Could someone please help me understand what this sentence means?

It is saying that people that are treated a certain way due to stereotypes, begin to behave in a manner that conforms to that stereotype. It isn't any different than the person that constantly gets accused of being a certain way, then decides to act out on the accusation even though they hadn't up until then. It is actually a very common human response.

It is condemning doctors or others in the medical profession, who are not sufficiently open minded when making a diagnosis, wrongly recommending treatment which in turn convinces the patient that he has the complaint for which he is being given this treatment.

It reminds me of someone I used to know who threw a sickie when he was not really ill and remained on sick leave for several weeks. When he got fed up of being idle he went to the doctor to sign him off as fit for work but the doctor found him unfit for work and would not sign him off.

It means that if you treat the person as a stereotyped disabled person, they will start living the stereotype. Like if you tell a person with a spine injury they will never walk again, they will not try or do the physical therapy that might allow them to walk. Another example is, kids with learning disabilities, if called dumb, will stop trying to learn.

One interpretation is that, if we look at persons with visible disabilities as being incapable of ______ (whatever), it is likely that, given the opportunity to do _____ (whatever), these persons will prove themselves incapable. It is not because they really can't, but it reflects the bias inherent in the stereotype that a disabled person is incapable.

If you are called "Disabled" you might think yourself into a "disabled" state of mind. That then makes it easy for the "caring professions" to treat you as "Disabled" (without necessarily thinking of you as a person with individual needs).

IT MEANS THAT PEOPLE LIVE UP TO STEREOTYPES COMMONLY USED ABIUT THEM....OR I SHOULD SAY...LIVE DOWN TO.