PowerPoint design: Background images that cause sensory failures

A student who recently gave a PowerPoint presentation in my class was aiming for an industrial-type appearance in his slides. The background was sliver with black holes. The image looked like a kitchen colander, but flat. The font was small and black.

The overall appearance was similar to this:

This slide design fails on a sensory level. The background image has grey and black that is similar to the font, leading to a low degree of contrast between the text and the background. The image is very detailed, which produces a noisy feeling. Finally, the text is simply too small to be seen from a distance.

An important design principle for sensory success is to have a high degree of contrast between the foreground (text) and the background. Our visual system works by detecting the degree of difference. Thus, designs that decrease contrast can be difficult to read or understand.

Credit: The background image was based upon a free image from the following source.
https://www.peakpx.com/637287/rubber-grid-regularly-floor-mat-backgrounds-silver-colored