Intuitive decision making in complex situations: somatic markers in an artificial grammar learning task.

In this article, we explore the extent to which implicit learning is subtended by somatic markers, as evidenced by skin conductance measures. On each trial, subjects were asked to decide which "word" from a pair of "words" was the "correct" one. Unknown to the subjects, each "word" of a pair was constructed using a different set of rules (Grammar A and Grammar B). A (monetary) reward was given if the subject chose the "word" from Grammar A. Choosing the Grammar B word resulted in (monetary) punishment. Skin conductance was measured during each of 100 trials. After each set of 10 trials, the subjects were asked how they selected the "correct word." Task performance increased long before the subjects could even formulate a single relevant rule. In this preconceptual phase of the experiment, skin conductance was larger before incorrect than before correct choices. Thus, it was shown that artificial grammar learning is accompanied by a somatic marker, possibly "warning" the subject of the incorrect decision.