Interaction design is design for human use. It involves answering three questions:


How do you Do?

One of the important choices for
"How do you do" is between

Handles are better for continuous control
(e.g. trombone slide, steering wheel)

Buttons are better for discrete control
(e.g. piano keyboard, ignition key)

Handles leave you in control
(e.g. volume control on TV).

Buttons are more likely to trigger something automatic
(e.g. opening an elevator door).

How do you feel?

One choice for "How do you feel?" is McLuhan's "hot" vs "cool".

Hot media like print are more authoritative and exact.

Cool media like cartoons and television are fuzzy and incomplete they invite more participation.

How do you know?

One choice for "How do you know?" is between MAPS and PATHS.

Paths are good for beginners; "just tell me step by step what to do."

Maps are good for understanding alternatives, they take longer to learn but are more robust.

Paths are good for training expert skill; they can be very efficient.

Here are two vending machines.
One presents a PATH-like interface.
One is more like a MAP.

Which do you prefer?

Which is better for the vendor?

Which is faster?

What are the failure and recovery possibilities?


What is a computer? Various metaphors have organized entire careers.

Such powerful metaphors are called "paradigms".
They motivate the central questions asked.
They help us understand the STYLE of interaction.
Understanding competing paradigms helps us understand what
various people consider a "good" interaction design.

Interaction Design Process


At least eight distinct phases can be identified in the interaction design process. They range from the concrete instance (path-like) to the general overview (map-like) and from invention to presentation.