Reading Brain Scans for Intention Identification: A Tale of Two Anthropologies

摘要

On February 8th, 2007, the Max Planck Society released a statement summarizing the results of a study1 headed up by neuroscience researcher, John-Dylan Haynes. According to the report, the Haynes experiment demonstrated "how and where the brain stores [a person's] intentions." The study's conclusion-"that spatial response patterns in medial and lateral prefrontal cortex encode a subject's covert intention in a highly specific fashion"~2-followed from an experimental design involving eight human subjects, all right-handed and with normal or corrected to normal vision. The participants' brains were scanned using magnetic resonance imaging (MRI)~3 while the subjects were instructed (1) to decide (a) whether to add or subtract numerical figures that would eventually be supplied and (b) to hold that covert intention for a variable number of seconds; (2) to carry out the chosen task after two 2-digit numbers were presented on a screen; and (3) to indicate which task they had chosen by pressing the button corresponding to the correct numerical figure for the respective addition or subtraction task they had decided upon and performed. With the coupling of functional magnetic resonance imaging (fMRI)~4 to sophisticated decoding algorithms, the researchers were able to decipher the structural and functional neural correlates of the various participants' covert addition/subtraction intentions with 70 percent accuracy.