Question

Why does the Time Traveler make the Psychologist press the lever?

He wants his visitors to believe him.
He is too afraid to press it himself.
He can tell that the Psychologist wants to do it.

Answer 1

The Time Traveler makes the Psychologist press the lever because, HE WANTS HIS VISITORS TO BELIEVE HIM.

"Look at the table too, and satisfy yourselves there is no trickery. I don't want to waste this model, and then be told I'm a quack"