Emerging Approaches to Research and Design Practice Signifiers, Not Affordances Donald A. Norman Nielsen Norman Group and Northwestern University | [email protected] It’s time for a review. As times informative result of the behav- trail or trace of previous behav- and technologies change, as we ior of others. Let me illustrate. ior: desire lines, as these are have moved from individual to Suppose you are rushing to called in architecture and city References group, social, and even cultural catch a train. You know the planning—when the trails made computing, and as communica- train was scheduled to depart by people’s footsteps across tion technologies have become soon. You run across the city, fields indicates their desire for as important as computational run up the stairs in the train paved paths. ones, how well have our design station, and rush on to the I call any physically perceiv- principles kept up? platform. But there is no train. able cue a signifier, whether it is One of our fundamental Did you miss it, or perhaps it incidental or deliberate. A social principles is that of perceived simply has not arrived yet? How signifier is one that is either cre- affordances: how we know what can you tell? The state of the ated or interpreted by people or to do in novel situations. That’s platform serves as a signifier. society, signifying social activity fine for objects, but what about People milling about? The train or appropriate social behavior. situations? What about people, has not arrived. An empty plat- Thus, although there are many social groups, cultures? The form? Oops, you missed it. This possible signifiers of wind speed answer is the same, yet differ- is an example of an incidental, and direction, including flags, ent. Yes, there are still perceived accidental signifier. It isn’t com- the movement of grasses or tree affordances, constraints, and pletely reliable, working better leaves, or traveling debris, if conceptual models, but there’s in small towns with only occa- the signifier is a flag, it is also a more. There are trails. There sional trains than in crowded social signifier—people placed are behaviors. We know how to cities where many trains use the that flag in its location, presum- behave by watching the behav- same platforms, but that is the ably for a reason (which may ior of others, or if others are not nature of signifiers: often use- have nothing to do with provid- there, by the trails they have ful, but of mixed reliability. ing an indication of the wind). left behind. As we move from Social signifiers, such as the the world of stand-alone objects presence or absence of people on Signifiers, Not Affordances to social structures, complex, a train platform, painted lines The concept of “affordance” has intelligent products, and a heavy on the street, the trails that captured the imagination of dominance of services, then signal shortcuts through parks designers. The term was origi- new principles are needed. or across planted areas, are nally invented by the perceptual Powerful clues arise from examples of signaling systems. psychologist J. J. Gibson to refer what I call social signifiers. A Signals come in many forms, to a relationship: the actions “signifier” is some sort of indica- sometimes naturally evolved, possible by a specific agent on a tor, some signal in the physical sometimes conventions of cul- specific environment. To Gibson or social world that can be inter- ture. Cues carry evidence, some- affordances did not have to be preted meaningfully. Signifiers times completely unintentional, perceivable or even knowable— indicate critical information, as in the emptiness of the train they simply existed. When I November + December 2008 December + November even if the signifier itself is platform. A flag’s fluttering introduced the term into design an accidental byproduct of in the wind is a clue to wind in 1988 I was referring to per- the world. Social signifiers are direction and speed, usually ceivable affordances. Since then, those that are relevant to social unintentional, but nonetheless the term has been widely used usages. Some social indicators useful evidence to the observer. and misused. The result has interactions simply are the unintended but Sometimes the evidence is a been confusion and a gold mine 18 OPINION THE WAY I SEE IT for academic scholars, who get get through.” Electronic book to write learned articles about readers do not have the physi- the true meaning of the term. cal structure of paper books, so People need some way of unless the designer deliberately understanding the product or provides a cue, they need not service—some sign of what it convey any signal at all about is for, what is happening, and the amount of text remaining. what the alternative actions The traditional browser on the are. People search for clues, for computer screen provides a any sign that might help them deliberate social signifier, with cope and understand. It is the the position of the scrollbar sign that is important, anything showing how much more of that might signify meaningful the document remains and its information. Designers need length showing what propor- to provide these clues. Forget tion is visible at the moment. affordances: What people need, Hill, Hollan, Wroblewski, and and what design must provide, McCandless’s addition of usage are signifiers. Because most marks—edit wear and read of how they operate. We seek actions we do are social, the wear—is yet another clever way all possible cues to help in this most important class of these for designers to add signifiers enterprise, and in this way, we are social signifiers. to guide readers of electronic all act as detectives, search- We are all detectives search- documents [1]. ing for whatever guidance we ing for clues to enable us to The signifier is an impor- might find. If we are fortunate, function in this complex world. tant communication device to thoughtful designers provide the [1] Hill, W., J. D. Hollan, D. Wroblewski, and Whether it is flags waving in the the recipient, whether or not clues for us. Otherwise, we must T. McCandless. “Edit Wear and Read Wear: wind, the difference between communication was intended. use our creativity and imagina- Text and Hypertext.” empty or crowded train plat- From the purpose of surviving tion. (This is the premise behind Working paper. CHI’92, Monterey, Calif., 1992. forms, or the desire lines illus- in the world, it doesn’t matter Distributed Cognition [2].) trated by footprints in the fields, to an individual whether the Social signifiers replace affor- we search for significant signs useful signal was deliberate or dances, for they are broader and in the world that offer guidance. incidental: To the recipient, no richer, allowing for accidental In the social world comprising distinction is necessary. Why signifiers as well as deliberate people and technology, these should it matter whether the ones, and even for items that cues are social signifiers. flag was placed as a deliber- signify through their absence, [2] Hollan, J. D., E. Consider a bookmark, a ate clue to wind direction (at as the lack of crowds on a train Hutchins, and D. Kirsh. “Distributed Cognition: deliberately placed signifier of airports or on the masts of sail- platform. The perceivable part A New Foundation one’s place in a book. But the boats) or whether it was there as of an affordance is a signifier, for Human-Computer Interaction Research.” physical nature of books also an advertisement or symbol of and if deliberately placed by a ACM Transactions makes them an accidental social pride in one’s country (on public designer, it is a social signifier. on Human-Computer Interaction: Special signifier, for the placement of buildings): Once I interpret the Designers of the world: Forget Issue on Human- Computer Interaction in the bookmark tells the reader flag’s motion to indicate wind affordances. Provide signifiers. the New Millennium 7, how much of the story remains. direction, the flag’s intended no. 2 (2000): 174-196. <http://hci.ucsd.edu/ Most readers have learned to usage no longer matters. ABOUT THE AUTHOR Don Norman lab/hci_papers/JH1999- wears many hats, including cofounder of 2.pdf> use this accidental signifier to Whatever their nature, the Nielsen Norman group, professor at aid in their enjoyment of the planned or accidental, signifiers Northwestern University, and author. It should not come as a surprise to learn that reading. With few pages left, provide valuable cues as to the 2008 December + November we know the end is near. And if nature of the world and of social social signifiers play a major role in his new book, tentatively entitled Sociable Dezsign. the reading is torturous, as in activities. For us to function in He lives at jnd.org. a school assignment, one can this social, technological world, always console oneself by know- we need to develop internal DOI: 10.1145/1409040.1409044 ing “only a few more pages to models of what things mean, © 2008 ACM 1072-5220/08/1100 $5.00 interactions 19.