Some years ago, I lived by myself for the better part of year in a small tent by the river in which the nearest modern conveniences, people and town were approximately six miles around the mountain. The longest I went without any human contact was three weeks and although I was not ready to go off the deep end, I noticed many psychological changes in myself and had a deep need to interact with other people. However once I went and visited in town for a couple of days, I was ready to go back to my solitude but never again did I go for so long without being around any people...I really believe that people need to be with other people if even only for short time frames to help keep their psychological well being in order.

Oh, I'll agree that weeks with NO human contact (including electronic) WILL make you strange. But 3 days? Like I said, if I', in my usual "stressed out NYer" mode, after 3 days I'm just getting to the point where I'd want to casually see someone. By the end of the week, I'd want someone to talk to for an hour or so

The first 3 days? Probably spend somewhere between 30-35 hours of the 72 asleep, 9 cooking/eating/cleaning up, a much curled up with a good book, the rest, chores etc, and if I had access to the great outdoors (particularly the woods) time on walks/sitting in the woods, just watching/listening

when i was working at the Vets Hospital i did a lot of two week solo canoe trips to try and decompress from the stress..
i once went seven days without seeing anyone..thats no canoes far away across the lake..no overflights by the park service..no one on the carrys..at three days it was nice--by day five i was looking around and by day seven i camped at a portage in the hopes of meeting someone--midday day eight i found a lake with people and camped at lunch time just to be around someone---you really do let your mind run to odd stuff wondering if anyone else is out there--

I think one has to take into account that it only took Tom Hanks 3 days to go a little loony in the movie is plot progression. There was only so long the movie would have been able to reamain interesting with him just puttering around the island.