The surprise that improved attention two pages later
Here are two heat maps from a research project I completed, where I was analyzing what happens in the buyer's brain when they process highly complex and technical information from a thought-leadership eBook. The heat maps show buyers' aggregate attention on page 13 out of 20 pages. The first screenshot is from the group that saw the original version of the eBook, which contained a series of technical pages and stock photos, and the second screenshot (scroll to the right to see it) is from the group that saw the file where we replaced the stock photos with more creative, less predictable ones. Two pages before viewing these paragraphs, you see here... people viewed either a predictable or a more original image than they expected.
Note how in the more original condition (second screenshot), people pay more attention to the text, even two pages after they had been primed with something less expected: The paragraphs receive deeper fixation, and the numbers are read more carefully. This is pure luxury because numbers are typically scanned in these dense materials.
Practical guideline: consider intensifying a stimulus after your viewers habituate and enjoy the extra attention that lingers. The less predictable images increase temporary attention and also cognitive readiness for what happens later on. In other words, the original pictures told the brain: pay attention, something interesting may be happening later. So, it's worth the effort to be creative, even in technical communication, because it appears that the unpredictable has increased tolerance for complexity.
(PS: Note how no one is paying attention to the decorative image at the bottom, but they do pay attention to how many pages they have to go through at the top.)