What is the Illusion of Completeness?
The illusion of completeness is a usability issue, leading users to miss out on relevant content on a web page. This occurs when users do not realize that there is more content to be explored on a page because the design suggests that they reached the end of the page, and there is no need for more scrolling.
While this is a handy heuristic, only research done on actual users can validate your design.
How does it happen?
- Large hero graphics/image  take up all the space above the fold and there is no or only weak visual cue for the user to scroll
Large image above to fold, with a “LEARN MORE” call to action button - 2. A clear horizontal line, or other segmenting element (such as expansive white spaces, advertisement, social sharing icons) lead the user to assume that they reached the end of the content offered on the page.
How to Avoid it?
The goal is to avoid sending the message that the reader has reached the end of the page.
- You may want to choose a smaller sized hero image or carousel so that they do not take up the whole “above the fold” area.
- Make sure that the white space between sections is not too wide
- The horizontally neighboring segments should not all start and end at the same spot. Here is an example from the Startribune (retrieved on 1/4/2017) . The small news segments in Column A always end at a different point from where Column B’s segments start or end.
