Consider the following sentence: More people have been to Montreal than you have.
Would you say it’s true, or false?
Are you sure?
Take a closer look.
Does the sentence really mean what you think it does?
Does it even mean anything?
In fact, while people’s judgments vary, many report an initial sense that the sentence
is both well-formed and meaningful . . . and then they realize it doesn’t actually seem
to communicate much of anything, even if they can’t quite shake the feeling that it should.
After all, it looks like it’s trying to compare the number of people that have been
to Montreal to . . . the number of you that have?
Each half can easily be reworked into some other perfectly good sentence, like “More
people have been to Montreal than polar bears” or “I’ve been to Montreal more than you have."
But as the pieces stand, they just don’t fit together in any way that makes sense.
Like the impossible objects of M.C. Escher,
sentences like this seem okay at first glance, but fall apart under scrutiny.
Now, these Escher Sentences form only a part of a whole class of grammatical illusions,
sentences that trick us into thinking they sound okay, even when they don’t.
For instance, it takes a moment to realize that “The key to the cabinets are on the
table” should actually be “The key to the cabinets is on the table.”
But as far as plausible gibberish goes, nothing beats our Escher illusion.
And for that reason, we’re confronted with a special kind of challenge, since a lot of
the work linguists do depends on the reliability of people’s judgements about
their own language.
The fact that we can find these clear-cut disconnects, between how good something sounds
and how meaningless it actually is, seems to call all that work into question.
So, you might think we should be worried.
But like the dress that broke the internet a few years back, illusions also give us a
great opportunity to learn more about our own psychology.
And when we dig beneath the surface, it turns out that these sorts of sentences wind up
revealing something fairly important about how we process language.
To see this in action, it first helps to understand that comparative sentences like “More people
have been to Montreal than you have” are really just shortened versions of longer ones like this.
But “More people have been to Montreal than how many you have been to Montreal” doesn’t
sound any good at all.
That is, the sentence only starts to come close to working when we shorten it, leaving
out that counting phrase “how many.”
So, this could be saying something about how we understand sentences: that we don’t really
pay attention to the grammatical details at first, and that as long as the problem can
be left unpronounced, we’re happy being superficial about it and pretending it isn’t even there.
But there happens to be some pretty good evidence that something else is going on when we parse
what people have to say -- something that’s made more obvious when we look at what our
brains are doing when they encounter these illusions.
To see how, consider the statistic “1.5 billion people a year ride on the Paris metro.”
Obviously, 1.5 billion people don’t live in Paris, so that number can’t actually
be counting unique people.
In this case, it’s counting rides, meaning that such sentences are also able to track
events, and count how many times some person or other took the metro.
And experiments show that this kind of interpretation, where events get counted instead of people,
comes into play for Escher Sentences, too.
When people are asked to rate the overall acceptability of sentences like “More undergrads
call their families during the week than I do,” compared to ones describing unrepeatable
events that can only ever happen once -- like “More New Yorkers began law school this
semester than I did” -- something interesting happens.
When the event being talked about is repeatable, like calling your family, participants score
it much higher than sentences depicting something that’s singular and unique, like starting law school.
Though these illusory sentences are never rated quite as high as ordinary ones, the
results suggest that our brains are trying, and in some cases more than others succeeding,
at grafting on a meaning that counts and compares events.
In other words, the grammatical nuts and bolts we uncover when we put sentences under the
microscope are more than just a curiosity; when it comes to the language of counting
and comparing, our brains are sensitive to the details after all, even if we don’t
always consciously realize it.
Of course, there’s plenty we still don’t know, like just how deeply we process grammatical
illusions, and how they’re represented in the brain.
But research is ongoing, so you can bet more people will look into them than we have!