Three experiments were conducted to investigate the relationship between th
e credibility of information and later unconscious plagiarism of that infor
mation. In each experiment, ideas concerning ways to reduce traffic acciden
ts were presented from a more credible source (traffic planners) and a less
credible source (college freshmen). After a distracter task, participants
were asked to generate novel ways to reduce traffic accidents. In Experimen
ts 1 and 2, unconscious plagiarism of ideas presented from the more credibl
e source was greater than from the less credible source. In neither experim
ent was explicit memory for ideas from each source different in tests of so
urce monitoring or free recall. However, the difference in unconscious plag
iarism was eliminated in Experiment 3 by having participants generate the i
mplications of ideas at study. The results are discussed in terms of the ex
plicit factors that affect the incidence of unconscious plagiarism.