Boing boing pointed to this New Scientist article showing measurable changes in brain function under hypnosis. It is described as significant because it shows that hypnosis is not just a parlor trick performed by stage magicians. But it has long been recognized that it is a truly altered state of consciousness, so it should surprise no one that it produces frank alterations in brain function. Readers of FmH will know that I am enamored of and tend to link to functional MRI studies that show which brain regions are active during particular cognitive tasks. For me, the accumulating evidence of localization of a given cognitive function is much more important than what I consider the trivial finding that brain function is altered when you perform the task. Yeah, so?

I haven’t read the research paper but the New Scientist article doesn’t describe the experimental design in enough detail to help me understand hypnosis any better. It does not even describe the nature of the cognitive taks that was used, called the Stroop test. Here is a link to a description of the Stroop, which essentiallly involves being given a list of color names printed in colored ink. A given word is printed in a color different from the color it names; for instance the word “blue” may be printed in orange. The test is a measure of a person’s ability to operate under conditions of cognitive interference, in that you must name the colors of the words successive cards without reading the words. It is not as easy as you think. In the current fMRI study, subjects performed the Stroop test first unhypnotized, and then again hypnotized; the performance of ‘suggestible’ (easily hypnotized) subjects was compared with those who were less susceptible to hypnosis. The susceptible group showed greater activation in the anterior cingulate gyrus and the left prefrontal cortex when performing the task under hypnosis. The New Scientist article does a further disservice of making some pat pronouncements about what these two implicated brain regions ‘do’. In fact, just as the cognitive changes in hypnosis are quite abit more complicated than you think, so too are the information-processing roles of these brain regions.