Can you have image-based questions? Something like "What comes to your mind on seeing this?"
The barrier to entry is small because there's no "right" answer (eg. Ned Kelly, Bushranger, Outlaw, Bloke with a gun and silly helmet, etc.) but it still goes a long way toward proving that there's half a human on the other end.
Haha thanks - that's the idea! It's an easy question that shouldn't turn people away. Creative answers would be arguably encouraged, as it's all the more proof of a real person answering!