Experimental tests of the Somatic Marker hypothesis

Damasio's [Descarte's Error: Emotion, Rationality and the Human Brain. Putnam (Grosset Books), New York, 1994] Somatic Marker hypothesis posits that emotion-generated mental markers influence our decisions and, in particular, tend to curb inherent tendencies to seek risk, to be impatient and to be callous in social situations. Ventromedial (VM) prefrontal cortex damage interferes with this marking process, resulting in risk seeking behavior, impatience and socially inappropriate behavior. In the present study, we present 27 normal controls and 17 patients with prefrontal cortex lesions with batteries of questions designed to probe their attitudes toward risk, intertemporal preferences and behavior in social contexts. The results demonstrate that VM patients are no more risk seeking, impatient, or prone to behavior in socially inappropriate manners than normal subjects. Indeed, we find no significant differences of any sort between the two groups of subjects on any the dimensions investigated. We discuss why VM cortex damage in humans appears to influence decisions in certain circumstances but not in others.