Decisions and outcomes
There were two main reasons why we decided only to recruit men for the study.
First, we wanted to be sure that our results would be comparable with findings from previous research (in particular, the Stanford Prison Study). If we had included women as participants and obtained different results, it could be argued that this was simply because, unlike previous researchers, our participants were female.
Second, we were motivated to try to minimize the risk of harm to participants. There would be obvious ethical issues associated with locking men and women up in the same cells.
This is not to say that studying women would be uninteresting or unimportant. It would be fascinating. But it is for another study.