Properly used affordance beats any other design solution
Read time: 2 min
When it comes to solving for problems use design, not policy as the rule enforcer.
What is it?
This is a rolling computer cabinet. Notice anything odd about it? You may notice that the top of the cabinet is slanted forward.
Why is it good?
Why would the cabinet designer do that? Easy. There is a safety regulation that nothing should be stacked on top of rolling cabinets. It's a falling hazard for any one near the cabinet.
So what makes this so good? Naturally, it would be impossible to put anything on top of this cabinet. Which effectively accomplishes its goal. But the effects are even greater that that.
Ask yourself how safety policies like this are usually enforced. A sign posted on it right? Something like "DO NOT STACK ANYTHING ON THIS CABINET!" And how often are these types of signs ignored? Quite often. The real beauty of this design is that it completely eliminates the need for a sign or any enforcement at all.
THE BOTTOM LINE:
In all cases possible, don't rely on warning signs, dialogue boxes, or tooltips. Always design with the intent that the user cannot possibly get it wrong.
What principle is at work here?
This principle is known as an affordance. "The term affordance refers to the relationship between a physical object and a person (or for that matter, any interacting agent, whether animal or human, or even machines and robots). An affordance is a relationship between the properties of an object and the capabilities of the agent that determine just how the object could possibly be used." (The Design of Everyday Things, Don Norman, Basic Books, 2013)
Basically, an affordance is something that an object or interface allows a person to physically do. Here the cabinet restricts a person from placing something on top of it. In this case it's known as an anti-affordance., ie it doesn't allow something to happen. Keep an eye out for where you can use affordances and anti-affordances in your design work.