In a study, participants listen to either:
A list of 19 famous women and 20 less famous men
A list of 20 famous men and 19 less famous woman
Afterwards, some were asked to recall the names they could remember, and then if the list they had heard contained more men or women.
Unsurprisingly, the famous names were more readily recalled; but, interestingly, the vast majority of participants then incorrectly assumed that the gender of the more famous people were the majority gender in the list they heard.
This is an example of the Availability Heuristic.