Decision Making Research
A new paper published by researchers in CMU?s psychology department challenges a widely-believed theory: the somatic marker hypothesis. This hypothesis states that decision-making is influenced by somatic markers: bodily states that correspond to emotional reactions. According to the hypothesis, these somatic markers can act subconsciously to guide decisions in the absence of conscious knowledge. This theory, posited by neurologist Antonio Damasio in the mid-nineties in his international best seller, Descartes? Error: Emotion, Reason, and the Human Brain, has become very popular.
Researchers in the psychology department have challenged this theory by examining the evidence that supports it. Tiago V. Maia, a doctoral student, and James L. McClelland, the Walter Van Dyke Bingham Professor of Psychology and Cognitive Neuroscience, analyzed a study performed by Damasio and his colleagues. In this study, Damasio and colleagues sought to demonstrate the existence of somatic markers by having participants play a game. While the subjects were playing the game, the researchers measured their skin conductance and asked the subjects open-ended questions such as ?Tell me all you know about what is going on in this game.? Combining an analysis of participants? behavior, their responses, and their skin conductances, Damasio found that participants would often choose an advantageous strategy before they could articulate why. Their skin conductance would be different when choosing between the strategies, showing that the participants had somatic markers that were guiding their decisions based on subconscious information about the goodness or badness of each strategy.
According to Maia, this study had a number of methodological flaws. In particular, the way conscious knowledge was assessed was suspect: ?There is good evidence in the literature that the use of such broad questions often fails to uncover all of the knowledge that subjects actually have. When answering this type of question, subjects may not tell you everything they know because, for example, they aren?t sure of their knowledge, they don?t know exactly what to say or where to start, or for many other reasons.? This raises the possibility that the subjects knew the advantageous strategy before acting advantageously. In order to better understand what the subjects knew, Maia and McClelland performed a similar experiment. This time, though, as Maia put it, they had a more thorough test of what people knew when they were playing the game.
By using this more sensitive test of conscious knowledge, Maia and McClelland showed that individuals may have been acting upon knowledge and not bodily states. The researchers look at other evidence that supported the somatic marker theory and found that in all cases recent results suggest alternative interpretations for evidence that do not involve somatic markers.
Having undermined the foundation for the somatic marker hypothesis, the researchers have not outright rejected it. The conclusion of their paper states: ?Even though our findings, together with these other findings in the literature, do not prove that the somatic marker hypothesis is wrong, they do undercut virtually all sources of support for it. For the somatic marker hypothesis and, more generally, the theory of decision-making originally proposed by Damasio, to remain viable, new evidence to support it must be produced.?