Quote from Random.Capital:
Imagine the mythical "smart money somebody" learning something that is likely to make an individual stock make a significant move. This person is likely to have at least a little time to think through an action - the easiest action to take that doesn't disturb the market in the stock itself is going long an OTM position. This also has the advantage of (usually) being the most leveraged position as well (assuming they don't do something stupid).
Then you move to the next ring of players. They have second-hand information on this likely big move - but they also know it's second hand information so they are likely to take a position that's somewhat less likely to be "all or nothing".
Then the third ring out, with third-hand information...
Then active retail...
Then passive retail...
Then CNBC...
Then the pro mutual fund manager...
Ok you get the picture.
In each step outwards from the center of information, the confidence in the information gets weaker and weaker. The tendency then will be to take positions nearer and nearer ATM, as it will be perceived as being less risky. Until finally you're at the typical fund level where they're so ATM that they're buying the actual stock.
With each step outward, there should be a jump in IV, or change in Greeks consistent with increased sensitivity to directional movement - starting somewhere way OTM, and migrating inwards towards ATM, until finally the stock itself is moving.