DISCUSSION: ‘The value of Unstable Properties of Colour Sensations and their Dynamics’ Markus REISINGER, University of Technology Delft & Philips Research Europe m.reisinger(a)tudelft.nl The world as we perceive it is full of colours. Every object and surface that is visible has certain colour-properties letting them appear in their specific colours. Human ability to distinguish small differences in colours may astonish if we consider eleven basic colour terms1 sufficient to name any colour. The amount of colours that humans recognise and attach to their mental pictures of objects and surfaces is in comparision to the amount we can distinguish very limited. The actual visual appearance of our environment is influenced by colour substance and illumination. This combination creates the colour impression we observe as apparent. The apparant colour, together with the characteistics of the lighting, bears important information that refers to the genuine colour of an object or surface. All examples presented here demonstrate factors influencing the appearance of colours. As they can change over a period of time we categorize them as unstable properties of colours. Colour, when understood as a product of mental efforts, is a result of dynamic processes. If we look at the sensational input that our eyes receive when we perceive colours, then those signals cannot be considered as stable, as our sensations would suggest. In everday situations we hardly ever notice the variations in apparant colour that a coloured object undergoes through changes in light. Instead we do perceive objects having a genuine colour that is stable. Humans seem to prefer colours that appear stable; it is definitely convenient in situations where we have to make decisions on a colour choice. For example, to make a choice about a colour that communicates a specific message would be pretty much impossible if we were to consider that colours are able to shift. In many areas of design, as in other fields, we look accordingly at colour from a static point of view. We do so as we choose a colour for a room or as we choose a combination that fits a graphic or textile work. As colours are used to distinguish and identify objects it is logical that this decision is made upon an impression already existing in our mind. We can argue that as it does not take concious efforts to ignore deviations in colour appearance (e. g. as induced by lighting) that we need to consider them as natural and expected. Would that mean that all examples that demonstrate unstable properties are of artifical character? Indeed a vast majority of the situations in which we experience liability to change seem to be constructs, man made conditions that feature extreme characteristics. For example direct experience of colour contrast. Colour contrast is an instantaneous reaction that happens practically unnoticed as it induces an opponent colour of a surface on an adjacent surface. Under particular 1 Dependent on language two to twelve colour terms are considered as basic. All other colours are considered by most speakers of that language to be variants of these basic colour terms. English has eleven basic colour terms. CREATE: New Ways to use Print Technology conditions we do recognise the influence of colour contrast directly. This can be the case if conditions are set so that a large inducing surface that entirely surrounds the target surface is seen next to an unchanged reference. If we recognise the induction of another colour on the genuine we get an powerful and surprising impression. Also a change of appearance mode can make us see colours at first not recognised. This can be demonstrated by a very simple experiment that can be excecuted in any everday room. By looking through a paper tube we can simply direct our views to specific areas and we will discover colours not seen in the scene before. This mode is termed by Katz as film colour2 mode, but is also known as aperture mode. By using the paper tube we conceal objects and look at parts that appear with typical properties of film colours. One example of unstable appearance of colour in nature is goniochromism, which refers to hue changes that appear according to the angle of illumination or the angle from which the surfaces are viewed. This phenomenon can be observed in the appearance of wonderful colours in the wings of the Morphos (a tropical butterfly species). Those colours proceed from structure and only partly from pigments. In soap bubbles we can observe colours without any pigment contribution, but occur only as result of interference of light. There is in reality no concious choice for humans to prefer one appearance over another. The way things appear is a result of a variety of internal perceptual mechanisms. What humans do on the basis of immedate appearance, specifically the visual, is to attach values. Which brings us to the question; are unstable properties now rated positively or negatively? For those situations where we are aware of a shift in colour (for example as painted surfaces dry and appear not according to expectations anymore) we generally judge them as defectively influenced. Also the fading of colours of a printwork through ageing can similarly be considered as an effect of an unwanted colour instability. If we were to measure the absolute colour shift in the above examples, these might be minor compared to shifts caused by the presence of different light sources, but that shifts are recognised and get awareness causes differentiation in quality. Whereas in the case of lighting changes colour shifts will generally not be recognised. The reason that changes in colour are negatively evaluated is not necessarily based on the shift of colour, but might be influenced by associations as deviation from an ideal, and not a reversible change or mutation towards something else. There are also examples to name where dynamic properties of colour sensation are interpreted positively as informative, surprising, or fascinating. Physical colour or structural colour as in the butterfly example mentioned can surprise and fascinate. Changes in colour that appear according to defined conventions are considered as useful and can be applied to provide specific information, for example temperature. Through those occurances, which are truly fascinating, we can add art installations by artists like Flavin, Turell or Eliasson. They all apply in their works dynamics in colour sensations that reassure our awareness about some of the perceptual processes in action. Three examples are mentioned here. As in a Dan Flavin Installation like Untitled (to you, Heiner, with admiration and affection) where after a while the glowing green that was overwhelming fades to green-white, we might start to think about the first impressions. As in a James Turell installation like Wide Out, where an objectless coloured field evokes an experience that merges distance and illusion creating 2 Translation of german term Flächenfarbe CREATE: New Ways to use Print Technology atmospheric density, we might start to feel light/colour haptically. As in a Olafur Eliasson installation like Your welcome reflected, where transmission and reflection circle us in colours, we might start to question where colours are coming from. We can conclude that there are various properties of colour sensations that can cause unstable impressions. In general we only become aware of them in extreme conditions. Occurances of such seem more likely in man-made environments than in natural environments. As demonstrated, dynamics and instability of colour perception can elicit negative as well as positive valued reactions. Artists are at the forefront in exploring such colour phenomena, and manage with their explorations to astonish and fascinate. The following questions arose from the above thoughts, and are taken as initial input for discussion: What properties of colours might appear as unstable? What examples can illustrate such behavior? Do humans appreciate unstable and dynamic colour perceptions? Which unstable perceptions are interpreted positively and which negatively? Are unstable and dynamic perceptions dependent on situational condition and the context? CREATE: New Ways to use Print Technology Appendix Reviews of mentioned art works collected from internet resources: Dan Flavin: Untitled (to you, Heiner, with admiration and affection) exhibited in 2006 at the Hayward Gallery, London “The glowing green of Untitled (to you, Heiner, with admiration and affection) attacks the senses even before entering the particular space where it was housed during the exhibition. By affording those in the ticket-buying queue a view of the glowing (a common word in writing on Flavin) green through a frosted window, the curators allowed the audience a mysterious foretaste of what was to follow. On entering the gallery itself the omnipresence of the green (emanating from the fence of green tubes, perhaps 100 feet long, laid out at a slight angle across the floor) is overwhelming. Then strangely, the original colour fades, to be replaced by a faded green-white on the walls, and tubes that have turned almost white. On leaving, and then espying the artwork from another room, everything has returned to its vivid green. The seemingly changing colours are a trick of the human perception that continues to beguile. But it’s more than an optical trick that Flavin is playing; the colour floods and dominates the room in a godly fashion, demanding human participation.” Review from 5 February 2005 published at http://artreview.wordpress.com James Turrell: Wide Out exhibited in 1998 at the MAK, Vienna “By manipulating light and playing with human perception, Turrell's remarkable spaces isolate light, giving it form, depth, and mass. As much to do with vision and perception as painterly issues of light and color, shape, and form, Turrell's work suggest - a painterly sensibility - in three dimensions, while forcing a delightful investigation of the very act of seeing.” Henry Art Galleries on works by James Turell published in http://www.henryart.org/pastex/pastex2003.htm Olafur Eliasson: Your welcome reflected exhibited in 2005 at the ZKM, Karlsruhe “Your welcome reflected by Olafur Eliasson treats the phenomenon of coloured light in a special way. Eliasson makes use of a spotlight and several panes of glass to explicate Newton’s law as in a physics experiment: confronting the beholder with his own perception process.” Review from 19 November 2005 published at http://www.artdaily.com CREATE: New Ways to use Print Technology