آیا یک چارچوب موثر برای درک توسعه و درمان هراس مفید است؟

Despite the prevalence of therapeutic interventions based on conditioning models of fear acquisition, conditioning has been seen by many as a poor explanation of how fears develop: partly because research on conditioning has become less mainstream and models of learning have become increasingly more complex. This article reviews some of what is now known about conditioning/associative learning and describes how these findings account for some early criticisms of conditioning models of fear acquisition. It also describes how pathways to fear such as vicarious learning and fear information can be conceptualised as forms of associative learning that obey the same learning rules. Some popular models of conditioning are then described with a view to highlighting the important components in learning. Finally, suggestions are made about how what we know about conditioning can be applied to improve therapeutic interventions and prevention programs for child anxiety. Conditioning as an explanation of phobic responding arose from Watson and Rayner's (1920) famous demonstration that aversive and avoidant responses towards a previously neutral stimulus could be learned. In their study, a 9-month-old child, Albert B, was pre-tested to see whether he was initially fearful of various stimuli (including a white rat and the noise made by banging a claw hammer on an iron bar). Having established that Albert was not fearful of the rat but was scared by the noise, Albert was placed in a room with the rat and every time he touched the rat, or the rat approached him, Watson hit the iron bar, thus scaring the child. After several pairings of the rat with the loud noise, Albert began to show signs of anxiety when the rat was presented without the loud noise. Although Watson himself did not formulate a coherent theory of phobia acquisition, the implication from the study was that excessive and persistent fear (i.e. a phobia) could be acquired through experiencing a stimulus in temporal proximity to some fear-inducing or traumatic event. In conditioning terminology, this stereotyped and oversimplified account would suggest that the rat was a conditioned stimulus (CS) and the loud noise an unconditioned stimulus (US), which is a stimulus that evokes a natural response called the unconditioned response (UR): in this case anxiety. Through pairing of the CS and US, and the formation of a CS–US association in memory, the CS comes to evoke a response called the conditioned response, CR (see Fig. 1). Clinically speaking, conditioning at the time had two important characteristics: Equipotentiality and Extinction. Equipotentiality refers to the observation that any predictor should be able to enter into an association with any outcome; the implication is that a phobia of anything can develop provided that it is at some point experienced alongside trauma. Extinction refers to the well-demonstrated effect that if a predictor (CS) is presented alone (i.e. without the outcome) after a response has been acquired, then the strength of that response will decline over successive trials until the predictor stimulus no longer elicits a CR. The implication of extinction for clinical psychology was that exposure to the CS (the target of the phobia) without the trauma would allow the anxious response to extinguish. This simple idea formed the basis of behaviour therapy (see Wolpe, 1961) which even to this day is successful in treating specific phobias ( Öst, Svensson, Hellstrom, & Lindwall, 2001). Full-size image (18 K)

This paper has reviewed some of what is now known about phenomena and theories of conditioning (or associative learning) and has argued that it is a fruitful way to conceptualise how fears might develop. Not only do a broad range of learning phenomena conform to similar principles (human causal learning seems to obey similar rules to ‘basic’ conditioning in animals), but the various models of associative learning allow firm predictions about when and how fears might develop in children. By using conditioning as a framework for understanding direct fear acquisition, vicarious learning and fear information we stand some chance of gaining better insight into how to prevent and treat phobias.