Final answer:
In the 1920s and 1930s, research objectives shifted towards examining consumer behavior.
Step-by-step explanation:
In the 1920s and 1930s, there was a shift in research objectives towards examining consumer behavior. This can be seen in the passage where it mentions the dramatic economic growth of the decade, with factories producing consumer goods that were marketed and distributed throughout the nation. The rise of a national consumer market and the emphasis on material wealth and consumption reflected a shift in research towards understanding consumer behavior.