There are two key differences between walking outside in public and disclosure on Facebook: a) In public, observation is reciprocal (that is, you can see who i

There are two key differences between walking outside in public and disclosure on Facebook: a) In public, observation is reciprocal (that is, you can see who is watching you) -- less universal in these days of CCTV, but traditionally this has generally been the case, and b) Public observation is real time and line of sight; FB "observation" may take place days, months or years later by persons you have never had an opportunity to see. The long term consequences arising from these new constraints are not yet obvious.