First Law of the Interface: The interface is the place of interaction
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What’s an interface? I’ve discovered that each definition of the interface hides a metaphor. In other words: the interface can be understood from different perspectives and analogies.
The interface as a surface
According to The Oxford English Dictionary an interface is “a surface between two portions of matter or space that have a common limit”. The term was introduced by J. T. Bottomley in Hydrostatics (1882) to identify a “separation surface” between two liquids. But the interface does not only separate: it allows certain elements (molecules, particles, etc.) to pass through it, like in osmosis.
The spread in the 1980s of personal computers with operative systems designed with the philosophy of WYSIWYG (What You See Is What You Get) expanded and upgraded the metaphor of the interface as a surface. These devices introduced a new way of exchanging information between the user and the digital machine based on graphic representations on the screen. From this perspective, the interface is like a skin that conveys instructions (affordances) that explain how to use the interface to the user.
The interface as an information interchange device
Half a century later, Bottomley computer scientists took the concept and used it to define a material device that allows the interchange of data between two systems, for example, the “interface between a computer and a printer” or a “USB interface”. In short: we do not only have an interface on the screen at front of our computer. Turn it around and look at the back: there are plenty of interfaces! Interfaces for connecting the printer, the mouse, the screen, an external disc, a camera, a smartphone, an Ethernet line or another computer. Many of these connections today have become wireless interfaces.
The interface as a conversation
Some researchers and designers consider that the interface is a conversation between the user and a technical device. This idea was especially important in the 1950s, when computer scientists started developing the first Artificial Intelligence programs. As the Turing Test proclaimed, an ‘intelligent machine’ should at least speak and understand human language (Turing, 1950).
From a semiotic perspective the conversation is not between the machine and the human but between the designer and the user, like in a text-mediated interchange between an author and the reader. When we read a book we establish a ‘conversation’ with the author of the text: the author puts something inside the text and we, the readers, collaborate in the construction of the meaning of the work (Eco, 1979). Similarly, when we interact with a computer we establish an asynchronous and remote interchange with the creator of the interface.
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The interface as an instrument
Leading human-computer interaction experts like Don Norman (1990a) adopted a definition that considers the interface as an instrument, a tool or a prosthesis that allows the subject to manipulate a technical device and accomplish a task. According to Norman the best interface disappears when we are using it: “The real problem with the interface is that it is an interface. Interfaces get in the way. I don’t want to focus my energies on an interface. I want to focus on the job” (Norman, 1990b).
The interface as a tool is the mother of all the metaphors, the first conception that a user frequently formulates in front of any technological device. To say that the interface is a tool is also a basic and primary response of the interface analyst. I wrote The Laws of the Interface to change this vision of the interaction process (Second Law). I believe that the interface is something more than a simple tool or instrument.
The interface as a place
The arrival of the World Wide Web and the propagation of videogames in the 1990s has reinforced this metaphor. For new generations social media are a place to meet people and interchange information of any kind. The metaphor is so strong that it’s very difficult to avoid using it in everyday conversations.
From a scientific perspective, the interface as a place where different actors interact and maintain relationships is one of the most useful conceptions for developing a Theory of the Interface.
Towards an expanded definition of the /interface/
In short: What’s an interface? A univocal definition of interface does not exist. At this point the interface means so many things that we can make it say whatever we want. Its semantic existence is so weak, fluctuating and malleable that we can only metaphorize it: the interface as a membrane, the interface as a communication device, the interface as an instrument, the interface as a conversation, the interface as a place. Each of these metaphors illuminates certain aspects of the interface, privileging some of its properties but at the same time hiding others.
My experience in this field suggests to me that the ‘interface as a place’ is possibly the best metaphor, the one that reveals the most pertinent traits of the interaction. This metaphor also contains the rest of the metaphors: in a place we can manipulate instruments, connect devices between them, perceive information from the surfaces and establish conversations. In this context, the interface is the place where human (individual, institutions) and technological actors interact and maintain different kinds of relationships. Or, in a few words, the interface is the place where things happen.
The metaphor also works like a perception and interpretation modeler agent that guides the interface designer’s actions. It is not the same to design interfaces in the belief that they are docile instruments in the hands of the user as it is to design them in the belief that they are conversational interchanges. Likewise, it is not the same to study interfaces as if they were a membrane as it is to study them as a space in which semiotic and cognitive processes take place.
We could spend an entire lifetime looking for a good definition of /interface/. And while we design, use, reflect, define, classify and write about them, interfaces evolve, contaminate and live an independent existence far away from our theoretical ruminations.
Note: This text is a synthesis of my book Las Leyes de la Interfaz published by Gedisa in 2018.
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References
Bottomley, J. T. (1882). Hydrostatics. London: William Collins.
Turing, A. (1950). Computing Machinery and Intelligence, Mind LIX (236), pp. 433– 460.
Eco, U. (1979). The Role of the Reader: Explorations in the semiotics of texts. Bloomington, IN: University of Indiana Press.
Norman, D. (1990a). The Design of Everyday Things. New York, NY: Doubleday.
Norman, D. (1990b). ‘Why interfaces don’t work’. In: Laurel, B. (ed) The Art of Human-Computer Interface Design. Reading, MA: Addison-Wesley, p. 210.
Scolari, C.A. (2018). Las Leyes de la Interfaz. Diseño, ecología, evolución, tecnología. Barcelona: Gedisa.