Well before my time, there were print and press Art Directors. Some of the more conscientious of their number became interested in a thing they called "effectiveness". Why would one ad work better than another ? David Ogilvy wrote some rules for his agency. 

A guy named Colin Wheildon* researched the subject for 7 years! And although that research is now over 20 years old there I've found no subsequent studies that have disputed his findings.