The ideas that emerged when R&B’s heaviest heads let it all hang out make for a compelling chapter in the story of American music.By the time the psychedelic revolution dosed America’s collective consciousness in the late 60s, Motown Records had spent the decade’s first half at the front of just about every new move in R&B and soul. And the label wasn’t about to lag behind when it came to keeping pace with the wildly blooming counterculture. R&B artists were used to being a step ahead of rock ‘n’ roll, with the world’s most influential rockers scrambling to adopt the...