Dementia can cause changes in thinking, judgement, and personality. Brain damage can, too.
I think what effects a normal person's thought processes and how they express their emotions is personality type, rather than intelligence.
That's a fair point, and I think there is a lot within this sentence of yours. How might we consider what a "normal" person is? Do any of us even know what a normal person is? Should we even try to define it?
I think someone's personality type undoubtedly plays a role in how they are likely to process thoughts and even emotions. Then I wonder how 'intelligence', particularly emotional intelligence might develop someone's personality.
Someone who is naturally empathetic, as a personality trait, might understand the emotions of others, but their ability to reflect on that person's own feelings and respond thoughtfully might be challenging. It might depend on their level of emotional intelligence?
It seems to me that someone's intelligence as a whole is pretty much immeasurable, in a way that can be compared to someone else. There is too much of a jigsaw to put together to figure that one out. So many variables to consider, such as influences from, upbringing; past positive and negative experiences, and how that might have shaped emotional intelligence. The people someone mixes with, and how much they are influenced by them, or how they might use their own emotional intelligence as a way of filtering the influences from others.
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My 13 year old niece will soon have an assessment to see where she is on the autism scale. She doesn't interact well with people -- shies away from them. Very little eye contact with people. To me, not that I'm an expert, she seems in many ways to be quite intelligent. She's very constructive, in that she likes building & creating things. Goes deep into subjects, immersing herself with as much information as she can find, to the point where she becomes unaware of her surroundings and doesn't hear people talking to her. She prefers to figure things out for herself and can keep herself occupied for hours.
A few weeks ago I asked her what she would like from me for Christmas. As well as a Nintendo Game Controler, Nintendo games, and even more Lego, she asked me to get her two books: Stalingrad, and Russia Revolution And Civil War -- both books by Antony Beevor. She has been interested in this type of thing since she was eleven. She has several books on WW2. Recently she went to the Imperial War Museum in Manchester with her dad. Whilst she was there she brought two small model planes that she has now put together herself. A WW2 Supermarine Spitfire Mk2 and a Messerschmitt 109.
She showed me these two model planes she had made when I visited my brother over Christmas. She left them with me in the kitchen, then she quickly ran upstairs. I kind of got the impression she wanted to interact with me and talk about the planes, but couldn't quite bring herself to do it. Eventually, she came back downstairs, and we talked a little. A few days later I gave her my copy of the movie, The Battle of Britain.
This young girl fascinates me. In some ways I see some aspects of my younger self in her when I was her age. My niece seems "normal" enough to me. As alluded to, intelligence, personality, and emotional depth are vast subjects, and no doubt are interconnected -- influencing each other. I would say that intelligence is hard to measure -- and to measure by which or whose scales? Someone's I.Q. is only a small aspect of someone's intelligence, in my opinion.