Remarkably Confident People
No correlation between intelligence and shyness has ever been confirmed (and, in fact, in school settings shy children are often seen as unintelligent) but the generalisation that intelligent people are quiet persists.
Let's look at why this generalisation exists - I believe there are three seemingly contradictory roots:
1) Social awkwardness / inflexibility
The most pervasive misconception about intelligent people is probably that they do not want to communicate with "average" people. As someone who falls within the 0.01% percentile of IQ scores, I feel I can speak for the group we tend to think of as "intelligent people" when I say that I have never met someone that I could genuinely say was average or uninteresting. As I work and socialise with more people I only become more aware of how narrow a definition of intelligence we often have - and how harmful it can be to both "intelligent" and "average" people.
- One negative outcome of our narrow definition of intelligence is that many people who have been labelled intelligent since childhood struggle with social flexibility, because the idea that they are different to their peers has been reinforced so throughly in both school and personal settings. These people often fall into a pattern of being withdrawn, because they feel they do not know how to respond to social situations.
- People who score highly on tests (IQ and otherwise) early in life often struggle with low self-esteem later on. From my own experience, I can confirm that the pressure of being "the smart one" has lasting influence on how you feel about your achievements and abilities, because they can never measure up to what you feel is expected of you. Low self-esteem very easily triggers social anxiety, and therefore, a more quiet and withdrawn personality.
- True intelligence incorporates emotional intelligence and empathy, and genuinely intelligent people tend to be insightful about how other people are affected by their words and actions
- Sensitivity is often associated with a less assertive, more shy, self-critical, personality
- Therefore intelligence is often associated with the shyness that comes with increased sensitivity.
3) "Intelligent" people often prefer to incubate their ideas
As a final point I'd like to draw attention to the fact that certain people are external processors while others are internal processors. Most of the traditionally intelligent people I have met are internal processors, whether because of social factors or inherent nature.
- External processors problem-solve better when they are actually talking through their ideas. Logically, this often means that one hears their "draft" ideas rather than their polished ideas.
- Internal processors prefer to incubate ideas within their own minds and make sure they are somewhat confident in what they want to say before they say it. So their ideas come across as more polished.
TL;DR: "Intelligent" people are not necessarily shy, aloof, or taciturn. What they often are is self-critical and sensitive. People process and express ideas differently, which means they air their ideas at different stages of "readiness" and may seem more or less intelligent.