The reported studies are part of an ongoing interdisciplinary collaboration linking research on fractal geometry and the description of natural forms with research on the connection between aesthetic appraisal and human functioning. The perceived naturalness has been found to be one of the most significant predictors of environmental preference and in more recent years, a large body of research, using both self ratings of affective states and physiological measurements, has suggested that natural environments have particular restorative qualities with a particular positive effect on stress levels and the capacity to regain the ability to focus attention. Nature is suggested to be restorative because it is fascinating and effortless to attend to. But why is attending to nature’s patterns less demanding than attending to other patterns, and why does nature hold our attention? In nature many patterns have self similarity between scales, or in other words, nature has a fractal geometry. Our hypothesis is that the way complexity is organized in fractals could explain why such patterns are preferred and both fascinating and effortless to attend to. We have been investigating this issue in a number of studies using landscape silhouettes. Our initial studies, using silhouette outlines extracted from real landscape photos, showed that the perceived preference and naturalness peaked around a fractal dimension of 1.3. In the here reported studies artificial landscape silhouettes were created by using fractal lines generated with a computer. For these artificial silhouettes the result shows no peak but instead a continuous decrease in perceived preference/pleasantness and naturalness with increasing fractal dimension. The difference in results between the two types of silhouettes indicates that there is a different frame of reference for semantic evaluations of extracted and artificial silhouettes. It also points to roughness of the pattern as a potentially important additional factor. The implications of being able to tie perceived preference, naturalness and restorative ness to a measurable and designable factor like the fractal dimension is considerable. It provides not only a deeper understanding of why nature's patterns facilitates restoration but it opens the possibilities of applying this quality in a conscious way to built and indoor environments as well. A second part of the present study, from which data is currently being analyzed, involves EEG responses to the same artificial fractal silhouettes. The research is supported by the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning.