I recently came across a paper by economist Hammad Siddiqi, The Social Norm of Leaving the Toilet Seat Down that uses game theory to describe the efficiency of the toilet seat position strategies normally preferred by men or women. Men in their own habitat will usually prefer to leave the toilet seat in its last-used position to thereby minimize the number of times it must be repositioned for use. Women on the other hand always want it down, since that is the only position that they use it in.
The man-approach to the toilet seat does in fact drastically reduce the total number repositions of the seat, though at the cost to the woman of a small number of repositions. Siddiqi finds that the woman-approach remains the norm however because the cost to the man of the woman’s anger each time she repositions is greater than the effort needed to reposition the seat many times.
From the paper’s conclusions:
For “mankind”, the analysis in this paper has the following appeal: Once again, it has been found that the social norm of leaving the toilet seat down is inefficient; hence, “mankind” may feel vindicated.
For “womankind”, the analysis in this paper is appealing for the following reason: It has been shown that the social norm of leaving the seat down is a trembling-hand perfect equilibrium. Hence, this norm is not likely to go away, at least in the near future.