A colleague volunteered to assist a PhD student with their research. It involved attending the lab once a day after hours to count out exactly a thousand small ball bearings transferring them one at a time from one container to another. The task was fiddly, slow and boring and after four sessions my colleague just didn't turn up again. This was years ago and he still felt guilty that he may have ruined a students research. But as he said as he had no idea what the research was about it could be that it was to test levels of tolerance to repetitive and monotonous tasks, in which case may be he had helped. He didn't know because he had avoided the student due to being embarrassed about letting them down.
Seems to me the most interesting part of this story was what it said about feeling guilty but doing nothing about it which is surly one of the more interesting characteristics of human behaviour.
Blair McPherson author and blogger www.blairmcpherson.co.uk