Tracking usage of the "go back" function

[dvt@georgetown.edu]

I would like to run an experiment in which participants will first make a choice between a number of alternatives (scale response item) and then, on the next page, will receive additional information. We want to allow participants to go back to their previous choice, if they want to, and change their responses. How can I track who actually goes back and change their responses given the new information?

I'm aware of the "allow go back" option in the questionnaire file but I don't see how to have the usage of this tool recorded in the data file. Is there a way I can accomplish this? Thank you!