Yes, but why? What purpose is there in pobing people's reactions to different stimuli (including being shot at!) when you're just going to send a pulse that stops everyone's heart?

There could be an answer. If Shakri was a Brainiac-like scientist who felt that humans needed to be recorded before he wiped them out, then yes, it would make sense that he'd want to see how they react to different stimuli. (It would also make sense that he'd kidnap them from hospitals.)

But he's not. Humans are vermin and he's got no interest in them at all. So it's not that.