radial menus and fitts’s law
inspired by the nulooq, a little rant about radial (or sliced-cake) menus.
radial menus have always been a great way to navigate on screen, but i think ‘fear of the new’ prevents companies from implementing then more often. some observations and guidelines:
• radial menus can (if the number of items contained in them isn’t much higher than 10) be operated a more efficiently than linear menus (palettes) because directions are easier to remember and reproduce than distances: moving the input device in a direction and clicking vs locating the palette moving the cursor slowing down, aiming then clicking.
• radial menus can be designed to take advantage of fitts’s law*, making one or two edges of the button unlimitedly ‘long’. alias is using this in maya’s implementation: the idea is that you can overshoot the slice of the cake/button and the selection is still valid, because it’s the biggest slice of cake in the universe.
• radial menus tend to be implemented to appear on keystrokes, near or underneath the users cursor which makes travelling distances unnecessary, resulting in faster operation. depending on implementation they can be navigated without looking at the screen after the user is familiar with the directions and tools.
• since radial menus are often only visible when invoked they don’t cover up the working document and give you more screen real estate. on the down side the learning curve is higher because they aren’t always visible.
*fitts’s law (the time to acquire a target is a function of the distance to and size of the target) dictates that a button is a lot more useful when it borders to one or two sides of the screen because you can slam your mouse against the side of the screen (the target area can be considered infinitely long) without having to be afraid to miss the menu. this is why the screen corners are so attractive for menus because they easily ‘trap’ your cursor. a good example is the apple menu, the windows start button doesn’t take advantage of fitts’s law, because it has ‘dead’, i.e. non-clickable frame around it.
