Affordance and Design


Spending 2 years using the train door on the left, getting off at my intended stop became an unconscious routine procedure for me. It never failed. Then on my first day visiting a new client, I travelled on a different line by the train in the middle. Guess what happened – I failed to open the door and missed my stop! Thanks to having read Don Norman’s book ‘The Design of Everyday Things’ I do not blame myself for being the idiot. Now this week, on yet another rail line, I came across the door control design on the right.

Finally, a designer who has got it right. The green light tells me when the door is ready to be opened. I cannot recall ever having had a need to use a door ‘close’ button. On the new train an activity sensor at floor level detects inactivity for 10 seconds, and then automatically closes the door. Bravo. It has only been 25 years in the making.

Affordance and Design
Don Norman’s ‘The Design of Everyday Things’

Perceptual psychologist James J. Gibson is said to first use the term ‘affordances’ in the 1970’s, to describe the actionable properties between an object and a user. Humans can only assess objects according to their perceptible properties. In his fantastic book ‘The Design of Everyday Things’ (1988, revised 2013), design usability guru Don Norman adopted Gibson’s term ‘affordances’ to mean a user’s determination of what to do with things. He sensibly says that designed objects must have “affordances to conform to users’ needs based on physical and perceptual capabilities, goals and past experiences”. In his book he identifies that good design will clearly indicate use and avoid inadvertent misuse.

Industry and design standards are often a means to define a set way, which can help reduce variability and confusion errors. The similarity between train door control buttons gives appearance of the existence of a design standard. Regrettably, such train door button standard does clearly omit to specify or guide how the buttons should be arranged relatively to each other. That is unfortunately a common problem with industry standards.

Affordance and Design
Placement of ‘power’ and ‘delete’ keys on different laptop PCs

Another example of poor affordance by design happened when I recently started to use a new laptop computer. The ‘power’ button on the new machine is in the relative same place as the ‘delete’ key on my previous machine. This has resulted in several annoying episodes of unintentionally putting the machine into sleep, and having to wait for a restart, when intending to delete a single character. It will take some time to fully retrain my automated brain, during which time I will likely continue to repeat the mistake. Considering that the QWERTY layout has become a standard, why can the rest of the keyboard layout not also become standard? Again, the answer lays in a problem with industry standards.

It would have saved me – and many thousands of other users – some real hassle if the designers of train door buttons and computer keyboard layouts had spend more time walking the Gemba in the users’ world. They just might have foreseen and prevented the use errors that I have made.

This post illustrates just 2 examples of poor affordance by design. Now try extrapolating this to the many thousands of new products that are developed every year. Our world could be so much more hassle-free and productive, if just all designers would take Don Norman’s book to heart.