Alex Osborn, a partner at the New York advertising agency BBDO, began group thinking sessions there in 1939. In his 1948 bestseller Your Creative Power, he wrote: “The early participants dubbed our efforts ‘Brainstorm Sessions.'” He set out the rules: “Judicial judgment is ruled out. Criticism of ideas will be withheld until the next day.” And: “‘Wildness’ is welcomed. The crazier the idea, the better.”
In June 1958 Donald Taylor, Paul Berry and Clifford Block tested the method. They compared real brainstorming groups with the same number of people working alone, whose ideas were then pooled. The people working alone “significantly outperformed the real groups.”