A study investigated the idea that the amount of knowledge viewers extract from exposure to television is a function of the amount of mental effort involved in processing the program content, and that the mental effort invested in viewing is partly a function of people's expectations about the demand characteristics associated with the content. Since research data have established that people report using greater mental effort for viewing Public Broadcasting Service (PBS) programing than for commercial network shows, subjects in two experimental conditions were told that they were going to view a show intended for broadcast on PBS, while those in the other two conditions were told that the same show was to be shown on commercial television. In addition, one group in each condition was told that it would be asked to evaluate the show after viewing, while the other two groups were told that they would have to complete a questionnaire afterwards. Immediately after viewing, all students completed an instrument measuring their affective responses to and learning from the show. Results showed a trend of increased learning from the groups told that the program was designed for PBS, although this was over-ridden in the group warned that it would be questioned afterwards. The mental effort reports were inconsistent with previous research showing greater effort being used for PBS program content. (FL)