https://phys.org/news/2018-09-passwords.html

"Our model could be used to predict the memorability of passwords, measure whether people remember them and prompt password system designers to provide incentives for people to log in regularly," Lindqvist said. "Logging in more often helps people remember passwords."

It's well-known that text-based passwords are hard to remember and people prefer simple, unsecure passwords. The study found evidence that human memory naturally adapts based on an estimate of how often a password will be needed. Important, frequently used passwords are less likely to be forgotten, and system designers need to consider the environment in which passwords are used and how memory works over time.