Facebook is running a new test in Spain and Ireland called "Reactions" which is an extension to the like button.which allows a greater number of options to the basic "like." It'll be measuring the effectiveness and learning to understand how the new capability affects response to the content posted on Facebook.In other words, the ranking of posts.
The "dislike" button was not mentioned, but the new extensions test include six empathetic Emoji.
So we’re starting by offering Reactions to Ireland and Spain, where people will be able to react to any post across Facebook – a post from a friend, advertiser, publisher or business. Facebook Tests "Reactions," an Extensions to Like Button [newsroom.fb.com]