Plagiarism as an illusional sense of authorship: the effect of predictability on source attribution of thought.

Previous studies have shown that contextually high-predictability ideas are essential for one to sense the authorship of thoughts and that having the sense that one came up with an idea of one's own, instead of through hearing of another's idea, results in the feeling that one has output the ideas. In this study, we investigated the effects of an idea's predictability on the misattribution of another's thought to oneself. The participants were asked to write down two original ideas about how to use various objects while avoiding the duplication of another's ideas that had been presented beforehand in an input-output phase. In the monitoring phase (1 week and 1 month after the input-output phase), the participants were asked whether each idea had been generated by them, by another, or not generated at all. We found that a high-predictability idea is likely to be regarded with the notion "I generated the idea." This tendency increased with time, suggesting that participants were more likely to have a sense of authorship when high-predictability ideas were presented. We also discovered that they were more likely to conclude that the source of high-predictability ideas was the "Self." We discussed the results from the viewpoint of the participant's sense of agency as well.