When people perceive a visual field, the patterns that emerge depend on the unique characteristics of the elements of the field and the relationships among the elements within the field.

A device that can help promote grouping of related text elements is shading. It is important that the shading is applied lightly, staying within the range of a 10 to 25 percent gray screen.

However, if cues, such as shading, are used inappropriately, they can be quite misleading and may encourage readers to assign meaning to what has become a the visual distinction.

Any sharp contrast will draw the reader’s attention. Moreover, the greater the contrast, the more salient the effect.

Document designers need to consider how the design of contrasting visual cues encourages readers to group the content. They need to evaluate whether the grouping helps readers to make reasonable (and appropriate) inferences about the internal relationships among the parts of the document. They need to answer: Do the visual cues support the rhetorical goals for understanding and making use of the content? If document designers succeed in doing this, readers won't have to deal with documents that have the “gratuitous grays”—screens of gray that decorate while they obfuscate.