Two experiments demonstrated that a subjective feeling of familiarity deter
mined whether participants processed persuasive information analytically (s
ystematically) or non-analytically (heuristically). In the first experiment
, individuals unfamiliar with message content showed differential attitude
change when strong versus weak arguments were presented, whereas individual
s made familiar with the message through unrelated repetition failed to do
so. These results were confirmed in a second study that manipulated familia
rity through subtle repetition and eliminated procedural priming explanatio
ns of the effect, implications of these findings for familiarity as a regul
ator of persuasive processing are discussed.