The eye – and thus the mind – is drawn towards motion.
This probably harks back to the earliest days of human evolution; movement might mean predators, and predators might mean you’ll become someones dinner as opposed to getting dinner yourself. Advertisers have tapped into this fact for ages, and one can often find advertisements on clocks, or clockwork used to drive animated displays.
And as I was browsing the web, i found pictures of one of the later:
Listed on the site i found it as “animated advertising display, articulated pressboard figure of a father shaving with a baby on his knee, spring driven pendulum movement with simple escapement on a wood base. 1912”
As far as I can tell the clockwork makes the rocking chair, uhm, rock back and forth, while a pair of lever uses that motion to make the shavers hand move across this face. Fairly simple, and in an age before full motion video presumably effective in grabbing shoppers attention.