Usability Evaluation and Prototype Fidelity

One question that continues to be asked is how high does the fidelity level of a prototype need to be in order for the prototype to be useful in usability testing?

A study by Catani and Biers investigated the effect of prototype fidelity on the information obtained from a performance test. They had three levels of prototypes:

• Paper – low fidelity
• Screen shots – medium fidelity
• Interactive Visual Basic – high fidelity

Thirty university students performed four typical library search tasks using one of the three prototypes. A total of 99 usability problems were uncovered. The mean number of total problems encountered was:

• Low fidelity – 24.8
• Medium fidelity – 29.4
• High fidelity – 28.0

There were no significant differences in the number and severity of problems identified, and there was a high degree of commonality in the specific problems uncovered by users using the three prototypes.

These results seem to support the contention that one can extract as much information from a usability test using low-fidelity (paper) prototypes as from one using higher fidelity prototypes.

Usability Evaluation and Prototype Fidelity: Users and Usability Professionals, Catani, M.B. and Biers, D.W., Proceedings of the Human Factors and Ergonomics Society 42nd Annual Meeting, 1331-1336, (1998).