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Mowrer’s Two Factor Model: Applications to Disaster Mental Health Services. Patrick O. Smith, Ph.D. Kim T. Suda, Ph.D. University of Mississippi Medical Center Abstract
Provides a review of Mowrer's Two-Factor theory and its application to acute intervention following trauma. The article identifies conditioned fear as variable rather than universal or automatic and suggests that acute post-traumatic interventions should remain flexible while assessing and addressing the different types and levels of problematic and adaptive reactions. Discusses an interesting application of a behavioral model for debriefing. Given an assessment and understanding of the contingencies surrounding an individual conditioned fear response, a debriefer using this model would be able to provide an individualized intervention to address problem areas.
Psychological debriefing is an intervention frequently utilized by emergency or mental health personnel when responding to disastrous events. Despite its extensive use, there has been little published attention to grounding this technique to theory. The present paper describes the application of Mowrer's two-factor learning model to event-related distress and discusses the development and use of debriefing interventions from a fear conditioning perspective. "Psychological debriefing" has penetrated most mental health communities in preparation for and response to disastrous events involving humans. A partial list of events receiving attention include personal violence, transportation accidents (viz., aircraft, motor vehicle, train, and shipping accidents), bombings, military actions, civil unrest, natural disasters (viz., tropical storms, hurricanes, tornadoes, earthquakes, mud slides, forest fires, and floods), hazardous material spills, and building collapses. Although specific vocational clusters exposed to disastrous events, such as law enforcement personnel, health care providers, and rescue workers, were originally targeted for psychological debriefing, its use has become increasingly widespread among civilian populations. The question of whether or not debriefing is an efficacious or necessary intervention in traumatic event situations has been a point of debate for several years (Bisson & Deahl, 1994; Ostrow, 1996; Raphael, Meldrum, & McFarlane, 1995). Currently, there are 213 publications representing "debriefing" in the PILOTS database. This literature base appears to follow the typical evolution of an immature domain in the science of human behavior as it mainly consists of case studies and anecdotal reports. However, there are a handful of empirical studies in this area and there has been a more recent shift toward research designs geared toward experimentation with heightened attention to scientific rigor. The base of knowledge being sought in these research endeavors has focused on the hypothesis that "psychological debriefing" may "cause" prevention of event-related distress and its potential psychological sequelea. However, as is often the case in an undeveloped research domain, there has been little published attention to grounding the technique, in this case, "psychological debriefing," to theory. This paper describes an application of a learning theory known as Mowrer's two-factor learning to event-related distress and comments on the development and use of debriefing interventions from a fear conditioning perspective. Although human event-related acute distress has been documented as early as 1870 for combat (U.S. Government Printing Office, 1870), active efforts to prevent event-related distress did not become common until the mid-1980's. Mitchell's early work (1983) describing a semistructured group intervention with emergency personnel (termed "Critical Incident Stress Debriefing or CISD") was vital for goading the behavioral science community into action to explore psychological debriefing. In general, psychological debriefing was designed to prevent or inhibit event-related distress by encouraging participants to recount their traumatic experience while focusing on related facts, thoughts, feelings, and reactions. Normalization of these thoughts and feelings are normalized to the extent possible and individuals are provided with information regarding possible future emotional reactions and appropriate mental health resources should they require them in the future (Dyregrov, 1989; Rose & Bisson, 1998). Not only has it been difficult to determine which of these components is critical in the debriefing process, but the efficacy of the debriefing process has been disputed. Rose and Bisson (1998) recently conducted a systematic literature review of brief early psychological interventions following traumatic events. Only six studies fulfilled inclusion criteria for well-controlled empirical research. More interestingly, only two studies revealed positive outcomes (Bunn & Clarke, 1979; Bordow & Porritt, 1979), while two studies resulted in negative outcomes (Bisson, Jenkins, Alexander, & Bannister, 1997; Hobbs & Adshead, 1996) and two revealed neutral outcomes (Lee, Slade, & Lygo, 1996; Hobbs & Adshead, 1996). Each of the studies conducted debriefing on an individual basis rather than in a group setting. Methodological discrepancies were noted in several of these studies, as well as variability regarding when the debriefing was offered and the exact procedure used. The authors concluded that these studies provided scant evidence that psychological debriefing could prevent psychopathology following a traumatic event. They also cautioned those currently using psychological debriefing due to the lack of scientific evidence of its utility and urged that additional research be conducted. Much of the research on debriefing may therefore be premature because there is not a scientifically sound theoretical understanding of event-related distress and debriefing. Although Everly (1993) provided a neurophysiological explanation for stress with applications to event-related distress, little empirical support exists to assist in understanding the impact of debriefing. A learning or conditioning conceptualization may advance the dearth of theoretical approaches to event-related distress and debriefing as was done by Keane, Zimering, and Caddell (1985) in posttraumatic stress disorder (PTSD) and exposure-based treatment. This treatment has since been acknowledged as an empirically supported intervention. Similarly, applying Mowrer’s theory to the debriefing process may help explain why it appears to be helpful for some people and not others. Mowrer (1947) was particularly interested in a learning interpretation of emotional reactions similar to the phenomenon known as "event-related distress." In his original theory, he developed a distinction between classical and instrumental conditioning by considering two forms of learning: sign learning and solution learning. More importantly, he formulated a two- stage relationship between these two forms of learning. Sign learning represented what is referred to as classical conditioning or the conditioning of respondent behavior and solution learning represented instrumental conditioning or learning of operant behavior. Consider an example in which a man is hit by an automobile. The pain from hitting the car is an unconditioned stimulus (UCS) which produces emotional responses characteristic of fear representing an unconditioned response (UCR). External sensory stimuli associated with the UCS including vision (e.g., sight of the car), audition (e.g., squealing of tires), olfaction (e.g., burned rubber), and gustation (e.g., blood in mouth) may become the conditioned stimuli (CS) for fear as a conditioned response (CR). Thus, straightforward classical conditioning or sign learning has taken place. When exposed to external sensory stimuli (CSs) in the future, fear (CR) is inappropriately experienced. The man learns that avoiding or escaping from these CSs reduces fear (CR), thus this behavior is reinforced. Operant conditioning or solution learning takes place with the avoidance or escape sequence. Mowrer (1960) reformulated this theory by focusing on the similarities of sign and solution learning. In the above example, the accident victim produces sensations (e.g., danger signs) via behavior that has become CSs for fear. Mowrer applied this same thinking to solution learning. In essence, he suggested that danger signs from the accident victim's behavior could lead to escape or avoidance behavior and result in fear reduction suggesting that internal sensations, thoughts and/or emotions could be conditioned. This modification introduced a more cognitive sounding solution to the connectionist approach to classical and operant conditioning by Mowrer. In addition, Skinner's radical behavioral acknowledgement of "private events" was recognized as potentially conditionable stimuli in Mowrer's final two-factor learning theory (1953). Presently, the use of CISD (Mitchell, 1983) and similar psychological debriefing techniques have been suggested as methods for the prevention of PTSD and for "mitigating the harmful effects of work-related trauma" (Mitchell & Everly, 1997). Implicitly, many debriefing proponents suggest that all persons exposed to the aforementioned type of events or occupations should routinely undergo psychological debriefing. If one were to accept Mowrer's conceptualization, one would presume that all humans exposed to these events or occupations experience conditioned fear. However, this is not always the case. Rachman (1977) addressed the inherent difficulty in making this assumption in his cogent review of fear conditioning theory. He summarized several conclusions regarding fear acquisition which appear to be particularly relevant when applying Mowrer’s two-factor model to event-related distress and psychological debriefing. Rachman’s conclusions also help identify the strengths and weaknesses of applying the two-factor model to the debriefing process. Briefly, Rachman reasoned that 1) even though fear conditioning takes place in humans and animals, neither always acquires fear in situations that "should" lead to fear conditioning; 2) stimuli equipotentiality does not exist in fear conditioning; 3) human fear is variable and difficult to predict; and 4) partial evidence supports the existence of vicarious transmission of fear. The application of his fear conditioning review to the psychological debriefing process draws into question the wisdom of blanket prescriptions of these techniques and may help to explain its potentially harmful effects (Bisson, Jenkins, Alexander, & Bannister, 1997). An expanded application of Rachman’s conclusions to event-related distress and psychological debriefing follows. Fear conditioning can and does take place in humans and animals. However, neither group always acquires fear in situations that should lead to fear conditioning. Rachman (1977) exemplified this by noting that the majority of people exposed to WWII air raids managed extraordinarily well, in spite of experiencing acute intense reactions. These reactions typically dissipated spontaneously. In a more recent example, Kulka et al. (1990) reported that 15% of Vietnam veterans experienced PTSD or other psychological problems at the time of their study. Conversely, this suggested that 85% of these veterans were relatively problem-free. Thus, the majority of people exposed to traumatic events may not need crisis intervention or psychological debriefing. For example, each person surviving a train accident or airplane crash will not be affected in the same manner. Therefore the appropriateness of utilizing psychological debriefing in every case is questionable. In fact, Koopman, Classen, and Spiegel (1994) cautioned against indiscriminate prescriptions of psychological debriefing because assessment of certain factors, including subjective levels of arousal, current coping processes, cognitive impairments, or past exposure to previous trauma, are not often assessed prior to providing these interventions. The absence of assessment and the failure to address these factors may be one of the reasons why debriefing has not systematically yielded positive results for those involved in a traumatic event (Koopman, Classen & Spiegel, 1994). Research studies that assess these pertinent individual or group factors are needed. Multimodal measures assessing behavioral, cognitive, emotional, and physiological changes in individuals following a traumatic event could be extremely beneficial during the initial assessment process. For example, utilizing portable psychophysiological monitoring apparatus (e.g., ambulatory blood pressure or heart rate monitors) (Muraoka, Carlson, & Chemtob, 1998), obtaining collateral reports, or collecting self-report information (possibly using palmtop computers) may provide more proximal measures of intense or negative responses to CSs associated with disastrous events. These measures would assist in guiding the appropriate level of intervention. Rachman (1977) also addressed the issue of stimuli equipotentiality in relation to fear conditioning. While fear conditioning theory assumes that all stimuli have roughly an equal chance of being transformed into fear signals or conditioned stimuli, in reality, this is not the case. Seligman’s (1971) preparedness theory hypothesized that some fears are acquired more rapidly than others, generalize broadly to other stimuli, and are more resistant to extinction. Seligman stated that the body’s preparedness to fear certain events has biological significance in that the majority of phobias concern objects of natural importance (e.g., snakes, spiders, dangerous weather, etc.) which may be related to survival of the fittest. When individuals are exposed to an event that may be considered traumatic, certain stimuli may later trigger negative responses more so than others and therefore be more resistant to extinction. Future research investigating which CSs following event-related distress are especially extinction-resistant may assist in providing important information for the debriefing process. For example, are triggers such as stormy weather conditions or dangerous animals more likely to serve as cues for panic or fear as compared to more innocuous stimuli seen or heard during a traumatic situation? Another of Rachman’s positions asserts that the distribution of human fear is variable and is extremely difficult to predict. As mentioned, not every person will react to a traumatic event in the same manner or with extremely intense emotional, behavioral, or physiological responses. Individual response modes and a variety of mediating factors need to be taken into consideration. In addition, Rachman (1977) suggested that some fears may be more innate or culturally influenced. Future research addressing the distribution of human fears when exposed to disastrous events would be beneficial in identifying any cultural differences. This could also be a significant factor in improving the application and long-term efficacy of debriefing for specific populations. Finally, Rachman (1977) supported the idea that fear could be acquired directly or vicariously. Bandura (1969, 1971) initially reported that behavioral and emotional responses could occur through vicarious learning situations via observational learning or modeling. Rachman further proposed that fears could be learned in a similar manner when stimuli was associated with fear directly or vicariously. He questioned whether or not fear reactions could be acquired to stimuli in which a person has never encountered personally. This question remains relevant today. An early source of support for this indirect phenomenon of fear conditioning was provided when children were shown to exhibit more fear behavior during WWII air raids if their mothers displayed intense fear. Today, vicarious learning could, in part, account for those individuals who suffer from event-related distress without direct exposure to the event. The notion is that "hearing" about the event could lead to a "learned" CR. However, as mentioned earlier the majority of emergency response/mental health professionals do manage their jobs without seeking professional assistance (Ostrow, 1996). When is the most appropriate time to offer assistance, if any, and to whom? How does one differentiate "normal" reactive responses that are part of basic coping mechanisms versus psychopathic responses that should be treated? These are basic questions that have yet to be adequately answered in the literature. Clearly, there are several areas that continue to require empirical validation in the area of psychological debriefing. Since its inception, there have been few controlled studies regarding the efficacy of these techniques. Case studies, anecdotal reports, and the occasional randomized study have resulted in varied positive, negative, or neutral findings (Rose and Bisson, 1998). The current paper applied Mowrer’s two-factor learning model to event-related distress in an effort to highlight the importance of developing debriefing techniques from a theoretical stance. The complexity of fear acquisition was also discussed noting that fear does not always occur in situations that "should" lead to such conditioning, stimuli equipotentiality does not exist in this area, fear is variable and difficult to predict, and vicarious transmission of fear appears to occur (Rachman, 1977). Given these conclusions and the inherent difficulties associated with conducting research in the area of event-related distress, one can understand why this remains a relatively undeveloped field of study. However, among mental health providers, most believe that it is inappropriate to treat any condition until one has conducted a careful assessment of the problem. In the area of psychological debriefing, this has yet to be done on a consistent basis. Only with accurate and complete assessments before and after the application of debriefing procedures can we truly know who is affected, how, and for what length of time. Tailoring the debriefing process to the individual may be the critical element to a successful outcome. Presently the influence of debriefing is unpredictable and remains controversial. Establishing an understanding of debriefing and fear conditioning mechanisms will provide a pathway to the development of empirically supported uses of psychological debriefing. According to Agras (1997), understanding the factors related to successful interventions is derived by dismantling studies that utilize procedures believed to be central to therapeutic change. Once the literature is able to clarify whether or not debriefing, in general, is a beneficial technique to use (or can target specific populations, events, or time-periods), further research will need to address which are the most effective components. 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