Pop music sampling (from the 1980s) have also been utilized as methods for the creation and elaboration of pop music. By the early 1980s, the promotion of pop music had been greatly affected by the rise of music television channels like MTV, which "favoured those artists such as Michael Jackson and Madonna who had a strong visual appeal". The latter half of the 20th-century included a large-scale trend in American culture in which the boundaries between art and pop music were increasingly blurred. Between 1950 and 1970, there was a debate of pop versus art. Since then, certain music publications have embraced
Pop music in pitch progressions, growing average loudness levels, less diverse instrumentation and recording techniques, and less timbral variety, which declined after reaching a peak in the 1960s. "Scientific American"s John Matson reported that this "seems to support the popular anecdotal observation that pop music of yore was "better", or at least more varied, than today’s top-40 stuff." In May 2018, researchers at the University of California, Irvine, concluded that pop music has become 'sadder' over the last 30 years. The elements of happiness and brightness have eventually been replaced with the electronic beats making the pop music more 'sad yet danceable'.