According to Shneiderman's definition, what became a cornerstone of modern interface design that guides user interaction with on-screen objects?

Answer

Direct manipulation.

Shneiderman emphasized direct manipulation as a guiding design principle, meaning users interact directly with objects on the screen rather than inputting abstract commands.

According to Shneiderman's definition, what became a cornerstone of modern interface design that guides user interaction with on-screen objects?
inventorhumancomputerinteraction