Final answer:
The fears regarding the strong effects of media messages originated from propaganda campaigns during World War I, when mass media was used to disseminate pro-war propaganda to influence public opinion and encourage support for the war effort.
Step-by-step explanation:
The fears that media messages would have strong, direct effects on individuals grew out of the extensive propaganda campaigns that started during World War I. With the innovation of mass media, countries could disseminate powerful propaganda to shape public opinion and bolster support for the war effort. The U.S. government, recognizing the persuasive power of popular media such as newspapers, radio broadcasts, and films, launched ambitious propaganda initiatives to rally the American public and sustain the war effort.
For instance, the U.S. created the Committee on Public Information during World War I to release pro-war propaganda. Various media forms were utilized to portray the enemy in a negative light and to encourage public support for the war. The popularity of radio and the prevalence of newspapers amplified these messages, influencing public opinion to unprecedented levels. Such wide-reaching propaganda efforts during World War I established a lasting concern over the influential capacity of mass media.