Not all visual interfaces are graphical user interfaces

In the comments of some articles about natural user interfaces, one reads again and again that NUIs are only graphical user interfaces.
For simple definitions of a GUI, like the one from Wikipedia:

    "A graphical user interface is a software component that allows the user of a computer to interact with the machine using graphic symbols."

this also applies to natural user interfaces, since all visual interfaces are graphical in nature.
However, since a graphical user interface is more than just pictorial symbols, a more IT-specific definition must be used for delimitation:

    “The graphical user interface (GUI) is the name given to the graphical user interface that makes it easier to operate the computer. … Graphical user interfaces are clearly structured and, depending on the user program, include several functional areas, such as the menu bar, toolbar, function bar, status bar, task bar and scroll bars. These bars contain information, commands or graphic symbols that can be called up with a click of the mouse. ... "

Based on this definition from you can already see the first differences between GUI and NUI. Although many natural surfaces also have menu bars or corresponding alternatives to menu navigation, other elements are usually dispensed with.
According to Prof. Wolfgang Hensler, this may be due to the fact that most displays of devices with natural input options are relatively small, but also to the fact that NUIs are limited to the essentials so that the user can get a quick overview of the relevant screen contents can provide. Contents such as menus and settings only appear on the screen when they are relevant for the user, which in most cases only applies when the user calls up the menu.

In addition, every object, whether word or symbol, has its own context-dependent functions that can be called up with a click. Instead of selecting lines with the mouse in a writing program and pressing the button for "bold" in the toolbar, the user selects the corresponding text in a NUI application and is automatically shown what options he has to edit the text.
With devices with natural user interfaces, the user does not have to deal with nested menus or unknown ones
Annoying keyboard shortcuts.
Another difference to graphical user interfaces, which every user will notice very quickly during operation, is the intuitive input methods of devices with natural user interfaces.
Where the user previously had to operate keys, buttons or computer mice, speech, touch or body movements are now being used as control functions. The user can thus interact directly with the elements on the screen without the need for an additional device such as the mouse. Thus, a seamless interaction between humans and computers was created, through which virtual objects can be handled in a realistic manner.
Thus, for example, with a photo application on a multi-touch device, the virtual image can be handled as if it were directly on the table at home, only that the digital technology provides more options than just being able to rotate it .
However, the differences between GUI and NUI do not stop with display and control. In addition to the obvious aspects that the user recognizes directly, there are programming and social aspects that are not immediately recognizable for every user.
Programming aspects
Apart from the fact that one or more simultaneous touch events are not used on the programming level, various aspects must be taken into account when developing NUI applications.
On the one hand, the mouse pointer is missing in natural systems. This means that hovering or mouseover effects are no longer possible. These events, which are triggered as soon as the user moves his mouse cursor over an object, are mostly used in GUI applications to display additional information, such as the description of an image in an info box.
However, the absence of the mouse pointer also has other effects on the user interface. Touch surfaces that can be controlled by finger input must therefore have control elements that are adapted to the size of the fingertip. The pixel-precise operation, as it is possible with a mouse pointer, is no longer possible with natural user interfaces. Experts advise designing buttons for NUI applications with touch input accordingly.
For small screens, such as that of a smartphone, a minimum size of 5mm x 5mm is recommended for a button, for larger displays at least 1cm x 1cm.

    "Specifically, this means that the size of the interaction elements does not have to be based on the cursor, but on the finger.",

says Prof. Wolfgang Hensler.
Social aspects
People who use devices with natural user interfaces behave differently from a social point of view than people who use conventional computers with a graphical user interface.
This is due, among other things, to the multi-user capability. While only one person can actively work on normal computers at a time, NUI devices allow cooperative collaboration on one device.
Microsoft's chief designer August de los Reyes says:

    “If you put the headphones on your MP3 player in your ears, or if you are in a meeting and the participants suddenly take out their laptops and set them up, this creates barriers between people.

    However, when people position themselves around a multi-touch table like the Microsoft Surface, this barrier disappears.

    In this case, the technology takes a back seat and the interpersonal relationships of the users are strengthened through the mutual interaction. "


But such statements can not only be made in relation to the work environment. There are also examples in the public sector in which barriers, such as inhibitions regarding the use of NUI devices or speaking to strangers, dissolve.
James Hammond, chief analyst at Forrester Research, Inc. in Cambridge, described in a blog entry his experiences that he had gathered on a business trip at the airport.
On his way from a flight to the American Airlines Lounge, he came across a multi-touch wall and watched the visitors fiddling with it.

    “I'm sure you know that the average consumer is afraid of computers ... that's why it was so fascinating for me to watch people how they used the device without training or familiarity with the interface control. (Note: I mean the multi-touch wall.)… In a very short time, many visitors were playing with the screen, opening news tickers and other information and moving them around on the screen - and I'm very sure that it is people weren't IT professionals.

    The social interaction wasn't just on the screen. While two or three people were working on their little spot, I noticed that they kept looking at what the people around them were doing. Shortly afterwards, these conversations led to the experiences they had just gathered. Thus, the social interaction, which is otherwise carried out on the Internet between anonymous people, moved away from the actual device and into reality. "

The intuitive and natural operation of the multi-touch wall mentioned in Hammond's article reduced the inhibition threshold for trying out the device. In addition, it can be seen from the text that the control is easy to learn even for users with no computer experience and does not require any instruction.
In addition, social interaction with strangers would not have taken place in this case if it had not been a multi-touch wall, but a normal information terminal with keyboard and mouse.
This difference in social behavior clearly shows the positive aspect that a device with a natural user interface has in contrast to conventional computers with a graphical user interface.

Upcoming blog posts
Making The Game - Part 9: Advantages of natural input options based on practical examples
Making The Game - Part 10: Game Concept


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