What Is Physical Interaction?

Posted on
intro to pcomp itpnyu

What is physical interaction?

A physical interaction is an agent’s use of controlled mechanical movement to change the state of another agent.

What makes for a good physical-digital interaction?

The quality of feedback is the most important element in good physical interaction. Without any feedback, a user has no idea what effect their interaction has.

A good physical interaction has clear cause and effect. The human brain is quite good at identifying patterns and relationships between disparate senses. A few key aspects of feedback affect how quickly a causal relationship is reinforced in the user.


Lower latency is better. If there is too long of a lag, the causal relationship between input and effect becomes ambiguous. High quality interactions have very low latency and feel immediate.


Mappings between input, effects, and feedback should be clear and intuitive. Binary inputs should have binary effects and feedback. Continuous inputs should have continuous feedback. Don’t forget that humans perceive the strength of feedback in a non-linear manner. Wikipedia, Stevens’ power law


Effect and feedback must be consistent for a given input.

Dynamic Range

High dynamic range adds clarity to the relationship. Without enough dynamic range, users face uncertainty and doubt when interpreting feedback. Having multiple sources of feedback add to dynamic range and help address accessibility issues.

Examples of good, non-interactive digital technology

  • wristwatch
  • basic cellphone
  • digital piano
  • basic activity tracker
  • weight scale