In a story I am working on there are 5 AI on a space station of varying levels of social, image recognition and general intelligence. At least one is good enough to pass a Turing test and do image recognition, and this is anticipated by the people running the space station. I also assume the AI is good enough to spoof most video tests (proving to me that you are human by showing me your face and turning it to specific angles won't work).

*If a robot can pass the Turing test is there any way to prove that you are human over a communication channel?* 

My ideas to get people started:

Randomness generation: a human can generate truly random numbers due to the complexity of the brain, while AI will have some deterministic way of generating numbers.

Complex scene analysis: looking at an image to determine what is going on in a scene. For example in a scene where a person is sleeping in an unnatural position while two people talk about something relating to the sleeper, the answer is, "the sleeper is secretly listening to the people talking about the sleeper" or the like.

Voigt-Kampff test: Unlikely since AI should be able to emulate human faces and responses given time and research.

***edit:*** 

The AI can attempt to deceive the test, in the same way AI now days are designed try to beat the turning test and captcha tests, except the AI is designing itself.

Also, the AI are actually AI, not Androids. They run on supercomputers and because of that do not look human or have locomotion. they can make it look like they have a human body by sending data packets of spoofed video.