Depth Cues

I do highly recommend going over the PowerPoint for this one as the images are helpful.

Size Difference: Changes in the relative size of objects based upon distance.

Convergence: Narrowing of objects as they project into the distance.

Textural Diffusion: Little lost on this one. I believe that the shading of diverse textures gives away its three dimensionality.

Pretty sure this is just the effect that all textures become more blurred and neutral-looking (less sharp and colorful) as they get further away. Think of the roof of a house; up close you see the shingles and texture of it, but at a distance it turns to 1 flat color. Think mipmapping or anisotropic filtering in graphics (or is it trilinear? I get those mixed up). The point is that if you see a small-looking house with great detail you'll think it's a small scale up close (like a miniature model or something), but if you see a small-looking house with flat details you'll think it's far away. --Brandt
From another film professor's PowerPoint found on Google: "Our ability to create the illusion of depth on a flat surface by creating differences of detail in texture and color."

Movement:

Object movement perpendicular to picture plane works as a depth cue
Three-dimensional camera moves (dolly in/dolly out, tracking, and boom/crane) work as depth cues

Aerial Diffusion: The blurring of objects in the far distance by the air and atmosphere

Tonal Separation: Brighter objects on top of dark objects appear closer.

Color Separation:

Overlapping: Duh.

Another worthwhile topic that Andrew covers in this vein is Focus and Depth of field.