Recent quotes:

Adderall Concentration Benefits in Doubt: New Study

The last question they asked their subjects was: "How and how much did the pill influence your performance on today's tests?" Those subjects who had been given Adderall were significantly more likely to report that the pill had caused them to do a better job on the tasks they'd been given, even though their performance did not show an improvement over that of those who had taken the placebo.

Manipulating brain activity to boost confidence | EurekAlert! Science News

"Surprisingly, by continuously pairing the occurrence of the highly confident state with a reward - a small amount of money - in real-time, we were able to do just that: when participants had to rate their confidence in the perceptual task at the end of the training, their were consistently more confident". Dr. Hakwan Lau, Associate Professor in the UCLA Psychology Department, was the senior author on the study and an expert in confidence and metacognition: "Crucially, in this study confidence was measured quantitatively via rigorous psychophysics, making sure the effects were not just a change of mood or simple reporting strategy. Such changes in confidence took place even though the participants performed the relevant task at the same performance level".