Somatic markers, conscious knowledge, and decision making on the Iowa Gambling Task

Damasio’s somatic marker hypothesis maintains that decision making is biased by emotional and visceral representations acquired through past encounters with similar choice situations. Using their Iowa Gambling Task, Bechara et al. (1997) claimed that somatic markers, as indexed by skin conductance responses, influenced decision making before knowledge about the decision environment could be consciously expressed. However, Maia and McClelland (2004) challenged this finding claiming the earlier methods used to assess participants’ knowledge were inadequate. More detailed questioning revealed that participants have knowledge of the choice environment much earlier than claimed by Bechara et al., challenging their account that somatic markers operate as nonconscious biases on behaviour. However, Maia and McClelland’s (2004) study included no physiological data leaving open the possibility that changes in somatic activity still emerge before knowledge can be expressed. To address these issues this study replicated Maia and McClelland but included physiological recording. Like Maia and McClelland, we found no differences in gambling task performance between question groups; and participants’ knowledge of the task contingencies was revealed earlier when probed using detailed questions. However, different anticipatory skin conductance activity was found between groups. The possibility that somatic markers do not inform decision making will be discussed.