The idea that people are influenced by somatic markers—physiological reactions such as skin conductance responses—in decision-making situations, even before consciously evaluating alternatives or forming judgements of the relevant expected utilities. According to this hypothesis, decisions are arrived at through the interplay of two processes, the first deliberative and rational, tending to favour alternatives yielding optimal rewards, and the second largely subconscious, affect-driven, and influenced by physiological reactions that tend to override deliberative decisions involving deferred gratification. The hypothesis was put forward by the US-based Portuguese neurologist and neuroscientist Antonio R. Damasio (born 1944) and two colleagues in a book chapter in 1991 and developed further in Damasio's book Darwin's Error: Emotion, Reason and the Human Brain (1994). According to Damasio, somatic markers are controlled by the ventromedial cortex. See also Iowa gambling task. SMH abbrev.