OG12/126 - Here's the modified sentence : "The use of

Hi Voodoo,

First, you know "that create unconscious physical responses" cannot point to "individual" because

1) you would use "who" instead of "that" when referring to a person.
2) even if you used "who"---the word "create" is for a plural reference, not a singular reference. "Individual" is singular and only "hormones" is plural. So it must be the case that the phrase refers to "hormones."

If you wanted to switch it around so the phrase in that part of the sentence refers to the "individual"---you could say:

"studying produces hormones in an individual who focuses his mental energies for more than 2 hours"

You could also have the phrase in that part of the sentence refer to hormones like it is in the question repeated below:
"studying produces hormones in an individual that create unconscious physical responses.

So in short, you can't always tell for sure. You have to check the MEANING of the sentence. Structurally, it may not always be super clear. You still have to read into the meaning of the sentence and see which one makes sense.

In this case, there were 2 reasons why the sentence refers to "hormones" instead of "individual" and those 2 reasons were numbered in my response above.

Hope that helps!