In usability testing, I see a lot of features, insights and apps that frustrate people. One particularly frustrating widget is the cascading menu when there’s a complex menu on screen with lots of categories that have to be precisely hovered over, people have trouble.
There’s a law of human computer interaction that explains some of this frustration. It’s not the fault of any individual user. It’s a fact that cascading menus are tricky for all of us. The steering law tells us why the steering law, a.k.a. the ecocide law, is a predictive model of movement. It predicts how quickly someone can steer appointing a device such as a mouse through a two dimensional tunnel on a screen. Here’s the equation. The most important variables are the time to travel through the tunnel and the width of that tunnel. It takes us more time to move a pointer or a mouse through a narrow tunnel. When we use our arms, there’s a natural curve. Moving in a precisely straight line is hard to see what happens when I try to draw a perfectly straight line. The steering Lau predicts that when we have to move precisely if we have to move through a complex menu where each individual tunnel is narrow, it takes us more time. If we try to move too quickly, we’ll be less accurate. So what does this law mean practically for us as we’re designing interfaces whenever possible, ad space around items in a menu? Tiny items on a menu mean that people have to navigate through narrow tunnels, which are difficult to use quickly and precisely if you’re designing a menu with multiple categories that open on hover, introduce a small delay before opening up that category. This delay helps make sure that the action to open up a menu category was in fact deliberate.
Keep laws of human computer interaction in mind when designing interfaces. Remembering these universal laws like the steering law can help you avoid creating products that frustrate the people who use them.