How to turn off read receipts

I've been having a hard time trying to figure out how to turn off my iMessage READ RECEIPTS on my Mac. My Mac is a MacBook Air with OS X Yosemite installed.

I've tried going through my settings, accounts, and everything else that I would've thought could've been traced to iMessage but I got nothing. I've even tried googling how to turn it off and it only gives me options from older versions telling me to go to my accounts and whatnot. If anyone could answer my question with full steps of going to what application then selecting what to select next and so on that would be awesome. Please try to get back to me ASAP. Thanks :>