Have you ever come across a sentence where something feels off the first time you read it?

The horse raced past the barn fell.

If this is your first time encountering a sentence like this, you probably had to read it a few times before you figured out that it was the horse that was falling, not the barn. Although this sentence is weird, it’s perfectly grammatical and you have no problem understanding it once you know the trick to it. What about for a sentence like this?

After the man paid the clerk asked for more money.

So what’s the deal with these sentences anyway? Sentences like these are called garden path sentences. They get their name from the fact that you feel like you are being led down a lovely garden path as you read the sentence, before you are suddenly brought to the edge of a cliff looking into the void of “ungrammaticality” and realizing that you should have taken that left turn at Albuquerque.

Garden path sentences show up rarely in natural writing, but they are used in psycholinguistic research to figure out how our brains respond to unexpected things. One way that psycholinguists can test this is to do what is called a self-paced reading task, which presents a sentence to readers one word at a time.

By presenting a sentence like this and recording how long it takes for the reader to move to the next word, we can look at the exact point where they encounter the oddness of the sentence see how they react.

Before we get lost in that rose patch though, let’s think about the possible ways that people could process something they are reading. Because English has a relatively strict word order, seeing certain words might be a good signal of what is coming next. When you are reading it one word at a time through, are you simply interpreting the most likely possibility of how the sentence will end based on what you know about your own language? Or are you thinking of all the possible ways that a sentence could go, and then cutting off the impossible ones with some hedge trimmers as you encounter more words?

Both explanations seem possible, but the second one does feel a little bit more cumbersome. Because languages are recursive and sentences could be infinitely long, trying to keep all the possible structures in your mind would be impossible. But what if we relied on the fact that our brains are essentially super computers? What if our brains understand that most sentences aren’t infinitely long and there are actually only a few things that we would have to look out for if we don’t care about what specific word follows, but instead just care about whether the sentence could continue from this point or not? Now it seems a little bit easier to imagine that we could be processing things like this.

So how exactly are our brains interpreting sentences? And how can these garden path sentences confirm that? Well, if we isolate the point of weirdness in a self-paced reading task, we can see whether readers slow down at all when they reach that point. As I mentioned before, sentences can be infinitely long, so when we encounter something like this, it shouldn’t be a surprise to our brains that the sentence keeps going and there shouldn’t be any slowing down.

But it does slow down. When readers reach this odd point in the sentence where we introduce the second verb, a significant portion of readers will take a little bit more time to figure out just what in the fertilizer is going on.

The key thing that we do need to realize though is that while our brains might be super computers that could possibly keep this idea in mind, our brains are also driven by efficiency. What this means is that, would it be worth spending all that energy to consider the infinite possibilities of sentences when we could just keep the most likely possibility in mind and revaluate the rest of the possibilities when that doesn’t work.

Let’s take another look at the sentence “the horse raced past the barn fell”. As most of you have probably noticed by now, the reason we get tripped up by this sentence is the fact that “the horse raced past the barn” could stand on its own as a sentence.

As we work our way through the sentence one word at a time our brains, being the efficient machines that they are, are trying to only consider the most likely possibility. This means that by the time we reach the word “barn” we have come across a subject “the horse”, a past tense verb “raced” and an object “past the barn”. The possibility that our brain doesn’t consider is that this entire phrase is referring to a horse that was raced past the barn, presumably by a jockey who needed to get home to water the carrots.

When we encounter the next word “fell”, the first thing our brain thinks is that “oh, barns fall all the time, so it must be the barn that fell”. After trying that angle and realizing that it doesn’t work, our brain panics and thinks “wait, I must have missed something” before it goes back to reanalyze things from the beginning with this new information in mind and makes the correct assumption that it was indeed the horse that was raced past the barn who fell.

So why didn’t they just say “the horse that raced past the barn fell” in the first place? Because then, I would have nothing interesting to write about! This is another big part of linguistics where we try to push the limits of what is grammatical and see how people will react to it. After planting a small seed of an idea in someone’s head, we are able to grow our understanding of how the human brain processes sentences. There are so many more amazing things that research has been able to teach us about language, and I can’t wait to keep sharing them with you all every week.

Thank you for reading folks! I hope this was informative and interesting to you. Be sure to come back next week for more interesting linguistic insights. If you have any topics that you want to know more about, please reach out and I will do my best to write about them. In the meantime, remember to speak up and give linguists more data.