The extent to which the Efficient Market Hypothesis is true, and the extent to which EMH is believed to be true, are co-determined in simultaneous equilibrium by "supply" and "demand". Here's the picture:
The downward-sloping (hence "demand") curve shows the extent to which EMH is true as a function of the extent to which people believe EMH is true. At one extreme, if nobody believes that EMH is true, so people believe there is no relation between market prices and fundamental values, then each individual has a strong incentive to research carefully the fundamental values of assets before buying and selling, and so market prices will reflect all the information available to everyone, so EMH will be true. At the other extreme, if everyone believes EMH is true, so that market prices already reflect all available information on fundamental values, then no individual has any incentive to collect and process that information, and everybody picks assets by throwing darts, or buys the index, so market prices will not reflect any available information on fundamentals, so EMH will be false.
The upward-sloping (hence "supply") curve shows the extent to which people will believe that EMH is true as a function of the extent to which it is actually true. If EMH is totally false, people will (eventually) learn that it is false, and that it is sensible to collect and process information on fundamental values. If EMH is true, people will learn that too, and won't bother to collect and process information.
There will probably be lags in both curves. There will be a lag in the supply response if learning the extent of market efficiency takes time and experience. There will be a lag in the demand response if it takes time for market prices to drift away from fundamental values when people stop collecting information and start throwing darts instead. Maybe you can get a cobweb model out of these lags. Maybe that cobweb model would look like Minsky-esque cycles: markets start out efficient, so people slowly learn they are efficient, so they slowly drift away from efficiency...etc.
Don't take the picture too seriously. It's only a heuristic device. I don't know precisely what should be on the axes. The "extent to which EMH is true" could be perhaps be defined as the R2 of market prices on fundamental values. But then different people have different bits of local information, and different costs of collecting and processing information, so it's not too clear exactly how much information should be reflected in fundamental values for 100% EMH. The "extent to which people believe EMH is true" could be defined as x% of the population believes that EMH is 100% true, or 100% of the population believes that EMH is x% true, or some combination. And what's important is whether they act as if they believe it is true, of course.
Since I don't know precisely what's on the axes, I can't say whether the demand and supply curves should be curved or straight, or whether they should hit the corners.
If a change in the market structure (allowing short sales?) made the market a more efficient processor of information, that would be represented by an upward/rightward shift of the demand curve. Note that a shift in the demand curve would be partly offset by a movement along the curve. A decrease in the costs of collecting information would be represented by a leftward/upward shift in the supply curve (more people collect information, thereby acting as if they believed EMH were false. Again, the shift in the curve is partly offset by a movement along the curve.
I haven't seen this picture drawn before, but I don't know if it's original. All the bits of the picture are certainly widely known. It helps me think about EMH.
I have made a distinction between fundamental analysis of asset values vs. buying the index/throwing darts. I'm not clear yet on where technical analysis fits in.