Generally speaking, background checks seek to evaluate a handful of items - they vary by company and by amount paid - in some cases they include a credit history, in some they do not.
At a firm they look for a bunch of random things: For instance, you claim to have been working in FL from 2000-2007 but you filed tax returns in Texas. You say you were in school in IL from 1999-2000 but your address shows up in Omaha. Things that are generally inconsistent with your job application. Ideally, this includes degree verification. It likely also includes some attempt to identify dates of employment, position and salary, though 99% of firms I know will not disclose salary at all. In general, they are looking for glaring inconsistencies. If there's a criminal check, typically the kinds of crimes they are looking for are things that would put other people - your coworkers, boss - at risk ....im talking about assault, aggravated assault, battery, aggravated battery, assault with a deadly weapon, manslaughter, murder, rape, false imprisonment, domestic assault, kidnapping, a dozen TROs, etc. Either that or issues of serious ethical breach such as say b&e or embezzlements, RICO act stuff. Credit checks are just a further element of this.
Now for the purposes of grad school, they aren't looking for exact employment dates, nor do they care if your salary is right - some people include bonus, some not, etc. They aren't going to come after you if you are off on salary figures, nor will they come after you if dates don't line up precisely, nor will they likely validate extracurriculars (its near impossible to do, generally theres no public record of that stuff). They are less concerned with these details and more concerned with egregious claims: If you claimed not to have a criminal past and you have a (serious) criminal past, thats not good. If you claimed to have a degree and don't. If you claimed to work at a firm Y and you never worked there at all.
So unless you happen to take the "the" out of psychotherapist, I wouldn't don't get hung up on this background check.