Jon Rogers and Rory Hamilton

Surfaces in Mind

Keywords: Design Research, Visual Perception, Form, Product Design, Interaction Design, Prototypes, Observational Prototyping

1.0 Abstract In this paper we will present concepts and practices from the ‘Art and Visual Perception’ research project on placing theories and examples of visual perception, particularly relating to motion and depth, into art and design practice and process. Fundamental to this program is the investigation of the relationship between physical and perceptual representation of surface. The implications for the design process is that if we can understand, through sketch, experimentation and prototype, how we perceive surface, texture, form, 2D and 3D, then we can develop new design methodologies. These new design techniques and tools and processes will enable scalable (the same processes functioning on a handheld surface that will also function on/as surfaces covering new buildings for example) designs that challenge existing perceptions of surface, texture, form, 2D and 3D.

2.0 Introduction The ‘Art and Visual Perception’ research project was initiated by the authors of this paper to investigate the role visual perception has in the making processes of art and design. The post 1990 computational boom saw new and exciting practices emerge in art and design, while simultaneously computational theories, methods and processes were leading advances in visual perception science. Computation provided a new working platform for cross discipline research where common ground could be reached and understood. Surfaces and surface effects became a focus for the Art and Visual research project, where computer screen became a surface for exploration and exploitation of visual perception.

Surfaces cover everything, and are made from everything. Surface is fundamental to design. Surfaces are defined by their physical properties, encompassing sight and touch. In this paper, it is the sight or appearance of surfaces that we will be exploring – in particular we are interested in providing illusory surfaces, through depth and motion, where the properties and materiality are defined, and embodied wholly in the mind. This is particularly important for design as it implies that new surfaces can be created on objects or in spaces that lack appealing, useful or meaningful qualities – for example mobile phone screens, dark corners and concrete jungles.

The format that this paper will take is to introduce some of the key general thinking behind visual perception research, and then to show through application how specific perceptual phenomena have been used in a variety of contexts and environments under the general research umbrella of using perception as a designer/artists tool.

This paper intends to provide relevant research methods, theory and practice to the general (EAD conference) theme of Design Research in addition to specific relation to several of the key themes, namely that of research through evolving design processes. We will show examples and application contexts that explore how we see surfaces based on the relationship between the physics and psychology of form.

3.0 Background The way we interpret our visual environment has been a subject of observation, comment and study for several thousand years – it would be fair to hypothesize that the way the world looks must have been a primal thought since human conscious awareness evolved, as represented in early cave drawings. Hypothesizing aside, it is well documented that the philosophical greats from Aristotle, to Wittgenstein , have all provided some observation or commentary on the way our minds interpret the physical world we exist in. For a review of the pre-empirical theories see Wade(1998).

From these early observations and cultivations of visual thinking, the Gestalt movement emerged in the early twentieth century (Gordon, 1989), where illusion and optical effects became a subject for experiential, rather than experimental, study. The Gestalt movement, while not adhering to the modern notion of empiricism, identified, categorised and documented axioms of perception that are an intrinsic component of today’s science, art and design communities. The idea behind Gestalt is simple: The whole is greater than the sum of its parts - yet this simplicity has created a foundation for modern art, design and the psychology education, research and practice. The key points to Gestalt theory are shown below (figure 1) and can be summarised as follows:

 Figure-ground separation: The ability of the observer to distinguish between foreground and background, or object from subject.

 Completing: The visual system’s processes of constructing a whole image from a broken, or noisy, image.

 Grouping: The natural grouping of objects into familiar structures.

Figure-Ground Completion Grouping

Figure 1: Examples of Gestalt

The main criticism of the Gestalt movement was the lack of experimental evidence as proof of beliefs – visual demonstration was used as an explanation, rather than data. On the other hand, empiricism, the application of scientific rhetoric, took the standpoint that perception was something more than the occurrence of a particular stimuli; that somehow other internal (mind) events and processes intervene between stimulation and experience. In order to discover the underlying mechanisms and processes, experimental methods drawn from physics and biology were employed. From empiricism came direct perception – optimised by Gibson (1986). In direct perception, the position is that the retina converts the optical world into electrical/neural signals which are filtered and interpreted to form some mental visual model. From direct perception, came constructivism – the concept that unconscious visual thinking creates a mental model for most of what we see. This model is then used by the visual brain to re-construct what is actually present in the real world. This theory accounts for the ability of the brain to complete partial or noisy signals (as shown in the Dalmatian contained in figure 1). Gregory (1997), discusses this in some detail, and is one of the leaders of this perceptual theory. The important concept of constructivism is that the mental model created is based on a combination of direct perceptual cues and more complex cognitive processes. Direct and constructivist theories can broadly describe and provide insight to, in the context of this paper, our experiences when viewing visual illusions. Psychology theories of perception are intertwined with neuro- physiological studies - for example, Hubel (1995) and Zeki (1993). An important technical consideration of perception research is the introduction of computational theories and methods of viewing/creating optical illusions. Marr (1980) was the first to properly relate the fields of psychology and neuroscience to computational methods. Specifically, Marr identified the importance of bottom-up (interacting small processing units) neuronal level computing as underlying visual perception. Computers in vision research are now a fundamental tool, and provide a link not just between the perceptual sciences, but also perceptual art and design. For an in depth discussion of perceptual theories see Gordon (1989), Goldstein (2001a) and Hoffman (1998).

3.1 Perceptual phenomena The way we see an object or surface, is defined by its visual properties. Most of the time we see the world as it is – a tree is a tree, a house a house and a dog a dog. This is a very necessary function of vision – if it wasn’t this way, our sight wouldn’t be particularly useful. However, the way in which the world is encoded, represented and interpreted by our brains enables massive amounts of visual data to be handled in a tiny biological space. Consider the amount of points of light that exist in any view of the world; then consider the amount of biological cells, neurons, that are available at any instant to process this information. Our brains achieve a resolution so fine as to be to pick out a needle in a haystack or recognise a friend amongst millions of other faces. Given the relatively tiny number of neurons involved in perceiving the world, their has to exist an enormous array of processing tricks and techniques to actually achieve the quality of vision we have. These tricks and techniques mostly happen as background, of unconscious, events. However, through illusion and optical effects we can expose and explore these tricks and processes to provide new explanations, or examples, of how our minds work. We will now show examples of visual illusions to demonstrate this concept. Examples have been organised under two broad headings: static and dynamic.

Static illusions As shown through the Gestalt notion of completeness, there seems to be a need for the mind to fill-in or compensate for missing parts of an image. The classic example of this is the Kansiza Triangle. In this case, no matter what knowledge we have of the image, we simply cannot override our perceptual mechanisms. This is effect is particularly strong in the White Illusion, where a dramatic difference in shade of grey is perceived even though they are in fact identical. In these examples, the illusion is static and remains static – as far as the visual system is concerned, there is no ambiguity in the image. A further example of this kind of perception is the Wundt-Fick illusion, where two lines of identical length are perceived as different (the vertical line seems longer than the horizontal).

Kanisza Triangle Grey Men Wundt-Fick (Hamilton and Rogers, 2004b) Figure 2: Static perception

Dynamic illusions Our perceptual systems can sometimes be shown to be dynamic. At a high level (visual processes involving complex regions of the visual cortex) of processing, this fits with Gregory’s (1997) constructivist theory – where the world model created by our brain is superimposed back into and onto the perception we have of the real world. In the case of ambiguous figures (such as Necker Cube and the classic Duck-Rabbit illusion), this results in a shifting image, oscillating between possible real-world representations. However, in the case of the Herman grid the dynamic appearance of dark spots in the white space of the grid can be accounted for by low-level cellular responses. In this case, since there are no clear perceptual options for the position of the illusory spots, their position constantly shifts.

Each of these illusions has been carefully constructed to demonstrate a single perceptual phenomenon. In reality, we rarely observe a single phenomenon, but rather these visual processes are working in parallel to provide a realistic mental model. These examples are provided to demonstrate that the mind has many perceptual techniques for processing the world and that most of the time these processes occur subconsciously. Illusions serve as entertainment, but also as a way of exploring visual perception in a non-invasive way.

Necker Cube Duck-Rabbit Hermann Grid (Hamilton and Rogers, 2004b) Figure 3: Dynamic perception

3.2 Perception of surface The use of visual perception in the arts is widespread. Since the renaissance, where perception of depth became commonplace, artists have used perception as a tool exploring how we perceived the world, and has been the interest of numerous visual scientists, for example (Goldstein 2001b and Zeki 1999). Since the renaissance, surface and depth have been particularly important – from providing real-world representation of perspective, to the 60s op-art movement optimised by Riley and Vasarely. Riley and Vasarely used the perceptual notion of illusory contours as a means to provide texture and depth to flat surfaces Figure 4 shows how simple repeated contours can give rise to the strong perception of depth on a flat surface. Depth and texture from op-art has from the start been of interest to visual perception scientists (e.g. Wade,1982 and Zanker, 2002).

Figure 4 : Repetition of contours shapes gives rise to depth In addition to depth and texture, the Gestalt figure-ground separation concept is important to the perception of surface. As with Riley type textures, a dynamic figure-ground separation can be obtained by slightly altering the pattern to define regions of depth, form and attention. The Ouchi Illusion (Ouchi, 1977), as explained by Mather (2000), has received considerable attention from the science community. While many theories exist, its true nature appears to be undecided at present. Whatever the perceptual mechanisms turn out to be, this is a particularly strong example of how surfaces can be altered by simple visual representations. Such images challenge the traditional view of ‘seeing is believing’. These examples provide stationary illusions of depth and texture, yet advancements in computer related technology has enabled complex moving images to be displayed as surfaces either on or off screen. This new area for research is explored in depth in later sections of this paper.

The Ouchi Illusion

Invented by the Japanese artist Hajime Ouchi (1977), a strikingly powerful illusion of depth and movement is perceived. The underlying perceptual mechanisms responsible is still a matter of debate.

Figure 5: The Ouchi Illusion

Controlling surfaces It is now becoming easier to control the visual appearance of a surface, whether through computer screen based technology (including projection) or non-traditional approaches, for example Rozin (online), where pixels are formed by the shifting surface of wooden elements to form a mirror image of the viewer. In a similar way Jones (online), embedded control enabled wooden pixels to appear across the surface of an antique Victorian writing desk. This approach of non-screen based pixel control is a welcome break from the saturation of tube, plasma and LED displays. New advances in microcontroller (tiny computers used for embedding technology into objects and spaces) technology and new materials are enabling new design areas encompassing science and technology. Of these areas, electroluminescent lighting materials, originally developed for backlighting displays, have been used to create new surfaces exploring abstract representations of surface. The History Tablecloth (Gaver et al, online) developed as part of the multidisciplinary Equator research project (Equator, online) uses electroluminescent materials to provide a visual history of objects as they are placed on, and removed from, a table surface. In this design, abstract images fade in and out to provide a mechanism for reflection or play, with the aim to challenge the traditional notion of domestic design as utilitarian. Abstract surface representation is a theme of the research presented in this paper and we will return to this area later in this paper. 4. Investigations Motion and depth perception are two areas that have historically received less attention than, for example, colour or form, since until relatively recently it has been nearly impossible to create and control moving images/parts. However, computers and film have radically changed this position; it is now possible to readily create artificially moving images using film and computers. Computers have especially changed research, as very fast, very high resolution images, can be generated and adapted very quickly - in short, images can be created that fool the mind in new and exciting ways. In fact, all of TV and computer-screen movement is an illusion. Points of light don’t actually move - adjacent pixels are lit up and plunged into darkness faster than the eye/brain can detect, leading to apparent motion where there is none.

Working with moving images to explore motion perception has one major draw back – short of turning this paper into a flick-book it is impossible to provide paper-versions of the work that is carried out. However, an on-line version of this paper has been created to support understanding of the concepts presented (www.interaction.rca.ac.uk/staff/rory/ead/ead.html).

The Art and Visual Perception research project makes use of recent advances in methods of creating moving images to explore, and at times question, the way in which we perceive the world. In this paper a series of methods, prototypes and artworks are described that can sit happily in both an arts and science context. In some examples science has guided the form and excitingly there is a strong possibility that new science has been created. We will now describe the research methods we use in our investigations.

4. 1 Prototyping the experience Prototyping is a key research method in this project. We use prototyping to represent observations, to implement sketches and to provide user feedback. Since most of our practice uses moving form, we would not be able to convey the experience of viewing and engaging without providing prototypes for people to view and engage with. Through the use of prototypes to provide experience, we are encompassing the approach of Gestalt methods of practice; however, empiricism is never far away and we have currently received funding from the UK Engineering and Physical Sciences Research Council to explore our methods/practice in a more empirical way. The approach of this paper is to provide an overview of practice and process. Over the next few sections we describe the methods we use to research natural and artificial perceptual phenomena, starting with Observational prototyping.

Observational prototyping We use film to document and observe natural dynamic qualities of surfaces, to provide inspiration, context and verification for many of the computational/electronic prototypes we use. Film is a way of recording the natural environment to provide access to natural examples of perceptual phenomena that occur either too remotely or too infrequently to be of use as a general discussion. By filming a natural surface, we can communicate the experience and perceptual effect observed by an individual to a much large audience – for example, it would be impossible to view the effect of waves of corn blowing in a Scottish field in June, to a research meeting in London in November. This process of observational prototyping is also used to verify computational sketches to provide inspiration and context for further work.

Computational prototyping Using mixed media, we create animated sketches as integral to our research method: from communicating a moving perceptual effect, testing the parameters, to implementing a user testing model. We find that using mixed media enables system independent models. Reas (2004), has documented the nature of uniqueness of a particular algorithm to a particular programming environment – and that the environment forces or always creates output of a recognisable style. For example, an algorithm run through Director and Lingo will have a very different look and feel to the same algorithm run through Visual Studio and OpenGL. Typically, a Lingo animation will contain sprites that are animated, where as openGl uses rendering techniques where individual pixels are manipulated. It is not the scope of this paper to compare and contrast Lingo and openGL, but it is important to point out that different programming environments/languages create a very different viewing experience.

Lingo OpenGL Figure 6: Comparison of look/feel of code environments

Electronic prototyping Embedded design, using microcontroller technology, is enabling new forms of surface to be designed. By, again, using different materials and prototyping techniques, new perceptual designs can be explored and compared to, or be based on, film and computer-screen based methods.

4.2 Depth on a flat screen Depth and motion are the main percepts that we explore as part of this research practice. We feel that this area is under represented in design and we will now show new ways to engage with the flat screen using depth and motion. Watching the world from a moving train, car or walking up a mountain can provide insight into the way we see things in depth. A photo from a car window can not contain the sensation of depth that you experience as you look from a car window. A rational measurement of depth, or knowledge about distance, can be gained from perspective or relative object size; but the sensation of depth is different. True 3D images literally leap from the page or screen. Perception has been used in this way exploiting the fact that the brain relies on binocular disparity (the difference in image between the two eyes) to see in depth. However this method of viewing either requires 3D glasses (red/green/horizontal/vertical polarization), or a special viewing technique (adjusting vision for the popular auto stereogram images). We have explored how we can exploit the visual mechanism of depth-from-motion to create new surfaces that provide depth without the need for augmentation or training. Based on the motion parallax effect and using observational prototyping (figure 7), we devised the Motion Depth Machine (Rogers and Hamilton 2003a) as a prototype drawing tool for drawing depth from motion.

Observational prototyping

Film from a moving car was made to document how objects moved relative to each other to provide a sense of depth. Hay bails were chosen for their pixel-like qualities.

Figure 7: Observing motion parallax

The Motion Depth Machine The Motion Depth Machine (Hamilton and Rogers 2003a) is a new tool for drawing depth-from-motion images. Depth can arise from the relative movement of objects or points of light. The motion depth machine is made from an array of dots. Groups of dots can be made to move in different directions at different speeds. The result is a 3D image, with the faster dots appearing at greater depths. Unlike autostereograms, no special viewing is needed – the image appears as soon as the dots move.

The Motion Depth Machine

The motion depth machine funded by the RCA’s Staff Research and Development Fund. It was shown at TheDigitalHub, Dublin, as part of their summer program 2003.

A grid of dots is displayed. Different regions of the dots can be given different motion vectors. In the example opposite, a static square of dots is surrounded by moving dots, with arrows illustrating the movement.

Illusory depth perception arises as a result of the relative movement of the dots in the array. The static region (shown in black) appears to pop-out from the moving background.

Figure 8: The Motion Depth Machine Ripple Effects – A surface design constant? Ripples are everywhere, from visual perception to social theories, and apply to all materials – whether animal, vegetable or mineral; from atoms to galaxies. High school physics provides us with two approaches to light and optics: waves and particles. Using the particle model, energy, or points of light, move from the source to the destination like a train moves from station A to station B. With waves, energy is transferred from one point to another as dominoes pass energy from start to finish. Most of the way we view screen-based surfaces is based on particles: we control each pixel an move each pixel from A to B, which is all very well and good and necessarily so. However, in nature we can observer surfaces behaving more as waves. Take the skin of an animal, the way it ripples as it breathes and twitches to unseen irritation; the way wheat fields come alive on a windy day; or waves on the sea lapping at the shore. We have archived and documented these surfaces to demonstrate that animal, vegetable and mineral surfaces all have this universal constant of design: ripple effects.

Animal Vegetable Mineral Figure 9: Ripples are universal

Phase Difference In Phase Difference, a two-dimensional array of rotating dots can be transformed into an illusory three-dimensional surface by changing the phase differences between adjacent rotating dots. This is a new way of adding organic liveliness and depth to a flat screen. Phase Difference was used to create ‘Like Silk’ (Hamilton and Rogers 2003b), winner of the audio-visual category for a wireless art. Phase Difference is potentially a new visual phenomenon and we are currently working with George Mather, professor of Experimental Psychology at the University of Sussex to explore how this effect works and its implications for empirical study.

Competition Prototype Figure 10: Like Silk

Scalable design Scalable design is a common research theme for the Human Computer Interaction (HCI) community. Scalable design refers to the design of graphical media that will operate over devices with different physical parameters – screen size, communication speed, resolution and colour palette size. This concept has wide reaching implications for not just graphics, but many areas of design as computer, mobile and screen-based devices become integrated and embedded into all areas of our lives. It is desirable that designs scale across the many existing and potential media such that we can provide generic design solutions, rather than expensive, time consuming specialist or designed-for applications.

In 2002, we used a public arts event to showcase and test our perceptual research prototypes on a grand scale. The event, Generic Sci-Fi Quarry (Hamilton and Rogers 2002), took place in a quarry located near Oxford in the UK, used large-scale projections and Dolby surround-sound to fill the quarry with moving image and high-bandwidth audio. Images of 20m x 15m were projected into the corner of the quarry to provide as sense of emersion and presence. A noticeable fact was that the images appeared not to suffer from distortion as the visual system was able to compensate for this single translation from flat to right-angled screen, and is a point for further investigation. The event achieved national and arts press coverage, and proved invaluable as mass-user feedback, dissemination and a unique prototyping environment. Perceptual effects included, biological motion (Mather, 1992), motion depth, illusory contours and apparent motion for example. More information can be seen on the project’s website (swansong, online). Figure 11: Generic Sci-Fi Quarry

Following from ‘Like Silk’, we were asked to produce a series of animations, based on our perceptual work, that would exist as mobile phone screen savers for a service provider in Korea. This manifested itself through the on-line exhibition mgallery (Hamilton and Rogers, 2004a). We were asked to make a collection of past and present sketches, prototypes and final works that could be downloaded. For this we used some of the short animations that were developed for Generic Sci-Fi Quarry, amongst others included Like Silk variations. Figure 12 shows examples of the work we presented.

The main research point to be gained from the events and exhibition detailed above is the natural scalability of images and effects that are based on perception. Often images, such as text for example, don’t translate across different medium – text on a mobile phone screen is very different to text on a webpage. However, if we use images that are fundamentally designed for, with and by, visual perception in mind then the end result are images that will not only provide viewers with a natural experience, but also work over many different scales.

Figure 12: mgallery work

Summary In this paper we have presented theories from visual perception that can be used as tool and object for designing new surfaces for old and new surfaces. From the pre-modern science methods and practices of the Gestalt movement, to the modern empirical approach, we provided an introduction to visual perception theory to provide background and context for the research presented in this paper. Art, Science, Technology and Design have been used in a naturally multidisciplinary research approach – we have not attempted to classify or place into category, the work that we do and continue to do. Rather we observe, prototype, present and reflect using science as a tool in the same way as we would use programming or video making as tool. At times science has been used as a source of inspiration with art as the tool for exploration, at others art has provided inspiration and science the process and method.

By observing how surfaces behave in the natural environment, we have presented a new design concept based on how waves travel across animal skins, the effect of wind on crops and the effect of tides and wind on water. By rotating simple points of light with different phase relationships, we can construct a wide variety of surface distortions that show dynamic Gestalt-like effects.

We have shown a collection of prototypes/tools/artworks that explore how theories and examples drawn from visual perception sciences can be used. One of the strikingly important observations of this research is the natural scalability of images/animations produced with this approach. Scalability is a concept that is rapidly becoming an essential component to design of cross- platform or cross-material systems. We have shown how the same visual process operates when images are blown up as projections of a quarry wall, as when images appear on a tiny mobile phone screen.

With recent funding from the UK’s EPSRC funding body, by working with the well known experimental scientist George Mather, we are intending to extend this research project from perceptual effects on-screen to perceptual effects with physical form. In this way, we will explore how new surfaces can be designed that have new physical presence and form that can occupy buildings, furniture, pathways and mobile computing.

Images that exist only in the mind provide a constant challenge for design and designers. Images that nearly everyone will view in the same way (for example the grey men illusion), based on light-levels that do not exist, brings into question the nature of what we see and what exists in the world. Using the Art and Visual Perception research project as a vehicle to explore optical effects and visual illusion, we aim to provide tools and demonstrations to enable richer designs of surface that naturally exist in an unnatural world.

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About the authors

Jon Rogers is a lecturer on the recently established Innovative Product Design program at the on the Interaction Design MA at the Royal College of Art. He has University of Dundee. He holds a Ph.D in Neural Computation and Visual Perception from Imperial College, London, and has worked as a postdoctoral researcher/tutor collaborated with Rory Hamilton (Royal College of Art) for many years on the ‘Art and Visual Perception’ research project.

Rory Hamilton is a practicing artist and tutor in Interaction Design at the Royal College of Art in London. Having origionally studied sculpture and then multimedia his work is now largely based around his research with Jon Rogers (Duncan of Jordanstone College, Dundee.

Author contact: (Jon Rogers) [email protected]

Dr Jon Rogers School of Design Duncan of Jordanstone College of Art University of Dundee Perth Road Dundee DD1 4HT

Rory Hamilton Interaction Royal College of Art Kensington Gore London SW7 2EU