The middle of the 20th century saw a number of very important changes in American popular music. The field of pop music developed tremendously during this period, as the increasingly low price of recorded music stimulated demand and greater profits for the record industry. As a result, music marketing became more and more prominent, resulting in a number of mainstream pop stars whose popularity was previously unheard of. Many of the first such stars were Italian-American crooners like Dean Martin, Rudy Vallee, Tony Bennett, Perry Como, Frankie Laine and, most famously, the "first pop vocalist to engender hysteria among his fans" Frank Sinatra. The era of the modern teen pop star, however, began in the 1960s. Bubblegum pop groups like The Monkees were chosen entirely for their appearance and ability to sell records, with no regard to musical ability. The same period, however, also saw the rise of new forms of pop music that achieved a more permanent presence in the field of American popular music, including rock, soul and pop-folk. By the end of the 1960s, two developments had completely changed popular music: the birth of a counterculture, which explicitly opposed mainstream music, often in tandem with political and social activism, and the shift from professional composers to performers who were both singers and songwriters.