It’s an interesting OP, and one I could agree with on principle, except that this “American Middle” as described does not actually exist.
There’s a common misconception in this kind of analysis and thinking that statistical phenomenom actually represent people.
They don’t.
Most people think things like an approval rating represent how people feel about the President. What is actually being measured is what people are willing to say about how they feel about the present. It’s an important distinction, and it leads to several effects.
Most people have positive and negative feelings concerning something like the President. If something good happens, or he has success, people associate that with their good feelings and are statistically more apt to share their good feelings at that particular time. They hear good things happening, and they want to fit in, so they say good things. Similarly when something bad happens they associate that with their negative feelings. It fits in and it is appropriate to mouth those kind of sentiments, or so they feel. In reality, it is not their opinion that is so changing and malleable, it is what they are statistically likely to say about their opinion that changes.
This may sound shallow, but we all do it. Most people want to fit in. The classic example is the “no soap radio” joke. The joke is “two elephants are in a shower. What does one elephant say to the other?” The answer is “no soap radio.” If you tell the joke to somebody who hasn’t heard and laugh uproariously as you tell it (better still with a couple of other people laughing with you) the person hearing it is likely to smile or laugh or agree it’s funny. He’ll agree not because he thinks it’s funny but to fit in, or be polite, because he thinks it’s appropriate at that time.
It’s part of normal survival instinct. This is why most sane people won’t enter a Peta meeting with a live chicken and dismember it in front of the membership… or tell black people jokes among a group of black people, or engage in other behavior that is innapropriate to the particulars of time and place.
Good news for the President is an appropriate time and place to offer positive opinions, and people who feel sort of neutral will tend statistically to do so at such times… and say negative things on negative days.
Another factor that is present is that of the precipice. People’s opinions are subject to change. People who have a growing positive opinion about a President may be pushed over the precipice in their changing opinion by a positive event. Somebody who had a negative opinion about Bush who had that opinion slowly changing, so that he was reconsidering it may witness a few postive things like the Saddam capture and the Qaddaffi situation and that may be enough to cement his change.
In reality his position was evolving slowly and would have changed anyway. These events were just enough to push him over the precipice, confirm it and do it sooner than it would have happened before.
The same works the other way with negative events.
What you actually have when you talk about the “middle” is a large group with somewhat neutral feelings who voice positive or negative aspects of those feelings depending on what they percieve is appropriate and timely. Their opinions aren’t really changing, just what they are voicing. Within this group, there is a smaller subgroup who’s opinions are in the process of change but may change quicker subject to a precipice event.
It gets more complicated, but that’s the gist of it, and the effects are well-known to statisticians, surveyors, advertisers and such.
It also explains the seeming contradiction opined in the OP, that nobody on the boards that she knows is like that large malleable middle.
If they did exist, you would think they would be represented. This large malleable middle doesn’t actually represent people and their opinions. That’s not what’s really being measured. What’s really being measured is what people are willing to voice at a given time, and that is very subject to changing circumstances while the underlying opinions tend to be much less malleable.