The best answer is from an anonymous user who suffered from an arterial problem which reduced the blood supply to his heart and brain, making him forgetful, slow, and easily overwhelmed…
However, once I got used to it and resigned myself, it was great. Even though I knew I had a worrying illness, I was happy as a pig in mud. I no longer had the arrogance of being frustrated with slow people, I abandoned many projects which reduced a lot of stress, I could enjoy films without knowing what would happen (my nickname before this used to be ‘comic book guy’ if you get the reference), and I became amazingly laid back and happy go lucky. I got on with people much better. I developed much more respect for one of my friends in particular who I always considered slow – it turned out he is much deeper than I thought, I just never had the patience to notice before. You could say I had more time to look around. The world just made more sense. The only negative, apart from struggling to perform at work, and having to write everything down, was that I no longer found sci-fi interesting – it just didn’t seem important. (I’m not joking, although it sounds like a cliché.)
He did recover, and you will be pleased to learn that he regained his love of science fiction.
Another answer mentioned the Dunner-Kruger effect:
The Dunning Kruger effect is a cognitive bias in which unskilled people make poor decisions and reach erroneous conclusions, but their incompetence denies them the metacognitive ability to realize their mistakes. The unskilled therefore suffer from illusory superiority, rating their own ability as above average, much higher than it actually is, while the highly skilled underrate their abilities, suffering from illusory inferiority. This leads to the situation in which less competent people rate their own ability higher than more competent people. It also explains why actual competence may weaken self-confidence.
Kruger and Dunning proposed that, for a given skill, incompetent people will:
- tend to overestimate their own level of skill;
- fail to recognize genuine skill in others;
- fail to recognize the extremity of their inadequacy;
- recognize and acknowledge their own previous lack of skill, if they can be trained to substantially improve.
Studies on the Dunning Kruger effect tend to focus on American test subjects. Similar studies on European subjects show marked muting of the effect; studies on some East Asian subjects suggest that something like the opposite of the Dunning–Kruger effect operates on self-assessment and motivation to improve:
- Regardless of how pervasive the phenomenon is, it is clear from Dunning’s and others’ work that many Americans, at least sometimes and under some conditions, have a tendency to inflate their worth. It is interesting, therefore, to see the phenomenon’s mirror opposite in another culture. In research comparing North American and East Asian self-assessments, Heine of the University of British Columbia finds that East Asians tend to underestimate their abilities, with an aim toward improving the self and getting along with others.