How does awareness influence information processing during decision making in the human brain? A new study led by Floris de Lange of the Donders Institute for Brain, Cognition and Behaviour at Radboud University Nijmegen, offers new insight into this question.
When making a decision, we gather evidence for the different options and ultimately choose on the basis of the accumulated evidence. A fundamental question is whether and how conscious awareness of the evidence changes this decision-making process.
The researchers showed that while we are able to accumulate evidence, the level of awareness led to marked changes in decision making, both in terms of brain activity and behavior. Crucially, evidence accumulation changed from a linear to a non-linear integration strategy with increasing level of awareness. Specifically, the impact of later evidence was reduced when more evidence had been accrued, but only for clearly visible information.
De Lange and colleagues show that evidence of which participants are hardly aware is processed ‘automatically’, with all incoming information being treated equally. However, when subjects are clearly aware of the evidence, the weight of new information is modulated depending on what they already know.
Citation: De Lange FP, Van Gaal S, Lamme VAF, Dehaene S (2011) How Awareness Changes the Relative Weights of Evidence During Human Decision-Making. PLoS Biol 9(11): e1001203. doi:10.1371/journal.pbio.1001203