Zijlstra's mental effort scale is an easy and quick to use scale that helps to determine how much (perceived) mental effort was required to complete a task; depending on the setting, product and task, and in combination with other measures, this will help in getting a clearer picture of the overall quality of a product or service - too much mental effort will be stressful, and scary, too little mental effort will be boring....
+ validated instrument; very sensitive; easy to use by participants
'+ used in different settings
needs to be used in combination with other tools to get a broader picture
T Meijman, F Zijlstra, M Kompier, H Mulders, 1986, The measurement of perceived effort, Ergonomics: Proceedings of the Ergonomics Society's, Taylor & Francis
References describing the method