My Brain Made Me Do It!

I couldn’t stop thinking about the idea of the “amygdala defense” that came up in “The Emotional Brain Revisited” chapter of LeDoux’s book. LeDoux’s research is largely focused on emotions and how the brain responds automatically to emotional stimuli. Scientists have identified the amygdala as a key player in controlling anger and fear and lawyers have tried to exploit this knowledge to use it as the ultimate courtroom defense. LeDoux has been asked by lawyers to help put together an “amygdala defense” to show that their client’s crime was not based off of free will but rather the fault of a small almond-shaped part of the brain that we call the amygdala. A few weeks ago Jess wrote a blog post on using the brain as a defense in the courtroom (involving a man with a brain tumor that pressed on his amygdala who ended up going on a killing spree), but I wanted to go a little further.

Last class we briefly debated whether it would be appropriate to use brain scans in court to tell if people are lying—a modern lie detector. I don’t have a problem with this idea in theory, what’s wrong with a more accurate lie detector test? The issue is, is that I don’t think that it would be more accurate. I don’t buy that the scans can tell us whether someone is lying or not in the first place. Hyperactivity, or inactivity, in a certain part of the brain can mean different things and doesn’t actually say something in and of itself. The amygdala, for example, is involved in other processes besides fear and anger and any activity in this area could hypothetically mean a plethora of different things.

Having this discussion inevitability means that we have to talk about free will and determinism because what we are really asking is, should people be held accountable for their actions? Determinists posit that everything that will happen in our future is by prior actions, meaning that what we do is inevitable and is out of our control. For many of us, this idea is hard to wrap our heads around. I like to think I make my own decisions (especially when they are good ones!) and so it’s almost impossible for me to believe that what I do is just a result of electrical signals in the brain. This is my belief even though I know that neuroscience research demonstrates that the brain largely runs on autopilot. If we accept that the brain does run on autopilot, then how much responsibility can any one of us assume? It seems like a great defense for a killer: “my brain made me do it!” And guess what? People’s brains do make them do things but that’s not to say that these actions weren’t based off thought-out decisions. My biggest problem with the argument is that it only seems to apply to crimes of passion (besides in the case of a tumor maybe). Most murders are premeditated and how can a surge of hyperactivity in part of the brain like the amygdala account for a planned murder? Such crimes are certainly not impulsive.

Michael Gazzaniga, the famous neuroscientist, is coming out with a book that looks at this predicament called, “Who’s in Charge? Free Will and the Science of the Brain”. In a recent New York Times Article he says that brain science “will eventually begin to influence how the public views justice and responsibility”. I think that this is already happening. Gazzaniga does not believe there should be a brain defense and I agree. I believe that responsibility is still in the hands of individuals. This becomes tricky because if reasoning and responsibility are functions of our mind, then isn’t this still implicating our brains? Gazzaniga has an answer to this and says that ‘Like generosity and pettiness, like love and suspiciousness, responsibility is what he calls a “strongly emergent” property — a property that, though derived from biological mechanisms, is fundamentally distinct and obeys different laws, as do ice and water.’

So what do you think? Are we committing crimes or are our minds the real perpetrators?



6 thoughts on “My Brain Made Me Do It!

  1. This is the issue: Over 1,000s of years we have discovered that a decent civilization is predicated on security of a person and their property (and many other things).
    When we move away from these two principles the result is catastrophe and we can see this consistently in peace and at war.
    If people inclined to deprive people of their “freedom” in these matters we sanction them one way or another. Under some circumstances they may be rehabilitated, expelled, imprisoned or executed.
    Whether they are “responsible” or not is not relevant. The cause of the sanctioned action is a worthy research topic with an eye to prevention but rehabilitating or excluding offenders is an achievable goal.
    The Courts should establish the facts of any matter to the greatest degree possible and judgement made on that basis.


  2. This made me think of Charles Whitman, the mass murderer who, in his suicide note, requested an autopsy of his brain to see what was causing his irrational and disturbing thoughts. What they found was a tumor that I think was pressing on his amygdala. Cases like this could complicate matters if we were to start using the brain as an “excuse” for crime


  3. Reesa, this is super interesting! I agree with Robyn that cases like Charles Whitman’s allow the brain to become an “excuse” for the crime. I know we’ve all heard of plenty of cases where the criminal is declared innocent to an extent because of a pre-existing emotional or neurobiological condition. Instead of jail time, they receive therapy. That doesn’t seem fair to me. The brain shouldn’t be an “excuse.” They still did the crime, so shouldn’t they be punished?


  4. I also like your point about the potential flaws of a brain-scan lie detector test. We are definitely not at a point where we can read scans accurately enough to say whether or not someone is lying. If increased heart rates due to being nervous can trick a regular polygraph into showing false positives, it seems possible that a similar thing could happen in our brains.


  5. Some mysterious unnamed Neuroscientist just made a post (entitled “The Brain and Sexual Assault?”) talking about this and I feel like it could do with a little of that context.

    My personal opinion, which I think that argument supported, is that only in extreme cases is brain morphology a legitimate excuse for breaking the law. It’s a heck of a question, though, and there are so many weird cases that it would be hard to get a good rule of thumb for what stuff counts as being a medical excuse; after all, everything you do begins in your brain, and it’s hard to separate the beneficial and detrimental effects of gross anatomical changes.


  6. haha, whoops i was the mysterious unnamed Neuroscientist. Anyways, even if a person has a brain tumor or whatnot, they still are a threat to society. The reason we put people in jail (or a mental asylum I suppose) is not for punishment, but also to prevent them from hurting others or themselves.

    Derek, I like your point that everything comes back to the brain, and I think LeDoux would agree! If our brain is what makes up our selves and influences are behavior, than isn’t everyone’s brain that causes them to commit crimes?

    Whenever I think about these topics, I always think of one flew over the cuckoo’s nest, in which McMurphy claims insanity to avoid prison time. In the book, he is examined by psychiatrists in order to determine whether he is mentally ill or not. However, there have been a significant amount of changes in treatment of mental illnesses since the book was written (for example, we don’t usually use electric shock therapy anymore)…


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