02 July 2012

The difference between Necessary and Sufficient, or, Why your emoticons should not have noses

In this crazy new cyber-world we’re living in, the entire rich array of human emotional facial expressions is being reduced to nothing more than a select few humble punctuation marks grouped together to look like caveman scratchings turned on their side.  In social media conversations, these so-called “emoticons” (also called “smilies”, for those of you not hip enough to be up on your “cyber-lingo”) have assumed the vital role normally played by our naturally expressive faces, becoming the sole representation of our emotions toward the people with whom we interact.  This is distressing in and of itself, but it’s not the point of my discussion today.

Correctly typed, the most common standard emoticons consist of virtual “eyes” and a virtual “mouth”, made using punctuation marks.  The simplest of these is the basic colon-plus-end-parenthesis – :) – though many other variations exist:  ;)  :D  :(  :’(

But a deeply bothersome trend has managed to grow and fester deep in the bowels of the emoticon world: the dash-nose.  This hideous abomination has wormed its way into all the great emoticons, a defilement I’ve never abided graciously:  :-)  ;-)  :-D  :-(  :’-(

And today, I finally figured out why that nose bothers me so much.

Humans have a very limited range of physical features they like to monitor during social interactions.  When we see another human face, we attend most to the eyes and mouth because these are the expressive features that move and tell us how we’re supposed to respond to their owner.  But a nose?  No one cares what a nose does.  A nose stays pretty much the same no matter what we’re doing, and outside of augmenting a very select few emotional expressions (e.g. the scrunch of disgust, the flaring nostrils of fuming rage), our noses are practically pointless.

Which brings me to Necessary and Sufficient.  These terms are regularly used in the sciences to describe two unique aspects of how important a certain factor is in creating a given outcome.  A factor that is necessary must be present to produce an outcome, while a factor that’s sufficient is all that’s required to produce that outcome.  So if it’s necessary, you absolutely have to have it, and if it’s sufficient then it’s all you actually need.  (And it is possible for a thing to be both necessary and sufficient – or neither.)

These are both readily testable properties.  To determine if something is necessary for a certain outcome, you just remove it and see if you obliterate the outcome.  To determine if something is sufficient to produce an outcome, you remove everything else and leave only it, and see if the outcome remains the same. 

For example, removing a necessary facial feature will prevent you from recognizing an emotional expression (like a smile), while leaving only a sufficient facial feature present will still allow you to recognize that expression.

Let me demonstrate on myself.  Say hello to me:


I hope you were gracious enough to at least offer a greeting.  I mean look at that big ol’ toothy grin.  That is a smile.  How could you ignore that kind of smile?  And how can you tell it’s a smile?  Well, the corners of the mouth are turned way up, the eyes are happily scrunched, and the nose… yeah, it’s not doing much. 

Now, let’s look at what happens when I take the liberty of altering each of these three facial features (mouth, eyes, and nose) independently. 

Let’s start with Necessary.  Is any of these three features necessary for you to be able to tell that I’m grinning at you?

The truth is, no.  As long as you have any combination of the other two features (eyes and nose, mouth and nose, eyes and mouth), you can tell I’m meant to be smiling at you.  That said, the third smile with both eyes and a mouth present is definitely the most informative of the three faces, in that it looks the most like it’s smiling.  This suggests that the nose is the least necessary component of the smile.

So how about Sufficient?  Would any of these features alone be enough for you to tell I’m still smiling?

Well, how about that?  My mouth and eyes are each sufficient, but my nose does absolutely nothing toward helping you figure out if I’m smiling.  In fact, if that nose picture still looks like I might be smiling at you, it’s only because I didn’t go and doctor the dimple out of that freakishly sculpted right cheek so you’re still getting the impression of a mouth-smile.

So what does this tell you about your use of :-) and :-( and ;-) ? 

It says that the only thing the nose-dash is doing is making you take longer to generate your virtual expression, and making others take longer to observe and evaluate it.  The extra dash adds nothing at all of value.  In fact, if you were to do my same necessary/sufficient experiment with an emoticon, you’d find that BOTH the eyes and mouth are necessary to convey information, but the nose is neither necessary nor sufficient for anything – see how it’s the exact same dash for every emoticon you type? 

The emoticon nose is, in short, a waste of a character.  This could have a profound impact on the quality of your tweets, people.  Think about that the next time you write another, “LOL :-D !!!!1!1!”


  1. Being old enough to remember the Dawn of the Internet, I have to provide a correction.

    As hard as it is to believe, the nose-included smiley (and the converse sad-face) were the first emoticons to be used (originally introduced in Scott Fahlman's legendary 1982 post).

    Dropping the hyphen came into vogue many years later, and was for a long while seen as a sign of impatient, impertinent youth. It wasn't until "the masses" took the Internet over from the professional computer scientists (cf. "Eternal September") that the trend really took hold.

    History is important. You defiler, you. ;->

    1. Clearly I am a young 'un! I never knew :). I think in this case the kiddos were right... O.o

    2. And that nose was NECESSARY. To separate the eyes. Or something. See, look at it without a nose!

      Oo <-- That just looks doofy.

  2. To be fair, your eyes also snuck two friends into the club to help out. Eyebrows, while not the ultimate factor in determining what emotion the eyes are portraying, do greatly enhance the level to which they do, I think. So, in your picture with just the eyes, could you tell you weren't sad if they were removed? Probably, but could you tell if you were beaming or just giving a little smirk?

    While I agree they may not be necessary or sufficient, I also think you shouldn't forget the eyes' posse in the equation.