Sixty Years Later A Replication Study of McGuire's First Inoculation Experiment

Inoculation theory was introduced 60 years ago, after McGuire and Papageorgis (1961) published their first study on how resistance to persuasion can be induced. They demonstrated that people who are pre-exposed to weakened arguments against an attitude or position they currently hold (i.e., inoculated) are less affected by a subsequent strong counter-attitudinal message than people who are pre-exposed to arguments consistent with their attitude (i.e., supportive defense treatment) or to no arguments. Although these results significantly impacted both science and practice on a general level, rigid tests of the key theoretical propositions are lacking. We conducted a highly powered replication study (N = 679) and found that an inoculation treatment is more effective in increasing resistance toward persuasion compared to a supportive defense treatment and a no-treatment control condition. Our results were mostly consistent with McGuire and Papageorgis's original work.