This structure is called "inverted" pyramid because it resembles an upside down pyramid, with the biggest, broadest part at the top tapering down to a narrowed point.

In a research paper context, this means:

Introduction:

Begin with the widest, most general overview of your topic. Provide broad context and background information that frames the subject. Include definitions of key terms, overall significance of the issues, etc.

Body Paragraphs:

Progressively narrow focus through each paragraph to build up to your thesis and core argument. Each body section provides additional details, evidence, and analysis that directly supports your paper's key claims.

Conclusion:

Wrap up by tapering back out slightly for the finishing point of the inverted pyramid. Remind readers of the most impactful takeaways related to your thesis statement. Explain significance of findings without introducing brand new content.

This inverted approach establishes wider framing and then zeros readers in on the crux of arguments for greatest clarity. It prevents lacking focus or overwhelming with too much granular data too soon. Following this classic structure allows research writing to feel more persuasive and concisely purpose-driven.