Wednesday, May 15, 2013

Fun with Flying Pigs: The Importance of Context in Language Comprehension

How do we understand the phrase flying pig? This sounds like a silly question (and later on I will show that it is) but people can get quite emotional about it. In a recent blog post, for example, Greg Hickok took Ben Bergen to task for things Ben said about a flying pig in an interview on NPR.

Flying pig you ask? Yes, it was a comment that Ben made about a flying pig that set Greg off in what someone on Twitter called an “epic rant.” An epic rant about a flying pig: what could be better than that? (In truth the rant was about more than just the pig but I hope you forgive my fascination with the pig.)

What did Ben say about the pig? Here is the transcript of his interview. Ben first sets the NPR listeners’ minds at ease: a flying pig isn't something that actually exists in the real world.  I like the no-nonsense approach here, but then Ben immediately veers into the danger zone: Yet when we read those words we see one in our mind's eye. Most people see a pig with wings above its shoulders… But some people imagine a pig with a cape, flying like Superman.

Uh-oh, epic rant alert! Ben should not have said this because now Greg is all over it: Or maybe I combine pig with my experience flying on 737s and imagine a pig sitting in coach ordering a Diet Coke.  Or should I combine pig with my baseball experiences and picture a mini pig being used as a baseball and getting smacked out to center field.  Hold it right there, sir! To have a pig drink Diet Coke is one thing but to miniaturize it and then smack it out to center field, well that’s just cruel.

What does all of this have to do with language? Thought you’d never ask. Ben argues in the interview that we understand the phrase flying pig by performing mental simulations based on our previous experiences: a flying pig has meaning to us because our brain is using things we have seen — pigs and birds — to create something we've never seen. This is one way to think about it but you really don’t have to think of it in terms of visual representations, abstract symbols will do just fine.

Traditional cognitive theories assume that we have networks of nodes that represent concepts and their connections. Those connections specify the relation between the concepts. For example, BIRD might have CAN FLY and HAS WINGS as features. AIRPLANE would have the same features (obviously, because airplanes are not identical to birds they have different features as well, such as HAS LEGS and HAS WHEELS). PIG does not have these features but when it becomes associated with FLYING, HAS WINGS might become temporarily activated and associated with PIG. In this case, there is no mental simulation that involves the visual system but we would still end up with a winged pig.

As Ben and Greg have just shown us, there are other ways to think of a flying pig. Ben argues that these can also be represented via mental simulation. That’s possible but they can also be represented by the amodal-abstract-arbitrary symbol system that I just described (or a variant of it). So Ben and Greg are both wrong. Ben is wrong to imply that mental simulation is the only way in which multiple interpretations of FLYING PIG can be generated and Greg is wrong to view the unrestrained generation of flying-pig interpretations as a unique weakness of mental simulation, because the same criticism can be leveled at traditional models of semantic representation.

Ben and Greg both ignore an important issue. Without sufficient context, any phrase is open to multiple interpretations. We really cannot say much about the interpretation of flying pig in isolation. Suppose someone came up to you at a party and said: I saw a flying pig. I highly doubt that you would generate all the interpretations that Ben and Greg came up with. Your response would probably be more like Wow, someone must have spiked your drink, bro or, if you’re more polite, Enjoy the rest of the party, after which you would hurry to a far corner of the room pretending to have spotted an old friend.

Context serves to restrict the number of potential interpretations. Only (psycho)linguists and philosophers study language snippets in isolation. This has led to fruitless, decades-long debates about the interpretation of sentences no sane individual would ever utter, like The horse raced past the barn fell or The present king of France is bald.

So let’s create a context. Suppose there is a guy named Greg who lives in Macon, Georgia. Greg’s brother Duane is a huge Game of Thrones fan. Huge fan. So huge in fact that he has become interested in medieval warfare and has built his own trebuchet. Unfortunately for Duane though, there are no boulders on his property to hurl at targets. Resourceful guy that he is, Duane quickly realizes the solution is living right next door. His neighbor, Dickey, is a pig farmer. He buys all of Dickey’s pigs and each night (non-miniaturized) squealing pigs (talk about live ammo) are being launched at targets. One day Duane’s wife, Jessica, says to Greg: I’m gettin’ sick of them flyin’ pigs.

Small chance Greg will interpret this (either though mental simulation or through amodal symbol manipulation) to refer to a pig with a cape or a pig ordering Diet Coke on a plane.

Making the relatively uncontroversial assumption that in most contexts flying primes wings, we can predict that this priming effect is erased by the context of the story. In fact, there is a study showing exactly this. In most contexts, peanut and salted are associated, meaning that peanut primes salted. But let’s uppose that we have a story in which the peanut is a protagonist who feels emotions, such as happiness and sadness. Normally peanut would not prime sadness but in the context of the story, it should and it should not prime salted. This is exactly what Mante Nieuwland and Jos van Berkum found in their cool study.

So Ben and Greg are both wrong. The promiscuity of interpretations of flying pig is not a pro (Ben) or a con (Greg) of simulation theory. It is a problem that occurs when we take language out of context and study “textoids.”

In closing, here is an appropriately titled song by Pink Floyd. It sounds a little tinny but the guitar solo is great.


  1. Pink Floyd entered my mind as soon as I started reading. And, I got a huge payoff in enjoyment when, in the end, it turned up!


    (Now, what does that mean for comprehension? Or what kind of information does that give us about each other?)

  2. I'm just speculating of course, but I think it has to do with common ground. The phrase flying pigs primes the Pink Floyd song, provided you have this title in your long-term memory (or if you were primed with professor of course;)). Because there are quite a few references to popular music (mostly from that period) in my posts (can't help it), you had the expectation that a reference to Pigs on the Wingwould come. And it did.

  3. Well, didn't you notice how particularly INTELLIGENT that earlier post was?

    But, I started thinking about another issue. I'm born and raised in Sweden. My introduction to Pink Floyd happened prior to me moving to the US in the early 80's. So, I think this is my first encounter with the notion of "when pigs fly". We don't have a (closely) similar saying in Sweden, and as I was trying to find synonymous sayings, I kept coming up with American/english ones (When hell freezes over, a snowball's chance in hell), and could not come up with a single swedish one, although I'm sure there are figurative sayings meaning "never" in Swedish. Just can't recall them (and, hell, Swedish is so my very much native language, and I've been back for close to 9 years).

    Which, suddenly, made me think of Alan Parson's Raven song...

    (Never more). (Hey I like the music refs).

    1. There probably is an expression in Swedish, right? Ik kan think of two in Dutch: When Easter and Pentecost ("Pasen en Pinksteren") are on the same day and When calves are dancing on the ice. For all I know, the latter may not be impossible in Sweden.;)

  4. I love that peanut priming study - very cool.

    As I said on Twitter, I think this is actually pretty crucial. Word meaning doesn't live in the words, it lives in the language event the word is nested in. There's two ways to think of this; as 'word meaning modified by context' or 'meaning from the word/context system'. I prefer the latter, because it's directly analogous to the Thelen & Smith A-not-B analysis. People thought the error was due to 'object concept modified by developmental status' but it actually lives in the 'reaching to find a hidden object with an immature reaching system' system. There is no evidence for the object concept so there's nothing to be modified, if you see what I mean.

    1. I agree that word meaning doesn’t live in the word per se. In fact, this is the basic idea behind our 2002 “eagle” study in Psych Science . The prepositional phrase that describes the location of a target object constrains the shape that the object can have. An eagle has its wings stretched out when in the sky and drawn in when in the nest . So it’s basically only the noun in the PP that is varied; the preposition itself stays the same. This minimal difference affects how we represent the eagle.

      The linguist Pustejovsky has a theory of “word meaning modified by context” (which by the way does not account for the eagle effect). I think the 'meaning from the word/context system' is an interesting idea as well. It is not clear to me if it would extend to displaced language use, i.e., when language is used—as is often the case-- to describe situations that are not in the here and now. So that’s why I am on the fence.

      I do however think that the relentless presentation of words/sentences that has become the staple of psycholinguistics is often problematic because it ignores context. If you, despite the lack of context, find evidence of deeper comprehension (as I do), it is not so problematic. Your experiments are biased against finding effects of deeper comprehension, so if anything you’re being conservative and likely underestimating effect sizes. But if you use this kind of experiment to claim that comprehension is shallow, then you have a problem. You have set up your experiment such that people will process the stimuli in a shallow fashion. People normally don’t read sequences of dozens and dozens of unrelated and uninteresting sentences out of context.

      I’m a little focused on social priming now, but this is a topic that I plan to address in the future.