Jakob Nielsen, Ph.D., is a User Advocate and principal of the Nielsen Norman Group which he co-founded with Dr. Donald A. Norman (former VP of research at Apple Computer). Dr. Nielsen established the "discount usability engineering" movement for fast and cheap improvements of user interfaces and has invented several usability methods, including heuristic evaluation. He holds 79 United States patents, mainly on ways of making the Internet easier to use.

Jakob Nielsen

The company's vision is to help designers and other companies move toward more human-centered products and internet interactions, and are pioneers in the field of usability.

Rutgers University

Don Norman is the director of the newly established (2014) Design Lab at the University of California, Co-founder of the Nielsen Norman group and Honorary Professor at Tongji University (Shanghai) in their College of Design and Innovation. The term user-centered design came from him in his book The Design of Everyday Things (1988). It marked a shift from the previous term “user centered system design” where instead of focusing on the system itself and the aesthetics of the interface, Norman concentrated on user needs.

Don Norman

Nielsen Norman Group

Don Norman proposes the emotional system consists of three different, yet interconnected levels, each of which influences our experience of the world in a particular way. The three levels are visceral, behavioral, and reflective. 

(1)The visceral level is responsible for the ingrained, automatic and almost animalistic qualities of human emotion, which are almost entirely out of our control. 
(2)The behavioral level refers to the controlled aspects of human action, where we unconsciously analyze a situation so as to develop goal-directed strategies most likely to prove effective in the shortest time, or with the fewest actions, possible. 
(3)The reflective level is, as Don Norman states, "...the home of reflection, of conscious thought, of learning of new concepts and generalisations about the world". 

These three levels, while classified as separate dimensions of the emotional system, are linked and influence one another to create our overall emotional experience of the world.

Norman's Three Levels of Design

Flat design is a minimalist style of design.  It was created as a response to skeumorphism's realism.  Flat design creates websites that are cleaner and easier to navigate, as well as a more modern look with its grid-based layouts and bold typography, and can also lead to better visitor engagement.  However, one issue with flat design, according to the Nielsen Norman Group, is that the flat design reduced click confidence in users, meaning that the user's understanding of what was clickable and not decreased.

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