The degree to which the color is moved toward middleground depends on the amount of white added to it. Since the colors are pulled toward the middleground, each color reacts to tinting in its own way. Reds and oranges move further away, since they are forward of middleground. Yellow and yellow-green don't move much since they are already about at middleground. Greens and blues move closer with tinting, since they are normally in the background, behind middleground.
All colors end up at middleground as they are tinted completely to white.
An extremely effective use of tint is to add texture to a dark blue background by tinting areas, making them lighter blue, to show raised portions. A surprisingly small amount of added white will result in definite and pleasing depth change for blue. This can be easily accomplished in most graphics programs with the emboss function if you have control of the highlight and shadow colors. Don't forget to include some black in an embossed blue pattern to help define the location of the darkest blue. Shading a color tends to move that color further away, in proportion to the amount of shading, regardless of whether it is a foreground color or a background color.