His question at the moment is:
"I have been tasked with running a research project. We want to use eye tracking to test how people respond to the person they are talking to. I need info on what option exist and which systems best suit my research needs."
I can forward any and all follow-up requests for details from this end.
- Mate, why do you have this thing in your eye?
- I don't know, the researcher wanted
Here's a free possible solution to the task though: https://apps.apple.com/app/apple-store/id1538790472
Eye tracking hardware is usually aimed at tracking your eyes on a screen (i.e. where you are looking on a screen). I'm not sure what system you'd have in place for a person out in the wild talking to people directly- you'd need to record their eye movements as well as what they were looking at, and sync the two.
Maybe the persons are talking via video chat? There are devices where you don't have to wear special glasses, which would make the conversation even more natural for both participants.