Fear: Across the Disciplines

2. THE BIOLOGY OF FEAR: EVOLUTIONARY, NEURAL, AND PSYCHOLOGICAL PERSPECTIVES

35 Arne Öhman FORMER U.S. PRESIDENT George Herbert Walker Bush and federal funding agencies dubbed the 1990s the Decade of the Brain.1 Indeed, thanks to an increase in funding and publicity there was a rare explosion in knowledge and research techniques about what is conventionally called “higher nervous activity.” Partly as a follow-up, partly out of a concern that other aspects of brain activity had gotten short shrift during the so-called Decade of the Brain, and partly to shift attention back to the Decade of Behavior (2000–2010), a group of leading U.S. scientists in 2007 published a manifesto in Science, demanding a Decade of the Mind for the years 2010–2020. The premise for this initiative of scientists from disciplines as varied as cognitive science, psychology, neuroscience, medicine, computer science, engineering, and mathematics is that “a deep scientific understanding of how the mind perceives, thinks, and acts is within our grasp”; the initiative further proposes that “research should be encouraged on all aspects of the mind believed to be uniquely THE BIOLOGY OF FEAR EVOLUTIONARY, NEURAL, AND PSYCHOLOGICAL PERSPECTIVES 2 36 Arne Öhman human, such as the notion of self, rational thought processes, theory of mind, language, and higher order consciousness.”2 Emotion is part and parcel of “how the mind perceives, thinks, and acts.” Our understanding of emotion, and particularly the emotion of fear, has been revolutionized during the last couple of decades. Before research on fear gets another boost during the Decade of the Mind, it makes sense to take stock and survey what has been done so far. The purpose of this chapter, then, is to present the current knowledge of fear in psychology, neuroscience, and the theory of evolution. The chapter is organized topically around a number of propositional statements about fear, some of which are primarily conceptual and theoretical, while others grew out of empirical research. FEAR IS AN EMOTION Fear is a state that is all too familiar to many of us. Fear is an emotion —few would argue with this proposition. But what kind of emotion? According to one contemporary definition of emotion, they “are multicomponent responses to challenges or opportunities that are important to the individual’s goals.”3 A “multi-component response” in this context refers to components of feeling (conveyed through verbal reports), bodily activation (e.g., heart-rate changes), and behavior (e.g., approach or avoidance). Fear is the paradigmatic emotion evoked by challenges perceived as threatening. The dominating feeling of fear is an intense urge to get out of the situation.4 Thus, flight is a dominant behavioral response to fearful circumstances, and because it taxes metabolic resources, fear typically includes an activated body. In humans, flight does not have to mean “running away”; it can also occur on a symbolic level, as in attempts to evade a disturbing thought by trying to focus attention on something else. FEAR IS FUNCTIONAL Many of us would prefer a life with much less fear because we perceive most of the fear that we experience as irrational, as limiting our choices, and as detrimental to our well-being. Indeed, a hallmark of anxiety disorders, which may afflict up to 25 percent of human populations, is that they involve fear that is out of proportion to the objective danger of the situation. Nevertheless, in a broader perspective fear is functional: it is deeply rooted in biological evolution.5 The primary function of fear The Biology of Fear 37 is to foster coping with stimuli that are perceived as dangerous in a psychological or physical sense. Fear is predicated on a perception or a belief that something can be done about the situation, and it motivates coping behavior that is appropriate in view of this perception. Fear, if you will, includes an element of hope. If nothing can be done to alleviate the threat—in situations of helplessness—fear turns into a different emotion that is best termed “anxiety.” The Evolutionary Origin of Fear The pillar of biological evolution is the transport of genes across generations . Hence our preoccupation with procreation: partners, sex, pairbonding , children. But to enjoy these delights we must survive in often hazardous environments. Microorganisms can invade us, substances mistaken as nutritious can poison us, predators can attack us, we can drown in water, get crushed by falling rocks and trees, burned by fire, or caught in avalanches, and last but not...