Singular vs plural form
I am reading an article about neuroscience and these few sentences are bothering me. I am not sure if there is an error or it is just me having some internal conflict :D

the author is using "their brain" while there is "a participant" or "an individual.

What do you guys think about it?

..Not only that, it’s only matter of time before they(the scientists) are able to tell each individual’s set of aptitudes and shortcomings, simply from scanning their brain.

Researchers in this study could accurately predict how a participant would do on the test by scanning their brain with an fMRI.

Question

Singular vs plural form
I am reading an article about neuroscience and these few sentences are bothering me. I am not sure if there is an error or it is just me having some internal conflict :D

the author is using "their brain" while there is "a participant" or "an individual.

What do you guys think about it?

..Not only that, it’s only matter of time before they(the scientists) are able to tell each individual’s set of aptitudes and  shortcomings, simply from scanning their brain.

Researchers in this study could accurately predict how a participant would do on the test by scanning their brain with an fMRI.

Answer

Good question. The history of this issue is that "their" and "them" have come to be used as more space-efficient and practical alternatives to, "his or her" and "s/he", respectively. For a long time there was resistance within the professional writing community to using "their" because, of course, its plurality is wrong, as you noticed. :) But in time that objection was overcome, and now it's standard practice.

and this few sentences -> and these few sentences