The Sentence as a River: What is Information Structure?

At its heart, information structure is about how we manage our audience’s attention. We don’t just throw facts at people; we build upon what they already know. Every sentence is a delicate dance between the familiar and the novel, guiding the listener from “here we are” to “this is where we’re going next.”

The Building Blocks: Old and New Information

The entire concept of information structure rests on a simple, yet powerful, distinction between two types of information in any given sentence:

• Old Information (The Topic): This is the information that the speaker assumes is already known to the listener. It might have been mentioned in the previous sentence, or it might be obvious from the physical context. It’s the anchor, the starting point, the shared ground. In linguistics, this is often called the topic or theme. It answers the implicit question: “What are we talking about?”
• New Information (The Focus): This is the fresh, important, and unpredictable part of the sentence. It’s the reason for speaking in the first place—the new insight, the answer to a question, the resolution of uncertainty. This is known as the focus or rheme. It answers the implicit question: “What are you telling me about it?”

Let’s look at a simple exchange:

“What did Anna eat for breakfast?”

“Anna ate oatmeal.”

In the answer, “Anna ate” is old information. The question established that we are talking about Anna and what she ate. The word “oatmeal” is the new information—the focus. It’s the crucial piece of the puzzle that the listener was waiting for. Notice how English naturally places this new information at the end of the sentence. This “old-before-new” principle is a fundamental tendency in many of the world’s languages.

Shaping the Flow: Word Order as Your Guide

While the old-before-new structure is the default, skilled communicators manipulate word order to shift emphasis and direct the listener’s attention. Changing the syntax isn’t just a stylistic quirk; it’s a powerful tool for reshaping the information structure of a sentence.

Consider the sentence: The dog chased the squirrel up the tree.

In its neutral form, “The dog” is the topic. We’re talking about the dog, and the new information is what it did. But what if the context is different? What if we were already talking about the squirrel?

Context: “I saw a terrified squirrel run for its life. I wondered what was after it.”
Answer: “The dog chased the squirrel up the tree.”

Here, even though the word order is the same, the focus (marked by spoken stress) shifts to “The dog.” The squirrel is now old information. But we can make this even clearer with syntax. We could use the passive voice:

Answer: “The squirrel was chased up the tree by the dog.”

This construction deliberately makes “the squirrel” the grammatical subject and topic of the sentence, aligning perfectly with the preceding context. The new, crucial information—the identity of the pursuer—is placed at the end, right where we expect the focus to be.

Another common technique is called a cleft sentence, which uses a construction like “It was…” or “What…” to explicitly isolate the new information:

Answer: “It was the dog that chased the squirrel up the tree.”

This structure powerfully spotlights “the dog”, leaving no doubt that this is the focus of the sentence. It’s like putting the new information under a linguistic microscope.

The Power of Emphasis: Stress and Intonation

In spoken language, our most potent tool for marking new information is prosody—the rhythm, pitch, and stress of our voice. The main stress in a sentence almost always falls on the focus. Take one sentence and see how changing the stress completely alters its meaning by shifting the focus.

Sentence: Sarah bought a new book yesterday.

• “SARAH bought a new book yesterday.” (…not Mark. The focus is on who did the buying.)
• “Sarah BOUGHT a new book yesterday.” (…she didn’t steal or borrow it. The focus is on the action.)
• “Sarah bought a NEW book yesterday.” (…not a used one. The focus is on the book’s condition.)
• “Sarah bought a new BOOK yesterday.” (…not a magazine. The focus is on the object.)
• “Sarah bought a new book YESTERDAY.” (…not last week. The focus is on the time.)

Each version answers a different implicit question. In writing, where we lack vocal cords, we have to simulate this stress using tools like italics, bolding, or, more elegantly, the syntactic structures we discussed earlier (like passivization and clefting). A good writer intuitively structures their sentences so the natural emphasis falls exactly where they intend the focus to be.

Why Does This Matter? From Clarity to Persuasion

Understanding information structure isn’t just an academic exercise. It’s fundamental to effective communication.

For Writers: It’s the key to creating prose that flows. When you consistently follow the old-before-new principle, you create a logical chain for your reader, where each sentence connects smoothly to the last. This is the secret behind writing that feels “easy to read.” Clunky, hard-to-follow writing often violates these principles, forcing the reader to work too hard to figure out what’s the topic and what’s the point.

For Language Learners: It demystifies why native speakers make certain grammatical choices. That “weird” word order you just heard probably wasn’t random; it was a deliberate choice to manage information flow based on the conversation’s context.

For Everyone: It’s a tool of emphasis and persuasion. By controlling what your audience perceives as the focus, you guide their attention. Journalists frame stories, lawyers build arguments, and marketers craft messages by carefully deciding what information to present as a given (the topic) and what to present as the key takeaway (the focus).

So, the next time you write an email, read a news article, or listen to a conversation, pay attention to the current. Notice how each sentence guides you from a familiar shore to a new one. You are witnessing the river of language in motion, skillfully navigated by the hidden, powerful principles of information structure.