Building upon early research from rural sociology, diffusion of innovations, public opinion poll data, and information campaigns, Tichenor et al. (1970, 159–160) posed the hypothesis: “As the infusion of mass media information into a social system increases, segments of the population with higher socioeconomic status (SES) tend to acquire this information at a faster rate than the lower status segments, so that the gap in knowledge between these segments tends to increase rather than decrease.” The less advantaged were predicted to gain knowledge but at a slower rate than more advantaged groups. The gap can be studied at one time point or over time. Tichenor et al., also known as the Minnesota Team, focused on public affairs and scientific knowledge (→ Political Knowledge). They assumed that knowledge growth was irreversible (although forgetting can occur) and that ceiling effects occurred at varying rates for different SES groups or else had not been reached (→ Media Campaigns and Perceptions of Reality; Media Use by Social Variable).