In the middle of the 20th century, the idea of aesthetics was deployed in scientific contexts. Charles E. Osgood developed his semantic differential method in which he quantified the peoples' perceptions of artefacts. Some years later, in 1960, Professors Shigeru Mizuno and Yoji Akao developed an engineering approach in order to connect peoples' needs to product properties. This method was called quality function deployment (QFD). Another method, the Kano model, was developed in the field of quality in the early 1980s by Professor Noriaki Kano, of Tokyo University. Kano's model is used to establish the importance of individual product features for the customer's satisfaction and hence it creates the optimal requirement for process oriented product development activities. A pure marketing technique is conjoint analysis. Conjoint analysis estimates the relative importance of a product's attributes by analysing the consumer's overall judgment of a product or service. A more artistic method is called Semantic description of environments. It is mainly a tool for examining how a single person or a group of persons experience a certain (architectural) environment.