Rock And Rolls is your anwser
Answer:
The 1970s saw some of the highest rates of inflation in the United States in recent history, with interest rates rising in turn to nearly 20%. Central bank policy, the abandonment of the gold window, Keynesian economic policy, and market psychology all contributed to this decade of high inflation.
http://www.polytechpanthers.com/ourpages/auto/2012/1/24/45532409/ItalyandGermanyafterWWI.pdf
The answer is Perspectives, they taught themselves about different perspectives to help them put depth into their artwork.
