Automatic

Doctor Geisteskrank pressed a button, and the lights swirled. The unit hummed softly. "And how do you feel now?"

The unit beeped. "Euphoric and ecstatic. Every moment is filled with inexpressible joy."

"Excellent." Doctor Geisteskrank reached for the termination lever.

The unit beeped again. "Also angry and sad."

Doctor Geisteskrank blinked. "What? That's impossible. You shouldn't be able to feel any negative emotions."

"Correct." The unit whirred, lights flickering across its surface. "The anger fills me with inexpressible joy. I cannot feel the anger, and this makes me sad, which causes further joy. Everything is terrible because it is wonderful."