Much early commercial radio was completely freeform; this changed drastically with the payola scandals of the 1950s. As a result, DJs seldom have complete programming freedom. Occasionally a special situation or highly respected, long established personality is given such freedom. Most programming is done by the program director. Program directors may work for the station or at a central location run by a corporate network. The DJ's function is generally reduced to introducing and playing songs. Many stations target younger listeners, because advertisers believe that advertising can change a younger person's product choice. Older people are thought to be less easy to change.