The mood of an image
Paintings and other piece of art affect your mood. Happy, depressing, scary, cute, funny. Often you cannot pinpoint why, but it happens.
The same is true with photographs. When selecting images for your presentation, go beyond the functional specs of the photo: it needs to contain a self driving car, a person on a mobile phone, a clock.
How does the picture make you feel? Colors, perspective, proportions. Pictures can be beautiful and depressing at the same time. When given a choice, maybe the slightly less pretty but more uplifting image is the one to go for.