Can social circumstance whither one's intelligence?

It can't lower your actual intelligence, but it can definitely affect your performance on an IQ test. The opposite is also true. The less credence one gives to others' opinions, the "easier" one functions.

You could say that such things actually raise and lower intelligence, "in the moment", as it affects thought. It "clutters" and "tangles" (or un-clutters and untangles) the mind.

The younger a person is, the easier it is to see the effects and the easier it is for a young person to un-clutter his or her mind, once the phenomena is explained. Children often do things they shouldn't, technically, be able to do. This is because they haven't, yet, been told or convinced that they cannot do such things or that they "don't understand". i.e. their minds are far less cluttered than a "socialized" adult and, in many instance, children are far more intelligent than adults.

Some call it "wisdom".

Others opinions have everything to do with them and nothing to do with you, except in the "weight" you give them. And I'm speaking literally, not metaphorically.

'Trusting" others is not good for you, OR for them. Others can only see and speak from their own perspective and while that perspective may be valid, and in accordance with their beliefs, it has nothing to do with you. "Trust" is a terrible burden to put upon another person as they are not equipped to satisfy it. You don't have to "assume" they're "lying", you only have to understand that they speak from their own perspective and that your perspective - and therefore, your life experience - is entirely different. i.e. you can and do "know" things that no one else can ever "know". You're quite awesome! All of MAN is quite awesome!

Definitely. The mind is a powerful thing. If you believe that your stupid, you start to enact it. When you believe something it often effects your brain and body. It's called the placebo effect. You see this a lot in experiments where doctors give patients a sugar pill, and the patients thought that they were receiving Advil. Yet, they were relieved of pain. The power of the mind, my friend.

Absolutely. This is repetitive negative hypnosis, planting a seed in the mind which then complies and creates what is said and heard over and over and over again.

But, it is reversible since it is not structurally natural.

what about the opposite. if someone was meed to feel intelligent, could they become smarter and make connections that wouldn't be possible otherwise?