detail the vast bulk of people are reticent about having their sexual activity observed by others. That such an attitude is not innate is shown by various cross-cultural studies. Any effective scientific project, involving direct observation of human coitus, has to begin by overcoming the reticence in people about having sexual intercourse in public. In a number of small scale projects this was accomplished but it was not until the work of William Masters and Virginia Johnson that the taboo was effectively combatted for hundreds of men and women.