New comments notifications going out to all topic subscribers?

Hello,
looking at Easydiscuss settings I have this setting

Notificatons > Notify comment participants > YES

I am not sure to understand what it does though. At first I thought it would send out new comments notifications only to the users involved in the post that has been commented (the question/reply author and the users that have commented it).
But looking at my email activities I am starting to suspect that it sends out new comments notifications to all users that are subscribed to a topic.
Could you shed some light on this?

Oh... I just noticed, I also have this setting

Notificatons > Subscriptions > Include Comments > YES

Thank you