Here are some links to web resources dealing with Visual Hierarchy. This material is mainly related to graphic design, and more specifically to web site design, however it would be really interesting to extend the concept to artifacts in general.

• Luke Wroblesky. Visible Narratives: Understanding Visual Organization; also Visual Communication & Web Application Design (pdf)
  
• Pete Faraday. Visually Critiquing Web Pages;
• Monash University Web Style Guide. Create a visual hierarchy;
• Web Style Guide. Visual Hierarcy;
• Web Design from Scratch. Visual Hierarchy for Web Page Design;
• Great Web Design Tips. Create a Clear Visual Hierarchy;
• Visual Hierarchy Defined;
• Web Design Guide. Visual Hierarches.

Many of these documents are informal guidelines for graphic designers. I believe they may be a good starting point (or at least give some hints) for the definition of a 'fruition model' for aesthtic artifacts.