More subtle than having a common look-and-feel or consistency is that of continuity.

The vision-processing centres of the brain have evolved to detect motion (visual perception) and as a consequence, continuity will be ignored while change will be readily noticed. This factors into PowerPoint slides as each have various features which will be consistent from slide to slide, for example, the title and the background.

While PowerPoint controls the background, the title can (usually accidentally) be modified even if the text stays the same. Either the text box containing the title may be moved, or an additional space may be introduced. Regardless of the cause, this will be noticed by a significant portion of the audience as the presenter moves from one slide to the next, and these will, once again, take the attention away from the presentation.

Another source of such minor variations are a sequence of graphics displaying a progression of actions. Factors coming into effect here include changes in size, colour, resolution, emphasis, location. Instead of focusing on the information the sequence of graphics is meant to convey, a portion of the time will be spent by the audience on detecting and being annoyed by these changes.

The most unfortunate consequence is that this will be seen as amateurish. More unfortunate is that in some cases, the brain will notice the change without registering what changed. In this case, the audience member will, unnecessarily, look at try to determine what caught his or her attention.

The best way to catch such errors is to quickly move through the presentation and focus on slide-to-slide commonality and ensuring that there is no such undesirable changes.