Everything you do to motivate voters to cast their ballots is part of that big arena known as “advertising”. To be precise, you, as the organiser of an election, are also an advertiser during this time.
Advertising is an immensely diverse and heavily researched discipline. Through massive studies are conducted to work out which advertisement works best when, and why. Coupled with this is another major field of research: psychology.
If you are already an advertiser, you can use knowledge from the study of the effectiveness of advertising for your election – e.g. that memories or repetitions can contribute to motivation.