Preparedness Theory Essay, Research Paper
How has preparedness theory attempted to integrate a Pavlovian model of the acquisition of specific phobias with this biological specificity? What is the status of Preparedness theory today?
When confronted with a phobic object or situation an individual appears to have little control and no alternative but to avoid the feared object or situation (Ohman & Soares, 1993). Consequently, individuals with a phobia can be vulnerable to anxiety induced automatic reactions to an object or situation which in turn can place major restrictions on everyday life (Ohman & Soares, 1993). Phobias are characterised as a conditioned reaction that is specific, persistent, intense and irrational with a compelling need to avoid the phobic object or situation (Reber, 1995). The majority of phobias concentrate on a small number of fear inducing stimuli such as snakes, spiders, heights, thunder and confined spaces. These biological stimuli are more likely to develop into a phobia than non-biological stimuli such as firearms, broken glass and motor cars, even though humans are more likely to have an aversive experience with non-biological stimuli. Preparedness theory was introduced by Seligman (1971) whereby the concept of preparedness attempts to explain why fears and phobias are so much more likely to occur with biological stimuli than non-biological stimuli (Davey, 1995). I will discuss classical conditioning and preparedness theory and how preparedness theory has attempted to integrate a Pavlovian model of the acquisition of specific phobias with this biological specificity. Further, a contemporary status of preparedness theory is discussed by means of an evaluation of available evidence.
Russian psychologist Ivan Pavlov established the study of classical conditioning (Bourne & Russo, 1998). Kalat (1998) states that classical conditioning involves a modification of involuntary behaviour. In this process, a neutral stimulus that causes no natural response in an organism is associated with an unconditioned stimulus (US), an event that automatically or naturally causes a response (Bourne & Russo, 1998). This association causes the response to the US, the unconditioned response (UR), to transfer to the neutral stimulus (Bourne & Russo, 1998). The US no longer needs to be there for the response to occur in the presence of the former neutral stimulus. Given that this response is not natural and has to be learned, the response is now a conditioned response (CR) and the neutral stimulus is now a conditioned stimulus (CS) (Bourne & Russo, 1998). In Pavlov’s experiment a tone was the neutral stimulus that was associated with the US of food. The UR of salivation became a CR to the newly CS of the tone (Schwartz & Robbins, 1995). The function of the Pavlovian model of classical conditioning is primarily to assist an organism in preparing for some forthcoming important event (Kalat, 1998). Classical conditioning when applied to phobias, postulate that the response of phobic fear is a reflex acquired to non-dangerous stimuli. For example the normal fear to a dangerous stimulus, such as a poisonous snake, has been over generalised to non-poisonous snakes as well. However Ohman & Soares (1993) maintain classical conditioning does not account for the disassociation between cognitions and conditioned behaviour.
According to Marks (1989) most dangers that humans are likely come across have already been encountered by our ancestors. In the past, those who responded to danger lived longer and had more descendants. Marks (1989) describe prepotency as a physiological system that makes an organism respond attentively to certain cues. Further, organisms are predisposed to learn certain reactions to particular stimulus, such as fear rather than nausea is the reaction to snakes and heights where as rotting food would elicit a nauseous response instead of fear. Marks (1989) maintains this is preparedness and prepotent attention to particular stimulus is the first step toward prepared reactions. As indicated by Marks (1989) prepared learning of fear is somewhat mediated by the reactions of peers. Studies of observational learning of fear of snakes in rhesus monkeys indicate that monkeys who are not initially afraid of snakes will rapidly acquire an intense fear when they have watched conspecifics exhibiting such fear (Mineka 1894, cited in Marks, 1989). Furthermore, monkeys fail to acquire fear toward leaves or flowers using the same paradigm, such that prepotency and preparedness lead to a non-random distribution of fears.
According to Seligman (1970, cited in McNally, 1987) human beings and certain animals have a biological preparedness for certain occurrences and forms of conditioning. Further, the notion of preparedness applies to associations not to stimuli or responses and it is assumed that people need a learning episode for a fear to develop. On a continuum, some organisms become strongly conditioned on a single trial and others become conditioned weakly or not at all as viewed by Seligman (1970, cited in McNally, 1987). Seligman (1971; Davey, 1995) claim that organisms can be prepared – a tendency to learn an association quickly; non-prepared – middle of the continuum where learned associations are acquired neither quickly nor slowly; or contra-prepared – opposite limit, where an organism learns an association only with great difficulty.
According to Seligman (1971) there are four characteristics that distinguish phobias from fears conditioned in the laboratory; ease of acquisition, irrationality, belongingness and high resistance to extinction and added that phobias are probably non-cognitive. Seligman (1971) maintains these differences can be explained by preparedness theory. Further, fears established in the laboratory have limited evolutionary significance. Fears such as fears of specific animals and fear of heights are fairly common phobias and Seligman (1971) maintains that it is rare that we have phobias of pyjamas, grass or electric-outlets even though these things are more likely to be associated with trauma.
To provide evidence of his theory, Seligman draws on a study conducted by Garcia & Koelling (1966, cited in Bourne & Russo, 1998 & McNally, 1987), on water-deprived rats. Rats were fed sweetened tasting water while a bright light flashed and a noise sounded. At the same time, rats in one group received electric shock to the feet and the rats in the other group were treated with X-ray radiation to cause nausea and illness. When the rats became ill a few hours later, they acquired an aversion to sweet tasting water but not to light or noise. According to Seligman (1970, cited in McNally, 1987), evolution had prepared the rats to associate taste with illness, but had contra-prepared the association between noise/light and illness. These outcomes confirmed the view that the associations in classical conditioning are not arbitrary and some connections are more readily formed than others (Bourne & Russo, 1998). In a classical conditioning paradigm, organisms may be prepared to form certain CS-US associations and contra-prepared to develop others. When the rats learn taste aversion to food causing illness the association is easily formed, but when the taste aversion to food is paired with foot shock it is difficult to form (Bourne & Russo, 1998). Ohman & Soares (1993) claim that in Seligman s model (1971) when applied to phobias represent CR s and suggest that organisms have been formed by evolution to readily associate anxiety and aversion with potentially deadly situations.
According to Ohman and coworkers (1984, cited in Marks 1989) when preparedness theory is applied to phobias it gives a possible explanation. Preparedness theory has been tested by Ohman et al in circumstances where the subject’s experience of prepared stimuli has been strictly controlled (Marks, 1989). In this experiment slides of snakes and spiders are presented as fear relevant (FR) CS and paired them with electric shock as the US. Conditioning to these FR stimuli was then compared with conditioning to fear irrelevant (FI) stimuli such as slides of houses, flowers, and mushrooms. McNally (1987) carried out a comprehensive review of these laboratory studies in an attempt to corroborate research in support of preparedness theory, scrutinising ease of acquisition, irrationality, belongingness and resistance to extinction. McNally (1987) found no convincing evidence for the four characteristics that distinguish phobias from fears conditioned in the laboratory. McNally (1987) concluded that as preparedness theory of phobias was designed to explain dissimilarities between the traditional learning model, all assumptions except evolutionary significance are questionable.
Lovibond, Siddle & Bond (1993) provide experimental data that reveals the uncertain effectiveness of biologically prepared stimuli for human fear conditioning. The results of their study support their hypothesis that such stimuli owe their effectiveness not to associative processes but to selective sensitisation. Lovibond et al (1993) report on experiments by Ohman, Eriksson, Fredriksson, Hugdahl & Olofsson (1974, cited in Lovibond et al, 1993) that prior to conditioning taking place, FR stimuli elicited larger electrodermal responses than FI stimuli. Further, the threat of electric shock noticeably enhanced the difference. Lovibond et al (1993) refer to the increase in electrodermal responding to all stimuli after shock threat, as sensitisation and selective sensitisation is defined as the differential increase in responding to FR stimuli. Lovibond et al (1993) maintain that selective sensitisation may account for previous reports of resistance to extinction of FR conditioning that have been taken to support preparedness theory (Seligman, 1971 citing in Lovibond et al, 1993).
Davey (1995) proposes that the non-random distribution of fears is not as clearly related to biological preparedness but to biases in the information processing of threatening stimuli. Davey (1995) claims the traditional Pavlovian model of conditioning states selective associations are measured in terms of the strength and persistence of CR s, recently however processing of FR stimuli and aversive consequences have been the focus of attention. Differences in the strength and persistence of conditioned fear responses appear to account for cognitive biases. According to Davey (1995) expectancy bias allows rapid learning concerning any stimulus that the individual has reason to believe is dangerous.
To summarise, preparedness theory integrates the Pavlovian model of classical conditioning primarily by assisting an organism in preparing for some forthcoming important event. Preparedness theory is based on an evolutionary point of view and further Marks (1989) claims prepotency and preparedness lead to a non-random distribution of fears. Stimuli such as snakes, heights, storms, blood and strangers are predominantly ancient threats and exaggerations of natural fears (Marks, 1989). In this essay, classical conditioning, preparedness theory and evidence of significance to preparedness theory has been discussed. In addition alternative explanations to preparedness theory have been briefly discussed to expound on where preparedness theory is today. Available evidence suggests preparedness theory accounts for the uneven distribution of fears however there has recently been debate that selective sensitisation and expectancy biases may also co-exist with preparedness theory.
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