The Uncertainty Principle states that the act of measuring a variable can affect the nature of the system enough that it alters the measurement in a way that makes the measurement invalid. This depends on how expensive and invasive it is to get the measurement. Using computer event logging as an example we can understand the principle. Creating log files that periodically record details about a computer’s performance will consume computer resources, which can degrade computer performance just by the virtue of recording this information. The level of invasiveness required to measure the performance will dictate how the overall system performance is taxed, for example checking a performance variable multiple times a second and recording that information to a file immediately uses more computer resources than checking every minute or hour. A system doing frequent lookups and writes will appear busier than usual and will result in performance metrics that inflate or deflate whatever variable was being measured.
William Lidwell, Kritina Holden and Jill Butler, Universal Principles of Design (USA: Rockport publishers, 2003), 244.
This principle can be applied to design in multiple ways. Designers should be careful to use minimally invasive measures, not only with technology but in social and behavioral ways. For example when interviewing people about their impressions with a product or service they should be careful how the questions are formed so that the participants are not put on the spot or pressured which can result in dishonest answers. This principle can be used to promote positive behaviors too, for example a common weight loss technique is to keep a diary of all the food one eats throughout the week. This awareness alone can trigger a self analysis and reflection that can lead a person to adjust their diet make healthier choices.
Original source image
William Lidwell, Kritina Holden and Jill Butler, Universal Principles of Design (USA: Rockport publishers, 2003), 245.
Real world image
Monitoring my Prius’s mpg metrics while I’m driving makes me more aware of how I handle the car and sometimes causes me to ease up on the gas pedal to conserve more gas.