Overcoming Bias looks at two research papers on overconfidence, concluding that we “are more overconfident on tasks we don’t actually expect to perform, and when we don’t expect to have to explain our evaluation to others”.
On performance:
Participants made predictions about performance on tasks that they did or did not expect to complete. In three experiments, participants in task-unexpected conditions were unrealistically optimistic: They overestimated how well they would perform, often by a large margin, and their predictions were not correlated with their performance. By contrast, participants assigned to task-expected conditions made predictions that were not only less optimistic but strikingly accurate.