When you want to convey something to someone, you either speak or write. However we use input means, or methods, to convey our intentions to inanimate systems. In our daily life, various systems exist around us equipped with different input means. For example: switches that turn on lights, buttons for opening and closing elevator doors and moving up and down, sliders for igniting gas stoves and adjusting the heat, and so on.
Digital devices such as smartphones and PCs are very complex, so such operating systems such as Windows, iOS or Android are design to help user to do various things using a very small number of input methods. Even so, there are at least three variations of input methods that can be broadly categorised. If the input method changes, the appropriate interface design will also change. If you understand the characteristics of each input method, you should consider the according design approach.
Three means of input (operation method)
Apart from voice input, there are only three main types of input means (operation methods) that are used on a daily basis. And the UI design of the screen changes greatly depending on what the input method is.
Pointing
The first method is to operate by moving the cursor on the screen using computer mouse or trackpad. In addition to that, there are variations of pointing devices such as trackpads and trackballs.
Direct contact
The second method is to operate by touching the screen through a touch panel (touchscreen) such as a smartphone or tablet. Basically, you use your finger to operate, but sometimes you can use a touch pen instead. This is a relatively common operation method that can be seen in everyday life, such as ticketing machines and drink vending machines.
Focus
The third method is to operate by moving the focus on the screen, such as a TV remote control or game controller (game pad). They are also used in unexpected places around us, such as car navigation systems.
Pointing: Mouse/Trackpad
Mouse and trackpad are representative of pointing means of input. There are several other types, such as the trackpoint (which comes with Lenovo's ThinkPad, etc.) and the trackball (which rotates a sphere to control the cursor, however it is already outdated tech that was replaced by laser pointing). Also known as a "pointing device". These devices indirectly manipulate the "cursor" on the screen.
The advantage of these pointing devices is that they are suitable for detailed operations. Therefore, using a PC equipped with a mouse or trackpad, there is no problem interacting with its multifunctional interface design that assumes detailed operations, such as clicking small buttons or scrolling using a wheel on a mouse or using two-finger scrolling on a trackpad. Therefore, it is also suitable for designs that involve long vertical scrolling.
Direct contact: Touch Panels and Touchscreens
Smartphones and tablets are operated by touching the “touch panel”, also called touchscreen, with a finger. You can also operate with an alternative tool such as a touch pen instead of your finger. In either case, the touch panel is both an input device that accepts operations and an output device that displays the results at the same time. These devices are characterised by being operated by touching the screen directly.
Direct contact means that an object that can be touched must have a certain size. In addition, since the screen serves both as input (operation reception) and output (screen display), the overall design is unavoidably using large elements to fit the finger size. It is not very suitable for detailed operations. Although it is a good contrast with the previous pointing operation. In addition, hover feature available suing pointing devices isn't directly available on touchscreens where long touch tends to replace such feature. It is important to remember that our fingers aren't transparent, so when we want highlight something with the long touch, the highlighted object should have appear outside of touching area or at least have large enough area to be easily spotted under the finger.
On the other hand, it has the advantage of having unique touch panel operation methods such as swiping and pinching. A touch panel that moves when you trace it with your finger is much more straightforward than other operation methods (mouse, gamepads, etc.), so it can be said that it is suitable for children who have difficulty understanding indirect operations.