Tuesday, November 9, 2010

Blood and Stakes....

I got the latest copy of the “Journal of Neuroscience, Psychology and Economics” (www.apa.org/pubs/journals/npe) a few days ago. This journal covers the burgeoning field of neuroeconomics or as the journal puts it “the application of psychological and/or neuroscientific methods to business and economics”.

The first article was interesting. “Medial Frontal Activity in Brand-Loyal Consumers: A behavior and Near-Infrared Ray Study”. The authors were Ching-Hung Lin, Hsu-Ping Tuan and Yao-Chu Chiu . This study measure blood flow in the front bit of the brain (hey, let's not get too technical here) when respondents who were defined as brand loyal and brand “switchers” were shown luxury and non luxury items. I never thought I would see “fashion experts” cited like this in a journal. The stimulus materials were handbags. There were a couple of interesting things about the experiment. First they were measuring blood flow by shining very bright near infrared light on peoples foreheads and measuring the reflected light. Think about those things they put on your finger to measure pulse and blood oxygen in hospital. It is that principle but used on the front of the brain, apparently the light can go deep enough into the skull to penetrate the brain. They found that according to the blood flow there was a discernible difference between luxury preferred brands and generic unattractive brands.

What is very interesting is that this uses something you put on a subjects forehead. You don't need a $2-3 million fMRI set up to measure the blood flow at the front of the brain (so the authors say anyway). If this technique really works we can finally put a well deserved stake in the heart of fMRI studies. Using a MRI machine is expensive as well as being very noisy and claustrophobic for the subject. It is impossible to see how the respondents in a MRI are in the correct frame of mind for the results to be valid.

While we are “staking” neuromarketing methodologies, the whole “brain waves with a single electrode on the forehead” needs a couple of stakes through its heart as well. Unless the laws of physics have changed, I am utterly skeptical that you get anything other than muscle noise from the muscle on your forehead, called the Frontalis muscle. My belief that you can get any electrical signals from the brain with this single electrode on the forehead is up there with my belief in Father Christmas, the Tooth Fairy, the Easter Bunny and honest politicians. Really, you have to be kidding me. I don't care how many signal filters you have and how much Fourier analysis you do.

Going back to the handbag paper, yet again we get the usual problem with neuromarketing studies. The authors state that the infrared detection technique they use is “easy to prepare and portable unlike most other brain image instruments”. Very true, a MRI machine is as portable as a small building can be. So given this portable, easy, non invasive, stress free technology they are using how big a sample do they use ? The number they came up with was 28, with one of the groups having just 4 (that is four) subjects in it. Four is not a cell size. It's a minimal number for a dinner party, but not for a cell size in a neuromarketing study if you want to be taken seriously. The whole N in neuromarketing is its biggest problem at the moment, as I have said before. I hope this infrared technique works, I hope even more that someone will use it with a decent amount of subjects. No wonder neuromarketing has to endure claims by traditional MR that it is unscientific, it's the N=tiny that does it. Believe me there are some utterly egregious abuses of statistics and sampling in traditional MR that could be discussed if I wanted to spend the rest of my life being sued. Traditional MR talking about a neuromarketing study not being “scientific” is incredibly hypocritical and they know it. But as long as we have cell sizes of 4......


  1. Some pithy comments in this article: "the whole “brain waves with a single electrode on the forehead” needs a couple of stakes through its heart as well. Unless the laws of physics have changed, I am utterly skeptical that you get anything other than muscle noise from the muscle on your forehead" Ouch.

    Good science and professional practices needs a steady flow of critical thinking, skepticism and "policing." Usually by peers.

    There are more, it's a short read. We are not concerned with small sample sizes. These are basic (universal) biological and physiological processes, whatever sample size medical experiments use is OK with us.

    Methodology is another matter. Lots of missteps there with more to come. Colored outputs usually decrease the value of the information communicated. Our brain's faults, dear brutus.

    One could, in fact, say that large sample sizes to create cells for "ethnicity", SES and geography, etc are just reifying false categories and language artifacts to support pop socio-cultural norms and beliefs.

    If there is not a significant physiological difference -- what's the point?

    Of course, we are radical materialists. If there isn't an individual physiological driver of behavior -- we're not really interested.