The first phase of postmodernity overlaps the end of modernity and is part of the modern period "(see lumpers/splitters, periodization)". Television became the primary news source, manufacturing decreased in importance in the economies of Western Europe and the United States but trade volumes increased within the developed core. In 1967–1969 a crucial cultural explosion took place within the developed world as the baby boom generation, which had grown up with postmodernity as its fundamental experience of society, demanded entrance into the political, cultural and educational power structure. A series of demonstrations and acts of rebellion – ranging from nonviolent and cultural, through violent acts of terrorism – represented the opposition of the young to the policies and perspectives of the previous age. Opposition to the Algerian War and the Vietnam War, to laws allowing or encouraging racial segregation and to laws which overtly discriminated against women and restricted access to divorce, increased use of marijuana and psychedelics, the emergence of pop cultural styles of music and drama, including rock music and the ubiquity of stereo, television and radio helped make these changes visible in the broader cultural context. This period is associated with the work of Marshall McLuhan, a philosopher who focused on the results of living in a media culture and argued that participation in a mass media culture both overshadows actual content disseminated and is liberating because it loosens the authority of local social normative standards.