Green,
Here's how I used to shoot: Pick a spot and then the proverbial "bore a hole" in the spot; then I'd attempt to calmly execute a shot - start draw and. . . . whoosh! Arrow gone.
I think, as Fred Bear said, my eye was triggering the shot before my mind could control it. Or, perhaps more accurately, my eye overpowered my ability to control the shot, and despite many, many efforts to regain control, I was never successful on a lasting basis.
Here's how I shoot now: Face target and look at it without focusing on a specific spot; then draw; anchor, pick a spot and focus on it until the arrow is gone.
I think that my first approach to shooting was more "natural" or "instinctive," and I'm sure that it is better for hunting, but I strongly suspect that it carries the risk of the panic.
As I've said, I reached a point of either quitting archery or changing hands, and I chose the latter and wish I'd done it years ago. I don't shoot as well as I before succumbing to the panic and it doesn't feel "natural," but I control the shot . . . at least for now.
Good luck to all who suffer from the panic.