"The time is past when a boy's chief possession was his bike and a girl's party wardrobe consisted of a fancy dress worn with a string of dime-store pearls Today's teenagers surround themselves with a fantastic array of garish and often expensive baubles and amusements. They own 10
million phonographs, over a million TV sets, 13 million cameras."--LIFE, August 31, 1959
This text underlies what growing phenomenon of the 1950s?