Preface

This book establishes a doctrine of Human-Centered Systems Engineering for the design, governance, and evolution of digital systems.

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How to read this book: This is written as a field manual, not an essay—terse, absolute, and command-form by design. The register is deliberate: it is the doctrine language of the U.S. Army, where I served, carried into the discipline of human-centered systems.

▶ “Directives are written to be met, not debated.“ ▶ “A standard you can defer is not a standard.”

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The purpose of the book is to codify enforceable standards that can be consistently applied, tested, and upheld across teams and systems—serving, for now, as a scaffold for best practices rather than a showcase of their practical application, which is reserved for future work.

This edition serves three functions:

Defines non-negotiable, human-centered principles that must guide digital system behavior.
Provides operational directives for translating those principles into product requirements and engineering decisions.
Creates a shared organizational framework for evaluating, auditing, and evolving UX and AI-mediated systems.

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“Those who are in love with practice without knowledge are like the sailor who gets into a ship without rudder or compass and who never can be certain whither he is going. Practice must always be founded on sound theory.”

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Leonardo da Vinci. From “The Notebooks of Leonardo Da Vinci”. I. Prolegomena and General Introduction to the Book on Painting (between 1480 and 1519).

1. Human Cognition & Behavior

▶ How humans perceive, think, remember, and decide during interaction with the system. ▶ These govern whether the interface can be understood at all.

Mission statement

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Ensure systems respect the limits and strengths of human perception, attention, memory, and decision-making so interfaces can be understood and used with confidence.

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