Principle Four: Perceptible Information

The design communicates necessary information effectively to the user,
regardless of ambient conditions or the user's sensory abilities.

UD Example: "talking" thermometer with large numerals.

Principle Four: Perceptible Information Instruction is designed so that necessary information is communicated effectively to the user, regardless of ambient conditions or the user's sensory abilities.

UDI Example: book and CD formats for college textbook.