Is knowing always feeling?

I n a recent issue of PNAS, Maia and McClelland (1) report findings that raise questions regarding the interpretation of a highly influential neuropsychological study of decisionmaking behavior (2). That study has been interpreted widely as evidence that decision-making behavior is governed by emotional factors outside of awareness. The impact of Maia and McClelland’s study is not so much to challenge this idea in its own right, which most sophisticated observers of behavior would acknowledge has potential merit. Rather, it is to set a standard for what counts as evidence of an unconscious influence on behavior or, more accurately, to bring this standard from a long tradition of cognitive psychological research to bear on the rapidly growing field of research into the neural bases of decision-making. Recent years have seen a dramatic surge in research seeking to understand the neural processes underlying how we make decisions and choices. These investigations have been initiated by both behavioral scientists, who have begun to see the usefulness of constraining theoretical models with information gleaned from studying the brain, and neuroscientists, who have become interested in using existing models of decision-making to examine neural processing. Researchers in this growing field have used a variety of methods in their quest to describe how the brain makes decisions, including neuroimaging techniques such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), electroencephalography (EEG), direct neuronal recordings in nonhuman species, and work with braindamaged patients. Among the most inf luential work using the last of these methods has been that of Bechara and colleagues (2–4). These researchers have conducted investigations of the decision-making capabilities of patients who have suffered injury to ventromedial portion of the frontal lobe (2–4). It has long been known, dating back to the famous case of Phineas Gage, that damage to this area of the brain leads to a deficit in certain types of decisionmaking (5). In general, patients with ventromedial prefrontal cortex (vmPFC) lesions exhibit normal cognitive abilities as measured on standard tests of memory, language aptitude, and general intelligence. However, as in Gage’s case, the patients frequently demonstrate poor decision-making behavior, and family members and friends often complain of something amiss in the patient’s postinjury personality (6). The patients are described by phrases such as ‘‘emotionally f lat,’’ ‘‘decides against his best interest,’’ ‘‘doesn’t learn from his mistakes,’’ ‘‘is impulsive,’’ ‘‘decisions lead to negative consequences,’’ and so on. Although these are useful observations, as yet it has proven difficult to convert them into firm behavioral and theoretical concepts.