Book Summary — The Design of Everyday Things by Donald Norman
When I was studying for a Master’s degree in Computer Science, I took a course on user interface design. One of the assigned readings was a book by Donald Norman who is a noted academic in the field of cognitive design, and usability engineering. The book “The Design of Everyday Things” is a bestseller that remains hugely influential in the world of design and it had a big influence on me as well.
The book was written originally published in 1988, well before the Internet became mainstream, but it’s amazing how relevant it still is. Donald Norman has a website, which uses the design principles in the book to make recommendations on usability for websites and mobile apps (See here and here for some good examples). In preparation for my transition into the role of product manager, I recently re-read the book and thought it might be useful to summarise the key ideas from the book.
Affordances and Signifiers
I have grouped the first two concepts together as they go hand in hand. According to the book “Affordances represent the possibilities in the world for how a user agent interacts with something.” For example a cup has a handle that is big enough for the human hand, it therefore affords gripping. However not all affordances are easily identifiable. A signifier is something that signals the presence of an affordance. For example on a clear glass door without a handle, it may not be apparent which end of the door is to be pushed. Therefore the label “PUSH” is a signifier that can be added to signals which end of the door is to be pushed. Signifiers are important as they indicate how the system is meant to be used.
Mappings
Mappings specify the relationship between two sets of elements e.g the relationship between a set of light switches and the actual lights. Some mappings feel natural (e.g. turning the steering wheel left on a car to go left) while others do not (e.g Light switches where it is impossible to figure out which switch controls which light without resorting to trial and error). Good design makes use of mapping that is intuitive and feels natural. This may be dependant on culture and prior conventions. A few years ago, Apple tried changing the default setting on its trackpads so that moving your fingers down resulted in the page being scrolled up rather than down. This change in mapping was frustrating to many users who had grown used to the opposite mapping and many changed the setting to revert back to the original mapping. However, it is quite possible that future generations who use this new setting from day one, find it intuitive as it mimics the behaviour of a touchscreen.
Constraints
Constraints limit the number of actions that can be performed on the system. Good design uses constraints guide the user to the appropriate action. E.g. the corner pieces on Jigsaw puzzles where its obvious that the piece will only fit in the corner or the web application that only forces you to select from appropriate options by disabling the invalid ones.
Feedback
Feedback refers to the way that the user knows that the system has received their request and is currently processing it. Good designs feature immediate feedback — delays are disconcerting to the user. For e.g a user typing on a computer that has a small lag between the pressing a key and the display of the character on the screen will often press the key twice and make other errors.
Conceptual Models
Also referred to as mental models, this refers to our understanding of how a system works. For example, the file system in our computers is visually represented by icons of folders, sub-folders and files. In reality, this is not an accurate representation of how files are actually stored in computers. However, this mental model of folders is very effective in helping us gain an understanding of how we should organise our files and folders. Good designs use conceptual models that help the user understand how to use the product.
Final Thoughts
UI/UX design is a key part of a product manager’s responsibilities. A badly designed interface will frustrate users and ruin an otherwise good product and hence it’s important to focus on this as well. Design can also create a competitive advantage for a product as Apple has demonstrated over the last decade. Creating good design is not merely about aesthetics, it’s also about understanding how people think (This book was originally called “The Psychology of Everyday Things”). In my opinion, this book is a must read for a product manager and is a great introduction into user centric design. If you prefer a more hands on learning approach, the author also teaches the material from the book in a course on Udacity. You can view several of his talks and seminars on YouTube.
