What is a Circle Menu?

We've all seen a lot of menus in our lives. Restaurant menus, a TV Guide movie listing or a clothes-rack at the mall. Menus also exist in the computer world. However, in Graphical User Interfaces the primary type of menus are the pull-down and tree menus, both of which are a variation on the same concept: a list. But as with many a paradigm in computer science, I believe that they should make way for a better menuing system: the Circle Menu.
Pull-down Menu
Tree Menu

        "So what's wrong with the normal menu's?", you ask, "Don't they do their job just fine?" Well, yes and no. Of course, list-based menus are a good idea. The fact that the menu items are arranged one below another, like text in a book, makes it easy to read through the entire menu while looking for what you want. However, once you've grown familiar with the menu, you already know where the options are so you shouldn't need to read them to get to what you want. Unfortunately this is not the case with list-based menus. You always have to scan through all the options as you move your mouse down to the option of your choice. If you didn't look then you'd most likely miss your selection and choose something completely different. Why? Because moving your hand a precise distance without looking is not a natural motion. We just don't do that in real life. So why are list-based menus set up like that? Simple, it's because they were created in the days when the keyboard was the primary tool to use with menus and it made a lot of sense to use the up and down keys to walk up and down a menu. Today the mouse has become our primary menu selection tool. But our menus haven't changed, forcing us into an unnatural and therefore imprecise hand motion. It would make a lot of sense if the user had to use a more natural gesture to make their mouse selection.
        Another problem is that in a list-based menu, the options on top are a lot closer to the mouse than the options on the bottom. This doesn't make much sense. It would make a lot more sense if all the menu options were the same distance away from the mouse.  The only way to fulfill the second requirement is to put the menu options in a circle around the mouse. This has the natural side-effect of fulfilling the first requirement: the motion needed to select the menu options is the movement of the hand in a given direction, which is much more precise than moving it a certain distance. Ok, ok, so it does make some sense but is it actually more usable?
        Lets run an experiment. Bring up a menu that you've used many times before. You know the menu, and you know what you want to find there. Can you make your selection without looking at the menu? Of course not. Unless you have perfect precision you'll never manage to move the mouse down the exactly correct distance and you'll probably misfire. But you can with a circular menu. If the menu options are all around the mouse, then all you have to remember is the direction in which the option of your choice lies. This is a more exact motion for you and unless there is over a dozen menu options, you have a wide margin of error. Furthermore, people can remember the motions they perform in a task, making it routine for them. One study in particular found a 15%-20% speed increase while using a pie menu (a type of circular menu) as compared to a standard linear menu[2]. That means that if you use circular menus, you can control your menus purely by hand, from memory and without moving your focus of attention from the task at hand.

Circle Menu

        So that's a Circle Menu. Kinda on the convenient side but not perfect because as you can see, the menu options are actually kind of small. So its pretty easy to miss them. So you still have to look up from your work and gently guide the cursor to the menu option of your choice. So what's the big benefit? Ah! But they don't just stay there. They're a lot smarter than that. If you move your mouse away from the menu center, the menu options closest to your mouse will move towards it while the options further away from the mouse will move away. Furthermore, the menu option closest to the mouse pointer will literally follow the pointer around. So if you're looking at the menu, you'll get intuitive visual cues regarding which option you're trying to select and if you're not looking, all you have to is point the mouse towards an option and it will come to you. And notice something else: the menu options only cover up as much space as they need. Whatever is not in the option rectangles, doesn't block your view. And finally, the little square in the middle. What's it for? Well, what if you enter a menu or a sub-menu and you decide that you don't really want to be there? Just click on the square and leave the menu. Pretty easy, huh.
        And that's it. Circle Menus are a great alternative to list-based menus for any menu that you expect to be using a lot. They're harder to read but easy to learn in the long run and after a while they become so automatic that you don't even notice them any more. And that's really the point of a user interface: to be the invisible hero, tying the human and the computer together without being noticed.

Circle Menu Central