Which appearance attributes (size, opacity, color saturation, color hue, weight, blur) should encode hierarchy levels, in what rank order of perceptual salience, and what magnitude of steps between levels? (a sub-question that arises while solving: What is the best way to display concept mapping and diagram trees in this app (a software application) for the concepts being shown?)

I need a few details before I can give you a solid answer.

**1. Context & Use Case** What is the specific domain? Is this for education, technical docs, or UX flows? Who is looking at it? Novices or experts? What are they doing? Learning, editing, or just navigating? How deep does the tree go? Two levels or ten?

**2. Perceptual Goals** What does the hierarchy need to say? Parent-child links? Priority? Both? How many distinct levels must look different? Three? Five? More?

**3. Display Constraints** What screen size and resolution are we dealing with? How many elements can be visible at once? Do you need colorblind support or grayscale printing? Dark mode, light mode, or both?

**4. Interaction Patterns** Is it static? Or do users expand and collapse nodes? Do you need print output?

Once you clarify these points, I can tackle the rank-ordering question using established principles:

* **Position/depth**: Leftmost equals hierarchy encoding. Highest salience. * **Size**: High salience. Easy to scale. * **Color saturation/hue**: Medium salience. Watch out for accessibility. * **Weight**: Medium. Subtle. * **Opacity**: Lower. Can hurt legibility. * **Blur**: