fMRI: Legilimency for Muggles?

(Image from http://www.popularmechanics.com/science/health/nueroscience/4226614)

This past week I have been reading Brainwashed: The Seductive Appeal of Mindless Neuroscience, by Sally Satel and Scott Lilienfeld. In essence the authors caution the reader to consider the limitations of functional Magnetic Resonance Imaging (fMRI) and its seductive color pictures showing how the brain lights up under different stimuli. The use and misuse of fMRI is pervading many fields outside of neuroscience: advertising/marketing, lie-detection tests, morality/ethics, and how-to-make-yourself-smarter schemes.

One of the recent well-publicized studies by Lindstrom and colleagues was to observe the brain activity of subjects while exposing them to stimuli from an iPhone. (You can read Lindstrom’s NYT Op-ed here.) The fMRI results suggested a match with areas of the brain “associated with feelings of love and compassion” rather than addiction. This made for great media headlines, i.e., that you do indeed truly love your iPhone.

Some of the wilder claims suggest that fMRI could potentially be used to read minds. Expose minds to lots of different kinds of stimuli. See which areas light up. Enter this into a large database. If your database is large enough and can discriminate among areas and strength of stimuli, you can now make use of it to interpret subsequent fMRI scans. This reminds me of Legilimency in Harry Potter and the Order of the Phoenix.

When Professor Snape first describes Legilimency, he refers to it as “the ability to extract feelings and memories from another person”. “He can read minds?” Harry Potter blurts out. Snape then retorts that Harry has “no subtlety” and “[does] not understand fine distinctions”. Like Satel and Lilienfeld, Snape cautions against the simple interpretation. “The mind is not a book, to be opened at will and examined at leisure” Snape says, adding that it is also “a complex and many-layered thing”.

Snape then goes on to say that “those who have mastered Legilimency are able, under certain conditions, to delve into the minds of their victims and to interpret their findings correctly”, that the “Dark Lord always knows when someone is lying to him”, and that “only those skilled at Occlumency are able to shut down those feelings and memories that contradict the lie”.

In one of the chapters of Brainwashed, Satel and Lilienfeld describe the use of BEOS (brain electrical oscillations signature) tests to determine if someone was lying or concealing evidence. The standard polygraph lie-detector can be beaten using a variety of measures. Nor is there any surefire way to detect lying accurately and consistently while eliminating all false positives and negatives. This has not stopped entrepeneurs from marketing the use of fMRI as a lie-detector among other things.

What does fMRI actually do? It measures the change in oxygen concentration and blood flow. These are used as proxies to measure brain activity. Where do the pretty colors come from? First, the brain baseline activity needs to be measured – the subject tries to keep their mind as blank as possible. (Sounds like the first step of Occlumency to me!) When the subject is then engaged in a particular task, shown images, listening to sounds, etc., brain activity is measured again. The baseline activity is then subtracted from the task activity by a computer program, which also filters out background noise and then maps a color-coded image on to a “brain template”. Brighter colors typically refer to larger differences between the task and baseline activities. A final image typically comes from the average results from a group of subjects.

One important thing to note is that fMRI represents the neural correlates of a particular task in terms of changes in oxygen concentration and blood flow. fMRI does not tell you that a single specific area of the brain is responsible for a certain specific task. Many areas light up for a given task. Similar areas may also light up due to different tasks. There is no one-to-one correlation between brain activity and a measured task, image, smell or sound. Reverse-inference, trying to predict what someone is thinking based on these signals, is fraught with difficulties.

Phrenology was a common practice 200 years ago where head-shape “experts” looked at the small hills and holes of the skull to predict characteristics and traits, and perhaps even hidden talents and dispositions. Is fMRI the new phrenology? It’s perhaps too early to tell. The authors certainly caution the reader to “entertain some healthy skepticism” when reading a news headline proclaiming that “Brain Scans show” whatever it is being purported.

In the meantime, it is unclear that Muggles will have the ability to become capable Legilimens anytime soon. As to being an Occlumens, well, crooks and swindlers have been practicing it for millennia.