How Facebook Not Having a Dislike Button Caused A Running Joke About My Friends Hitting Me Over The Head With Frying Pans

In a public Q&A in Menlo Park yesterday afternoon, Mark Zuckerberg discussed a question many of us have probably mused about: why doesn’t Facebook have a Dislike button? The little blue thumbs-up is ubiquitous across the web these days; why not a little blue thumbs-down to go with it? Zuckerberg explained that Facebook has long considered adding a kind of “empathize” button (for when a friend shares a sad or difficult moment from her life, and it feels quite jarring to respond with a Like), but that they were actively thumbs-down on the idea of having a Dislike button that would be used to express negative feedback. As Zuckerberg put it, “some people have asked for a Dislike button because they want to be able to say ‘That thing isn’t good’. And that’s not something that we think is good for the world. So we’re not going to build that.”

I don’t have any objections to Facebook’s position here, it seems very reasonable given Facebook’s aims and style. But I do think the consequences of the current setup highlight some interesting examples of a statistical concept called “Selection Bias”: if the information that reaches us on a particular topic is not truly representative of the broader pool of information out there, we can easily become biased when we try to draw conclusions. In my book Thinking Statistically I talk about selection bias in the feedback that occurs at a friendly open mic night: I pointed out (gratefully) that, even if the audience in fact contains both positive and negative opinions about your performance at such an event, the feedback that reaches you is more likely to be from the positive camp. The people who thought you did great will approach you afterwards to tell you so, but the people who thought you were mediocre will generally keep it to themselves.

In the open mic case, the mechanism of selection bias is social: good people following the friendly maxim “if you can’t say something nice, don’t say nothing at all.” Facebook achieves the same kind of positive selection-bias technologically.

Of course, it’s still quite possible for my friends to respond negatively to my photos/status/life-choices on Facebook — they just need to use the ‘comment’ feature. However, that requires much more effort than a simple click. As Zuckerberg says, “there’s something that’s just so simple about the Like button. You know if you’re commenting, a lot of the time you feel like you have to have something witty to say or add to the conversation. But everyone feels like they can just press the Like button.” In this way, the website creates a bias towards positive feedback.

The Facebook Like selection bias has a number of consequences, some obvious and some subtle. An obvious consequence is that we’ll over-estimate how popular what we say, do and feel is: If half of our friends like something we posted, and the other half dislike it, we will only see the thumb-feelings of the ones who Liked.

This effect applies to some kinds of posts more than others. For example, if I write a status saying “People who prefer to shower in the morning are weird!” then many of my fellow evening-showerers will vigorously Like in agreement, but (unless they’re willing to engage in a comment-war on enemy turf) my disgruntled morning-showering friends will just have to go cry about it in their weird morning showers. Overall, Facebook-instigated selection bias will make me overestimate the popularity of all my posts (that is, the number of people who like my posts relative to the number who dislike my posts) but especially to over-estimate the popularity of posts that split public opinion.

A second form of selection bias that Facebook creates for us is subtler and more mind-bending. While anything you post on Facebook can be Liked by others, it’s impossible for them to Like when you don’t post something. For example, there are certain topics that I’d be happy to see less of on Facebook, but which I can’t effectively encourage people not-to-post about. Maybe it’s the latest news about a celebrity I have no interest in; many of these posts are written by people who probably aren’t that interested in the celebrity either, and could be persuaded not to post about her if there were some way to communicate how many feed-readers were sick of seeing the story. But we have no way to get that message across.

Other topics I don’t want to see are personal: there was once a running joke on my Facebook wall about people wanting to hit me over the head with frying pans (don’t ask), and while some of my so-called “friends” hyper-actively Liked every pro-hitting post, there was no way for my true friends to show some love for people who didn’t post anything. So the joke continued despite (so I tell myself) a silent majority of my Facebook friends being staunchly against senseless cookery-object based cruelty. Overall, the inability to Like inactions is one more factor pushing us towards over-sharing in the world of social networks.

Of course, other popular websites offer separate upvote and downvote buttons — it all depends on the purpose of the site. As Zuckerberg says, “I don’t think there needs to be a voting mechanism about whether posts are good or bad. I don’t think that’s socially very valuable or good for the community to help people share the important moments in their lives.”

While that makes a lot of sense for Facebook, many other sites exist exactly to let a community vote about whether posts are good or bad in order to aggregate opinion about which content is most worth other an average user’s time. As such, giving an accurate representation of the ‘quality’ of a post (that is, how much the average user will probably enjoy the post) is more important to the website’s designers than the feelings of the poster; they are therefore likely to include both upvote and downvote options to try to get an accurate gauge of the true state of user opinions.

The designers of Facebook face a different challenge: While it’s certainly important that you get alerted to particularly interesting or popular things that your friends post, it’s equally important that your friends feel good about posting. As Zuckerberg says, “The Like button is really valuable because it’s a way for you to very quickly express a positive emotion or sentiment when someone puts themselves out there and shares something.”

As of this writing, Zuckerberg’s posting about the Q&A session had garnered over 50,000 Likes.


Uri Bram is the author of Thinking Statistically and other popular non-fiction.

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