Perceived usability and system complexity

The study presented investigated the influence of system complexity and previous experience on the perception of usability. Each of 24 subjects used a standard (simple) and a feature-rich (complex) graphical information retrieval system to complete a total of 6 information searches. The subjects provided ratings of the ease of learning, using and understanding each system. These ratings were used to develop a scale metric of usability. The standard system had a significantly higher usability metric than the feature-rich system. Only the feature-rich system resulted in significant differences based on subjects' previous search related experience. The usability metric was significantly lower for the feature-rich system for subjects educated in library science compared to subjects without that educational background. There was a significant correlation between familiarity with mouse based interfaces and the ease with which subjects understood the feature-rich system. There was a significant negative relationship between prior experience with commercial online systems and the ease with which subjects learned the feature-rich system. It is concluded that perceptions of usability decrease as the complexity of the user interface increases and that prior experience with other systems increases this effect.