One group was told that a glitch in the software would cause the correct answer to show on the screen if they hit the space bar—but only they would know they’d hit it.

One group was told that a glitch in the software would cause the correct answer to show on the screen if they hit the space bar-but only they would know they'd hit it.

If the students did not use their cell phones, there would be a photo on the screen of the bracelet to show that.