Clinical Psychology Tests: Anyone who knows about these things PLEASE answer this question?

Is it true that Black people are not able to do certain tests that involve using head gear needed to read neurological waves?

The reason why I ask is a public academic institution has a lab for the psych department and every year they do a study on social behaviour based on gender, race, age, program of study, and career interests. I have had friends sign up later to be stated they didn't qualify by the lab manager via email. They gave them vague responses saying the study is only for specific groups in one instance, than later saying their hair type won't give good results regardless if its straightened, long, short, braided, or curly.

I find this questionable and fishy, because I highly doubt through history no blacks have ever been apart of neurological tests -_-. Mind you I attend a very well recognized university and this is one lab out of many labs in different fields were studies have been done on all races including blacks. The lab manager sent emails stating she couldn't disclose the group criteria it would compromise the hypothesis EVEN though the study did not advertise for certain groups be a general study for male and female students.