Question: How do the PSP's Parental Controls Work?
Tucked away under the PSP's Security Settings is an option called Parental Control. When enabled, Parental Control uses an 11-point scale to restrict what games and movies (whether on UMD or downloaded from the PSN Store) can be played on the PSP system. A setting of 11 allows all content, while a setting of 1 restricts all but the most kid-safe games and movies.
You can set the Parental Controls individually for different accounts on a single PSP system. So if, for example, you set the the Parental Control level to 4 on your child's account, anyone using that account will be able to play games and movies with a Parental Control level of 4 or lower. Users of other accounts will not be under the same restriction.
Unfortunately, games that carry the same ESRB rating don't always have the same Parental Control level, with some simply having no level at all. It's up to the developer/publisher to set this (the same goes for video). It's also quite easy for children to find and change the Parental Control level of the PSP themselves, even if the system has been password-protected. For these reasons, it's best to use the Parental Control setting in conjunction with the ESRB's ratings and your own discretion.
To can find out the Parental Control level for a particular game or movie, insert the UMD (if applicable), enter the Home Menu, navigate to the content under Game or Video, and press the Triangle button. From the sidebar menu, choose "Information." The next screen will show the content's Parental Control level.