In line with the spirit of the theme of the Conference the psycho-physiological effects of colour in terms of its three dimensions - Hue, Chromatic Strength and Lightness - will be discused by considering how the created metamorphoses affect our organism. It is well known how colour in the form of light and paint transforms a space. This occurring space metamorphosis can be conceptualized at a single moment in time - the synchronic level (syn = at the same, chronos = time) when comparing the same environment in different colours, but also at the diachronic level (dia = across, chronos = time) comparing our reactions, both affective and physiological, over a period of time whether minutes, hours or months. Studies carried out at Oxford over a period of ten years will be presented in which full scale spaces were evaluated by means of cognitive measures using Richard Kuller's theoretical framework. The results of two recent experiments carried out at the Environmental Psychology Unit of the Lund Institute of Technology, Sweden, will also be discussed by reference to both synchronic and diachronic levels of conceptualization. The results of these experiments are based not only on the subjective measures used so far but also on physiological measures such as EEG (alpha, beta, delta and theta) activity at the cortical level and EKG and arrythmia at the autonomic nervous systems. The first area of experimental interest is whether long wave length colours are more alerting and activating than short wave length colours. Is there a difference in our responses between colour light and colour pigment? Secondly, are there any differences regarding the Hue-Heat hypothesis by using subjective measures of perceptual heat estimation compared to behavioral measures over a period of time? Thirdly, how far does colour affect our subjective estimation of time? Do certain colours accelerate the subjective passage of time compared to the chronological experience?