Quantum mechanics is just a theory based on a lot of conjectures. I love this topic myself but i don't think it has any relevance with this particular subject.
This study is completely generic, first of all, they gave a limited amount of options, which makes the entire free will concept null, it is not completely free if you restrict access to a limited amount. Second, the scans were made only on the frontopolar cortex, which they think it might be the brain region where decisions are initiated.
Let's say they're completely right and decisions are always made 10 seconds before you're even aware of it. How or why are you different from others? How do you explain a person who changes its mind, how do you explain someone learning from their mistakes and making different decisions over time? My point is: even if it is just your brain taking the decisions, it is still free will, every brain functions differently, and there are no identical minds.
Our sub-conscious is a great part of us, it is call that way because you are not 100% aware of everything. In fact, plenty of studies have proven that in a conversation, the body language communicates more than 50% of what you're saying/listening and most people aren't aware of it.
Quantum mechanics are very relevant to the subject. If determinism is correct and everything that has ever happened and will ever happen has already been established, free will, by principle, cannot exist. Now, if indeterminism is correct, the options broaden. Some would undoubtedly end in free will existing, but it could also mean that free will doesn't exist if an event is just the result of quantum randomness. But, as I said, our knowledge of quantom mechanics is very, very limited and giving a definitive answer through it is not possible at the moment. And it probably won't be possible any time soon. But if a definitive answer to this question is to be given, I'm sure it must be and will be through quantum mechanics.
Now, to the study. The scans weren't made only to the frontpolar cortex, it was a whole brain scan. What is said in the article is that the signals
originated in the frontpolar cortex. And not also that, by reading the scans the scientists were able to accurately predict what button the subject would press.
Well, if having a limited amount of options nullifies the concept of free will, there would be plenty of instances in life where there would be absolutely no free will. You may restrict it but not nullify it by what you're saying. There are options and you may choose between them, it may be restricted, but it would still be free will. If we reduce it to the absurd, there would be absolutely no need to study for a multiple exam test because we are limited to a number of options, therefore there is no free will, therefore I have no control over the answer I'll pick. Again, this is just a reductio ad absurdum. If free will is argued to exist, it must be a constant. It needs to exist at all times.
Getting a bit more metaphysical here, but, wouldn't the participation of consciousness in decision making be required for free will to truly exist? If a decision we take is merely electric signals in our brain very much like a computer, how much are us, as a person, involved in that?
How are we different to others? Biologically, our brains aren't exactly the same. they are hardwired differently, different paths will lead to different decisions. Also, the influence of the medium and our experiences mold us differently, that's what makes us unique.