
Emotional responses elicited are difficult to measure because their nature is subtle (low intensity) and often mixed (more than one emotional response at the same time). However, scientific research at the Technical University of Delft by Dr. Pieter Desmet has resulted in an instrument, PrEmo, to measure emotions. Since then, PrEmo has been further developed by SusaGroup and TUDelft, resulting in a new and improved interface and character.

Instead of relying on the use of words, respondents can report their emotions with the use of expressive cartoon animations. In the instrument, each of the 12 measured emotions is portrayed by an animation of dynamic facial, bodily, and vocal expressions. PrEmo can be used in internet surveys, formal interviews, and in qualitative interviews.
In a review of Pieter Desmet's dissertation, Donald Norman has given some comments about PrEmo: