Choosing Before Awareness of Choosing

Posted on April 23, 2008
Filed Under Philosophy, Science | 5 Comments

Chris over at Mixing Memory has up a great post about fMRI images and predicting behavior. It’s well worth reading if you’re familiar with the old Libet study where the brain decides a choice before we’re aware of making the choice. That study was often quoted but ended up being problematic as it didn’t make a clear distinction between the concepts of deciding and intending. For a great rejoinder to Libet check out Mele’s chapter “Free Will and Neuroscience” in his book Free Will and Luck. (About to be released in paperback a few weeks after I buy the hardcover)

The big question I have is whether these fMRI studies make the same error of conflating deciding and intending. It sure sounds like they do.

Check out this paragraph where Chris summarizes the methadology.

…Haynes et al. (Haynes is one of the authors of the Soon et al. paper) published a paper in Current Biology(3) that’s basically the same as this week’s Nature Neuroscience paper. They asked participants to choose between two tasks (either addition or subtraction), then to “covertly maintain their intention” (I guess that just means keep it in mind, in neuroscientist-speak) during a delay, after which they would be presented with two numbers and the two possible answers (one for addition and one for subtraction), from which the participants were to select the correct one given the decision they’d made.

Since this is an imaging study, participants were having pictures of their brains taken all along, using fMRI. After everything was done, Haynes et al. used pattern recognition techniques to look for, well, patterns in the fMRI data taken during the delay (while participants were covertly maintaining their choice), and then correlate those patterns with each of the decisions. They then used the results of the pattern recognition analysis to predict which of the two decisions a participant had made. Activity in several brain regions were able to predict participants’ choices, including the anterior medial prefrontal cortex, the posterior medial prefrontal cortex, the left lateral frontopolar cortex, the left frontal sulcus, the right middle frontal gyrus, the left frontal operculum, all regions associated with memory, executive functioning (e.g., planning and resource allocation), and motor control. The medial prefrontal cortex had the highest prediction accuracy, correctly predicting participants’ choices 71% of the time. When thinking about this, keep in mind that this activity occurred before people actually carried out their chosen activity, so this is all activation associated with the choice itself. Or so the logic goes.

The problem is that if they are “maintaining their intention” then it isn’t an intention being discussed but a decision. Deciding is much vaguer than intending. I can decide to go to the store but until I set out I’ve not created an intention. This is a real important distinction even if sometimes we use the word “intend” to mean decide.

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Comments

5 Responses to “Choosing Before Awareness of Choosing”

Excellent point Clark. I heard the author interviewed recently, I forget where, I think it was All in the Mind, and I was rolling my eyes the entire time. Too many people think fMRI tells them everything going on in the brain and make all kinds of fallacious leaps. fMRI is a fascinating tool, but we really still don’t have any way of really knowing the inner mind of a person. We are stuck with tempting hints and cues.

2 Rich Knapton on April 27th, 2008 10:11 pm

That all works when you are trying to decide whether or not to go to the grocery store. However, how does that work if you are in the mountains and you hear the rumble and crash of a couple of large boulders heading your way?

Rich

Interesting different take on this class of experiments over at Ends of Thought. His point is that the time that is relevant isn’t the awareness of decision but the awareness of awareness of decision. It’s a good point but I’m not sure it’s the major problem with this class of experiments.

An other post on the topic that is quite in depth about the methodology. Although he doesn’t raise the philosophical issues.

Interesting followup post by someone.

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