Forgive me, as I am but a humble interaction designer (i.e., neither a professional visual designer nor video editor) but here’s my shot at a redesigned DuoMento, taking into account everything I’d noted in the review.

• There’s only one click for Carl to initiate this test.
• To decrease the risk of a false positive, this interface draws from a large category of concrete, visual and visceral concepts to be sent telepathically, and displays them visually.
• It contrasts Carl’s brainwave frequencies (smooth and controlled) with Johnny’s (spiky and chaotic).
• It reads both the brain of the sender and the receiver for some crude images from their visual cortex. (It would be better at this stage to have the actors wear some glowing attachment near a crown to show how this information was being read.)

These changes are the sort that even in passing would help tell a more convincing narrative by being more believable, and even illustrating how not-psychic Johnny really is.