Jakob Nielsen is a usability pioneer and researcher who established the "discount usability engineering" movement for fast, efficient improvements to user interfaces. He invented several usability methods, most notably heuristic evaluation. Nielsen co-founded the UX research firm Nielsen Norman Group with Don Norman, and holds numerous patents on making the Internet easier to use.

Jakob Nielsen

The Nielsen Norman Group (NN/g) is a user experience (UX) research and consulting firm. Co-founded by Don Norman and Jakob Nielsen, the firm's focus is to help designers and organizations create human-centered products and digital interactions, pioneering usability engineering methods.

Rutgers University

Google

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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