Exploring Qualitative Displays and Interfaces

Much of how we construct meaning in the real world is qualitative rather than quantitative. We think and act in response to, and in dialogue with, qualities of phenomena, and relationships between them. Yet, quantification has become a default mode for information display, and for interfaces supporting decision-making and behaviour change. There are more opportunities within HCI for qualitative displays and interfaces, for information presentation, and an aid to help people explore their own thinking and relationships with ideas. Here we attempt one dimension of a tentative classification to support projects exploring opportunities for qualitative displays within design.


Introduction
Outside of the digital, we largely live and think and act and feel in response to, and in dialogue with, the perceived qualities of people, things and phenomena, and the relationships between them, rather than their number. Much of our experience of-and meaningmaking in-the real world is qualitative rather than quantitative. How friendly was she? How tired do I feel right now? Who's the tallest in the group? How windy is it out there? Which route shall we take to work? How was your meal? Which apple looks tastier? Which piece of music best suits the mood? Do I need to use the bathroom? Particularly rarely do we deal with quantities in relation to abstract concepts-two coffees, half a biscuit, three children, but rarely 0.5 loves or 6.8 sadnesses. And yet, quantification has become the default mode of interaction with technology, of display of information, and of interfaces which aim to support decision-making and behaviour change in everyday life [27]. We need not elaborate here the phenomena of the quantified self [36,42] and personal informatics more widely [24,12], except to note the prevalence of numerical approaches ( Figure 1) and the relative unusualness of non-numerical, pattern-based forms ( Figure 2). But what might we be missing through this focus on quantification? It seems as though there might be opportunities for HCI to explore forms of qualitative display and interface, as an approach to information presentation and interaction, as an aid to help people explore their own and each other's thinking, and specifically to help people understand their relationships and agency with systems. In this article, we discuss qualitative displays and interfaces, and attempt one dimension of a tentative classification supporting design projects exploring this space.

What could qualitative displays and interfaces be?
Here we define a qualitative display as being a way in which information is presented primarily through representing qualities of phenomena; a qualitative interface enables people to interact with a system through responding to or creating these qualities. 'Displays' are not necessarily solely visual-obvious to say, perhaps, but not always made explicit. Before exploring some examples, we will look at some theoretical issues. The terms 'qualitative interface' or 'qualitative display' are not commonly used outside of some introductory human factors textbooks, but forms of interface along these lines are found in lots of projects at CHI, TEI, DIS, Ubicomp and other venues, without authors explicitly drawing our attention to the concept-it is perhaps just too obvious and too broad to merit specific comment in HCI and interaction design research. But, assuming the idea does have value, what are some characteristics?
A human face is a qualitative interface, perhaps the earliest we encounter [e.g. 40] along with the voice. We learn to read and interpret emotions in others' expressions, to recognize commonalities and differences across people, to make inferences about internal and external factors affecting the person, and monitor the effects we or others are having on that person. We understand that the face and voice and our ability to read them are abstractions, interpretations, not perfect knowledge, but a model which enables us to make decisions in conjunction with our reading of our own emotions. In a sense, the whole world, as we perceive it, is a very complex qualitative interface. The most accurate model of a phenomenon is the phenomenon itself, but it is only useful to us to the extent we can understand what we are observing, detect the patterns we need to, and recognize that we are constructing the 'reality' we perceive. We are always creating a model [14] and that model is necessarily not reality itself; all displays of information    [32], drawing on Peirceian semiology, are relevant here, addressing the "causal distance" between the phenomenon and how it is displayed. One advantage of interfaces seeking to provide a qualitative display is that they have the potential to enable the preservation of at least some of the complexity of real phenomena-representing complexity without attenuating variety [2]-even if we do not pay attention to it until we actually need to, in much the same way as certain phenomena in the real world become salient only when we need to deal with them. Looking out of the window or opening the door to see and feel and hear what the weather is like outside presents us with complex phenomena, but we are able to interpret what actions we need to take, in a more experientially salient way than looking at some numbers on a weather app. The feel of the wind on our skin, or watching the wind affect the environment, gives us a better sense of whether we need a scarf or coat than knowing the quantitative value of the wind speed and direction (Figures 3, 4 and 5). We can see, hear and feel not just wind speed and direction, but other qualities of it-is it continuous? in short gusts? damp, dry? Qualitative displays could enable us to learn to recognize patterns in the world (and in data sets), and the characteristics of state changes, similarly to benefits identified in sonification research [35]. We should consider that 'qualitative' does not simply imply the absence of numbers. The examples we use in this paper might involve elements that could easily be quantified (rain drops, ink in a pen) but are given meaning through their display in a way that emphasises a quality or characteristic of the phenomenon. We recognise that this is potentially an ambiguous area, and are open to evolving the concept.
A spectrum of one dimension of qualitative displays: directness of connection Table 1 shows a tentative spectrum of one dimension of qualitative displays, relating phenomena to the display in terms of how directly they are connected. Levels 0-1 involve direct use of a real-world phenomenon in the display; from about Level 2 up to Level 5, they involve increasing degrees of translation or transduction of the phenomena. This parallels ideas in indexical visualisation [32] and embedded data representation [41] [19] offers a huge set of projects, many of which provide qualitative interfaces for data or system interaction (usually at Levels 4-5; Table 1).  The pattern of raindrops hitting a translucent umbrellafrequency, coverage, and sound-directly creates a 'rain display' for the user, providing insight into the current state and enabling decisions about whether the umbrella is still needed; City lights create a display showing the shape of the city's districts and indicator of population density; Water trapped in a train carriage window moves as the train ac-/de-celerates, creating a dynamic display of the train's motion; A transparent pen is a physical progress bar for the amount of ink remaining-it could be quantified, but it is perhaps the quality of being not-yet-run-out which matters to the user. Level 1: A worn patch on a map accidentally provides a display of 'you are here'; Use marks [5] from previous users demonstrate how to use a swipe-card for entry to a building; A spoon worn through decades of use is an accidental display of the way in which it has been used [31]; Footprints in the snow 'accidentally' provide a display of previous walkers' paths. Level 2: 'This Color For Best Taste' label gives 'meaning' to the colour of a mango's skin for the consumer (Photo used with permission of Reddit user /u/cwm2355); Writing 'Clean Me' or other messages in dust on a car gives meaning to the dusty property; Admiral Robert Fitzroy's Storm Glass, as used on the voyage of the Beagle (1831-6), incorporates crystals whose changing appearance was believed to enable weather forecasting (Photo: ReneBNRW, Wikimedia Commons, public domain dedication); George Merryweather's Tempest Prognosticator (1851 [30]) incorporates "a jury of philosophical councillors", 12 leeches whose movement on detecting an approaching storm causes a bell to ring (Photo: Badobadop, Wikimedia Commons, CC-BY-SA).

A spectrum of qualitative displays
Relating phenomena to the display in terms of how directly they are connected: Level 0: The phenomenon itself 'creates' the display directly Level 1: The display is an 'accidental' sideeffect of the phenomenon Level 2: The side-effect is 'incorporated' into a display that gives it meaning Level 3: The display is a designed sideeffect of the phenomenon Level 4: Some minor processing of the phenomenon creates the display Level 5: Major processing of the phenomenon creates the display  [37], for example, a way of turning quantitative data into a form of qualitative presentation? Even with a quantitative display, how a person interprets it may have a qualitative dimension: Figure 8 shows an electricity monitor used by a study participant [28] who accidentally set it to display kg CO2/day equivalent; this "meant nothing" to her but she interpreted the display such that ">1" meant "expensive". 'Annotations' of values as users construct their own meaning [11] may fit here; the aim must, however, be to avoid the kind of reductive 'qualitative' nature of a limited set of labels [13]. Analogy and metaphor are important here, and the almost-forgotten field of Analogue Computing offers us an intriguing perspective. By "build[ing] models that created a mapping between two physical phenomena" [7], some analogue computers effectively operated as 'direct' displays of an analogue of the 'original' phenomenon-a kind of meta-level 2 type qualitative display, with devices such as the 1949 Phillips Machine [4] (Figure  9), which performed operations on flows of coloured water to model the economy of a country, enabling an interactive visualization of a system in operation as it operates (there are parallels with Bret Victor and Nicky Case's work on explorable explanations [38,8], and the development of visual programming languages).
Other areas of pertinent research and inspiration, are synaesthesia and mental imagery: sensory overlaps, fusions and mappings offer a fertile field for exploring qualitative displays of phenomena.

Conclusion: What use is all of this?
We are interested in using qualitative displays and interfaces for supporting decision-making, behaviour change and new practices through enabling new forms of understanding-as an aid to help people explore their own and each other's thinking, and specifically to help people understand their relationships and agency with the systems around them [26]. Projects using qualitative displays are unlikely simply to be dequantified 'conversion' of existing numerical displays; instead, the aim will be to make use of the approach to represent and translate phenomena appropriately, in ways which enable users to construct meaning and afford new ways of understanding, enabling nuance and avoiding reductiveness. The spectrum of the 'directness' dimension introduced here provides a possible starting point for this work, by giving a framework for analysing examples and suggesting ways of handling phenomena to be displayed, and is currently being used by the authors to brief an undergraduate design studio project on materialising environmental phenomena to reveal hidden relationships. We welcome the opportunity to learn from the CHI community to inform our future explorations of this area.