Brain Waves - Magic Trick

You hand an ordinary deck of playing cards to a spectator for examination. They may shuffle the cards if they wish. You then slowly go through the face-down cards and ask the spectator to say “Stop” five times, selecting five random cards. (This is a completely free selection.)

You hand the iPhone to the spectator and ask them to open the Brain Waves app. You reveal four of the cards one by one, and the spectator enters them into the app by selecting the suit and rank using the picker. Once the cards have been entered, you tell the spectator that you need to concentrate so the iPhone can pick up your brain waves.

Next, you ask the spectator to shake the iPhone. After a shake, the back of a single playing card appears in the app. You ask the spectator to tap the card, and it flips over.

You then reveal that this card is the same as the fifth card the spectator selected!

The app includes a detailed explanation of how the effect works and how it can be performed.
Optimized for system-wide light and dark mode (see screenshots).