Overview

The best code in the world is useless if people can’t figure out how to use it. HCI is where Computer Science meets Psychology. It is the study of how to make computers intuitive, helpful, and invisible. It gave us the Mouse, the Touchscreen, and the “Undo” button.

Core Idea

The core idea is User-Centered Design. Don’t blame the user (“PEBKAC - Problem Exists Between Keyboard And Chair”). Blame the design. If the user makes a mistake, the interface is wrong.

Formal Definition

The study of the design and use of computer technology, focused on the interfaces between people and computers. Norman Doors: A door that you pull when it looks like you should push. A bad interface.

Intuition

  • CLI (Command Line): Powerful but hard. You have to memorize magic spells (ls -la).
  • GUI (Graphical User Interface): Metaphors. “Here is a file folder.” “Here is a trash can.” It uses your real-world knowledge to make the computer easy.

Examples

  • The Mouse: Invented by Doug Engelbart in 1968 (“The Mother of All Demos”). Before that, you only had a keyboard.
  • Multi-Touch: The iPhone. Pinch-to-zoom. It felt like magic because it mimicked manipulating physical photos.
  • Dark Patterns: The evil side of HCI. Designing interfaces to trick you. (e.g., The “Unsubscribe” button is tiny and grey, while the “Stay” button is huge and green).

Common Misconceptions

  • It’s just making things pretty: No, it’s about function. A pretty app that crashes or is confusing is bad HCI.
  • Accessibility is optional: Designing for the blind (Screen Readers) or motor-impaired makes the product better for everyone (Curb Cut Effect).
  • UX (User Experience): The whole journey. How you feel when using the product.
  • UI (User Interface): The buttons and pixels.
  • Affordance: A button should look clickable. A slider should look slideable.

Applications

  • Safety: Designing the interface for a nuclear power plant or an airplane cockpit. A bad design here causes disasters (Three Mile Island).

Criticism / Limitations

  • Addiction: We have become too good at HCI. We designed “Infinite Scroll” and “Pull-to-Refresh” (slot machine mechanic) to keep people addicted to their phones.

Further Reading

  • Norman, Don. The Design of Everyday Things. (The bible of HCI).
  • Krug, Steve. Don’t Make Me Think.