I FINALLY found the original study that speaks to the effectiveness of using visuals.
From Robert E. Horn's book Visual Language, a study by John Sweller of high school students and industrial workers found that:
- Visual language produces better problem solving (45% answers correct on a test using conventional text and separate diagrams vs. 64% answers correct using integrated text and diagrams.)
- Visual language produces higher retention (22% more) and in less time (13% less.)
Additionally, the Wharton School of Business studied visual presentations in a business setting and found that they led to:
- 64% increase in immediate decision making
- a clear preference towards presenters who used visuals
- reduction in meeting time by 24%
- an increase in consensus in groups from 58% without visuals to 79% using visuals
- an increase from 50% of audience members persuaded using verbal presentations to 67% of audience members persuaded using verbal plus visuals
I HIGHLY recommend Horn's book as an encyclopedia of all things related to visual language.