Thanks for the kind words and suggestions for further testing. One of the further explorations coming from this research is dropping the valid indicator altogether but that does not help with difficult inputs where validation helps people a lot. So instead we considered changing the format /text of the indicator to something more like “that’s a valid answer” vs. “thats a corect answer”. Small difference but important.
We didn’t place the checkmarks to the left of inputs because of the varying message sizes for error states: “too short, taken, valid, not secure, etc.” the different kinds of messages need some room to be displayed hence to the right of the inputs where they can scale. If we only did images/icons and no text -that would be an option, but then you get no help in remedying errors other than “there is an error here”.
Not sure how a “while” could be used for only invalid fields? Do you mean after a user leaves a field in an invalid state and then comes back to it?
You can format inputs after user input (or sometimes even while) but you shouldn’t change the content of their input to make it valid in the vast majority of cases. Here’s an example of the former using Input Masks: http://www.lukew.com/ff/entry.asp?756