The Gestalt principle of “good continuation” says that graphic elements that suggest a continued visual line will tend to be grouped together. In addition, visual patterns with good continuation may suggest to the viewer that the pattern continues beyond the end of the pattern itself. That is, we mentally “fill in” or “paint in” the rest of the pattern.

Good continuation is important in the design of tables, especially in the alignment of columns. Readers should not look down a column to see the good continuation broken by a rule line that is intended to frame a subheading. Inexperienced document designers sometimes position subheadings in a centered position over the columns and then bound the subheads with horizontal rule lines above and below them. When designed in this way, the horizontal lines may interfere with the reader's ability to connect the column headings with the data. In effect, this strategy carves up the content into parts which are marked by the rule lines.

Unless the content of the columns changes from one section to the next, horizontal cues should not compete with vertical ones. To avoid this problem, subheadings should appear in the left-most column of the table as side headings. Document designers can conclude that unless they want to signal a rhetorically distinct text element, it is a good idea to maintain good continuation.