Articles: Coming to terms with Fear

• Fear


  A conscious experience of those who dislike driving over high bridges or encountering large spiders
• Fear system


  The brain system that detects and responds to threats, distinct from the mechanisms that make possible the conscious feeling of fear
• Pavlovian fear conditioning


  1. Presenting a neutral conditioned stimulus (CS) with a noxious unconditioned stimulus (US)

  2. The CS comes to elicit species-typical behavioral responses and physiological adjustments

  3. Allows researchers to control the antecedent conditions (CS and US) and measure the outcomes (dependent variables)
• Associative learning


  A process that allows the US to alter the effectiveness of the CS in activating circuits that control defense responses in anticipation of harm
• Fear conditioning has many attractive features as a laboratory tool - it is rapidly acquired, long-lasting, and can be used across a wide range of animals
• Behaviorism


  A psychological approach that banished consciousness from psychology, focusing instead on observable events
• Intervening variables


  Psychological but not conscious factors that account for the expression of defensive behaviors in the presence of a threat, without implying unobservable entities
• Drive theory


  The view that reinforcement of behavior during learning results from reduction in a physiological drive state
• Fear as a learned drive state


  The view that fear is a learned drive state that comes to be elicited by the CS after Pavlovian conditioning with a shock US
• Over subsequent decades, much research was done to evaluate the role of fear in avoidance, leading to the idea of central (brain) motive states
• The expression "state of fear" implies the presence of unverifiable feelings in animal subjects, which is problematic for behaviorist researchers
• Fear


  When fear takes on its received meaning as a conscious feeling, and researchers start looking for properties associated with human fearful feelings in animals
• The expression "state of fear," practically begs the reader to think of rats feeling afraid of the CS and to think that this feeling is the cause of defensive behavior
• Researchers who were working in the behaviorist tradition were likely thinking along the lines of empirically verifiable constructs and not in terms of unverifiable feelings in their animal subjects
• A variety of empirically based interpretations of fear were proposed
• Mowrer, a leading figure in this field, explicitly endowed the central state of fear with subjective properties that were said to cause behavior
• Even authors who seemingly adhered to empirically based approaches wrote about fear in a way that could easily be interpreted to mean a subjective feeling
• The word fear would sometimes be in quotes and sometimes not, implying that two kinds of fear were being discussed, but without explaining the different uses
• Several behavioral researchers who played an active role in this work did not view fear as a conscious feeling but instead as an empirically defined term based on observable events
• With the constraints of behaviorism loosened, animal consciousness is no longer a taboo topic
• Lacking the conceptual and historical foundations needed to navigate the ambiguous use of fear and the subtle issues that were being grappled with by those who treated fear as a nonsubjective intervening variable, readers today are easily drawn toward the conventional meaning of fear as a conscious feeling
• Avoidance conditioning became the main task used to explore brain mechanisms of fear and aversive learning in the 1950s, but this work led to inconclusive results
• By the 1980s, researchers turned to Pavlovian conditioning, which worked remarkably well, and Pavlovian fear conditioning became the "go-to" method in mammals for studying aversive learning
• The neural circuits and cellular, synaptic, and molecular mechanisms underlying the acquisition and expression of conditioned fear responses have been characterized in detail
• Fear conditioning is explainable solely in terms of associations created and stored via cellular, synaptic, and molecular plasticity mechanisms in amygdala circuits, without the need for conscious feelings of fear to intervene
• Research on patients with brain damage revealed that fear conditioning creates implicit (nonconscious) memories that are distinct from explicit/declarative (conscious) memory
• Behavioral studies in healthy humans have found that conditioned or unconditioned threats presented subliminally elicit physiological responses without the person being aware of the stimulus and without reporting any particular feeling
• If conditioned fear responses do not require consciousness in humans, we should not call upon conscious mental states to explain how a CS elicits freezing and autonomic conditioned responses in animals
• Conscious fear can occur when the conditions are favorable, but such conscious states come about through different processes that involve different circuits
• The function of the neural circuit that underlies fear conditioning is to coordinate brain and body resources to increase the chance of surviving the encounter predicted by the CS with minimal adverse consequences, not to make conscious fear
• As long as we use the term fear to refer to the neural mechanisms underlying both conscious feelings and nonconscious threat processing, confusion will occur
• Conscious fear can cause us to act in certain ways, but it is not the cause of the expression of defensive behaviors and physiological responses elicited by conditioned or unconditioned threats
• We should not have called it a fear system
• Careful analyses show that implicit processes often underlie, and in some cases account for, presumed mental states in animals
• Conscious mental states should not, in the absence of direct evidence, be the first choice explanation of behavior, even in humans
• When the processes in question are represented similarly in the brains of humans and animals, and do not require consciousness in humans, we should be especially cautious in giving conscious states a causal role in these processes and the responses they control in animals
• Loose talk by those "in the know" about the nonsubjective meaning of fear can lead to confusion when others encounter the term "fear"
• The story of fear research illustrates the perils of using an everyday term about human subjective experience, like fear, as a nonsubjective scientific term
• Loose talk by those who believe otherwise promotes misunderstanding
• It is not sufficient to simply say, "science is complicated, so those outside the field cannot be expected to know what is really going on"