On my computer screen, a jewel-encrusted bow points skyward, with an arrow pulled back and ready to fire. In the distance, I can see a bull’s-eye planted in front of a Himalayan landscape. Slowly I lower the bow until the arrow is fixed on the target. For a second, I overcompensate and the arrow points toward the ground. I catch my breath, pull the bow up, and then release. The arrow sails across the virtual terrain and lands with a small flash at the center of the bull’s-eye.
Here’s the catch: I’m not aiming that arrow with a joystick, or a keyboard, or a mouse. I’m aiming it with my mood.
Illustration by Leo Espinoza
Technically, I’m directing the arrow by altering my physical state—the electrical resistance at the tips of my fingers and my heart rate. I’m hooked up to a biofeedback system: three sensors worn like rings around ...