everyone a fifteen-per-cent discount.

After the foc.us demo concluded, Ariel Garten, the co-founder of InteraXon, presented her company’s latest product, Muse, a lightweight electroencephalograph that wraps around your head and passively reads your brain’s electrical activity in order to help the user self-monitor while meditating, thereby improving mental fitness. This May, InteraXon received a new, ten-million-dollar round of venture capital, bringing its total funding to $17.2 million; its investors include Ashton Kutcher.

Garten began by describing Muse’s ability to distinguish a calm mind from an active one, then got into one of its more cutting-edge features, which, though it has not been rolled out commercially, a hacker can set up. With the hack in place, she said, once the user has succeeded in learning to control brain activity (specifically, to vary the speed of electrical pulses by closing his eyes or breathing deeply), he could potentially use the feature to interact with and control physical objects. Garten described it as “telekinesis.”

“You can make your phone vibrate from a distance. We’ve made thought-control toasters,” she said. “There’s a thought-control beer tap in our office. I have a levitating chair, and you close your eyes and relax and it goes back down.” Many in the audience gasped. She later reiterated that these weren’t out-of-the-box capabilities, but acknowledged that, yes, she had adapted a Muse to create a levitating chair.

After a third presentation, a demonstration of an inexpensive computer, capable of reading brain waves, that had arisen from a DARPA program to fund D.I.Y. neuroscience, audience members stood and offered some casual general announcements, which suggested the uses to which the night’s demos might be put. “Hello, I’m Mike,” one fellow said. “My Burning Man camp has a massage tent, and I thought it would be cool to bring a device like the Muse and hook it up to lights and the massagee, so the lights change depending on your mood. So if you know of anyone who’s done that, I’d love to hear from you.”

As the meet-up ended, a few dozen people went over to the foc.us table to test out the controller and headset. The line was long, so I picked up a different device, the moovs, and placed one of the slimy jelly pads on my face. I looked up and saw eyes twitching all around me. Best, I decided, not to press go.