three social scientists explored the differences between what they call "declarative" self-talk (I will fix it!) and "interrogative" self-talk (Can I fix it?). They began by presenting a group of participants with some anagrams to solve (for example, rearranging the letters in "sauce" to spell "cause".) But before the participants tackled the problem, the researchers asked one half of them to take a minute to ask themselves whether they would complete the task – and the other half to tell themselves that they would complete the task.
The self-questioning group solved significantly more anagrams than the self-affirming group.
Doubt is the reason that lead did not become gold overnight in the Middle Ages and it still works its ugly magic today.