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Clinicians' and laypeople's beliefs about the causal basis and treatment of mental disorders

Dissertation
Author: Caroline Courtney Tuzo Proctor
Abstract:
Mental disorders are a major public health concern, and knowing how people think about their causes and treatments can help ensure the success of public education efforts. In the current studies, I examine beliefs about the biological and psychological causes of mental disorders and how they relate to beliefs about the effectiveness of medication and therapy at treating different disorders. In Study 1, I found a systematic preference for within-domain cures among undergraduates: the more a mental disorder is regarded as biologically caused, the more effective medication is thought to be at treating it, with the opposing trend for psychotherapy. The opposite pattern of treatment preferences was found for disorders thought be psychologically caused. In Study 2, I examined beliefs about how treatments affect the mind and brain, and find that undergraduates and adults believe therapy actually has more effect on the mind than the brain, and medication has more effect on the brain than the mind. This systematic pattern suggests that people might be swayed by dualist forms of reasoning, in which they think of biological and psychological phenomena as largely separate and causally distinct domains. Consistent with this idea, in Study 3, I found that people are willing to agree that the symptoms of more psychologically-caused disorders are less a reflection of brain-functioning than more biologically-caused disorders. In Study 4, I examined clinicians' causal beliefs about disorders and found that though they acknowledge all disorders are caused by both biological and psychological factors, the relative importance of each type of cause varies across disorders. Finally, in Study 5, I found that similar to undergraduates, clinicians believe that cases of a mental disorder caused by biological factors are thought more treatable by medication than cases of the same disorder caused by psychological causes. I discuss whether such beliefs about treatment are normative, their possible impact on adherence to prescribed treatments, and the implications of causal beliefs for attitudes, blame, and sympathy for those suffering from mental disorders.

Table of Contents List of Figures and Tables vi Acknowledgements viii Introduction 1 Study 1: Undergraduates' Beliefs About the Causes and Cures of Mental Disorders 14 Study 2: Beliefs About How Treatments Affect the Mind and Brain 26 Study 3: Beliefs About the Brain's Involvement in Mental Disorders 43 Study 4: Clinicians' Beliefs About the Causes of Mental Disorders 58 Study 5: Clinicians' Beliefs About the Treatment of Mental Disorders 74 General Discussion 88 References 102 Appendix A: Additional Materials for Study 1 116 Appendix B: Additional Materials for Study 2 122 Appendix C: Additional Materials for Study 4 124 Appendix D: Additional Materials for Study 5 131 v

List of Figures and Tables Figure 1. Mean ratings of the extent to which undergraduates regard mental Disorders to be biologically- and psychologically-caused and treatable by medication and therapy 20 Figure 2: Treatment effectiveness for the most biological and psychological disorders 22 Figure 3. Undergraduates' and adults' beliefs about the effect of treatments on mental and physical phenomena 35 Figure 4. Endorsement of mind-brain stances by participants in Study 2 36 Figure 5. Beliefs in the effects of medication and therapy by education in Study 2 39 Figure 6. Beliefs that the biological and psychological mental disorders symptoms reflect brain functioning in Study 3 49 Figure 7. Beliefs and attitudes towards those with more biological vs. psychological mental disorders 52 Figure 8. Distribution of the domains of mental disorder causes 66 Figure 9. Average importance index of biological, psychological, and environmental causes for disorders in Study 4 68 Figure 10 A, B, & C . The 18 coding categories of causes graphed by their average biological and psychological ratings (A), average environmental and psychological ratings (B), and average environmental and biological ratings (C) 70 Figure 11. Clinicians' overall beliefs about the effectiveness of medication and therapy for treating nine mental disorders 81 Figure 12. Mean beliefs about treatments for cases of GAD, MDD, and alcohol abuse caused by biological and psychological/environmental causes 85 Table 1. Summary of stepwise regression analyses for variables predicting brain's involvement in mental disorders 50 Table 2. Percentage of causes from psychological, biological, and/or environmental domains listed for each disorder 65 Table 3. Sample materials asking clinicians to rate the effectiveness of psychotherapy from Study 5 77 Table 4. Correlations between the importance indices of biological, psychological, and environmental causes (Study 4) and beliefs about mean treatment effectiveness (Study 5) 82 vi

Table 5. Mean medication and therapy effectiveness ratings for cases of MDD, GAD, and alcohol abuse caused by biological and psychological /environmental causes 86 Appendix B Figure 1. Item differences in Study 2 123 Appendix C Table 1. The average number of causes listed for each disorder in Study 4 124 Table 2. Average percentage of causes from the four most common cause types, broken down by expert group 125 Table 3. Correlations between domain ratings of causes within each disorder 128 Table 4. Examples of listed causes from each coding category and a breakdown of their relative prevalence for different disorders 129 Table 5: Popularity of cause coding categories by expert type 130 Appendix D Table 1. Correlations (by subject) between beliefs about the biologically, psychological, and environmental cause ratings for disorders (Study 4) and beliefs about treatment effectiveness (Study 5) 132 Table 2. Correlations between the importance indices of biological, psychological, and environmental causes (Study 4) and beliefs about mean treatment effectiveness (Study 5) across all disorders (i.e. including mental retardation) 133 Figure 1. Beliefs about the effectiveness of treatment for biologically- vs. psychosocially-caused cases of the 6 mental disorders not presented in the main text 134 vii

Acknowledgements This work is very indebted to Woo-kyoung and Frank, for their intellectual encouragement and the way they challenged me to think critically and improve my work. I have also learned so much from my fellow graduate students, most especially Jessecae, Christian, and Ben. Finally, special thanks goes to Nick, who was a source of incredible support throughout my entire graduate years. vni

Beliefs About Mental Disorders Clinicians' and Laypeople's Beliefs About the Causal Basis and Treatment of Mental Disorders Mental disorders are a major public health concern. Current statistics indicate that about 26% percent of American adults are affected by mental disorders during a given year (Kessler, Chiu, Demler, & Walters, 2005), and this costs at least $193 billion annually in lost earnings alone (Kessler et al., in press). Certainly studies of the prevalence, origin, expression, and treatment of mental disorders are crucial to solving this mental health crisis, however work in cognitive psychology can also play a useful role in this arena. In particular, knowing how people think about the causes and treatments of mental disorder can help in education efforts, as the personal and economic losses due to mental disorders are exacerbated when people fail to recognize disorders or seek proper treatments. In the current experiments I will explore undergraduates', adults', and clinicians' beliefs about the causes and treatments of mental disorders. In five studies I will illustrate how people believe mental disorders vary in how biological and psychological they are, how they believe treatments vary in how they affect the mind and brain, and how this relates to differences in the perceived effectiveness of medication and therapy at treating different disorders. I will also explore whether these findings might reflect patterns of dualist thinking, in which biological and psychological realms are thought to be fundamentally separate levels of analysis. Such beliefs can have considerable impact not only on what treatments clinicians decide to give to their clients, but also to what degree clients adhere to medication regimens and/or have successful therapy outcomes. 1

Beliefs About Mental Disorders Folk Domains in Explaining Behavior Psychological research suggests that people use different levels of explanation to explain the world around them. Much work in cognitive development has shown that people have at least three different framework theories for reasoning about the world (see Wellman & Gelman, 1992 for a review). Each framework theory (also known as explanatory modes or domains) emphasizes different causes and causal principles. While folk physics emphasizes how physical bodies interact in terms of basic forces (e.g. gravity) and properties of objects (e.g. solidity), folk biology is used to understand living beings in terms of processes such as growth, reproduction, inheritance, illness, and death. Finally, folk psychology employs concepts such as beliefs, desires, and reasons to explain the voluntary behavior of agents. Certainly, there is evidence that adults and children are extremely flexible at using these different levels of explanation when it comes to understanding human behavior. It is not the case, for example, that people believe mechanical-physical explanations apply only to objects, biological explanations apply only to non-human animals, and psychological explanations only to people. Rather, experiments and analyses of natural speech samples show that by three years of age, children explain the behavior of people in terms of diverse modes (Hickling & Wellman, 2001). For example, children use psychological explanations to explain intentional acts and mistakes, biological explanations for why someone cannot hang from a tree forever, and physical explanations for why someone cannot float in the air (Schult & Wellman, 1997). From at least seven to eight years of age, children also seem to understand that both biological-level and psychological-level explanations can be applied simultaneously 2

Beliefs About Mental Disorders to the same behavior. In particular, children will agree that disordered behavior symptomatic of mental disorders can be caused by both biological and psychological factors. Although some disorders are seen as the result of largely social/psychological causes (e.g. depression; Charman & Chandiramani, 1995), and other disorders as largely due to biological causes (e.g. dementia, social withdrawal; Fox, Buchanan-Barrow, & Barrett, 2007; Maas, Maracek, & Travers, 1978), children do list both biological and social-environmental causes for other disorders (e.g. ADHD, self-punitive behavior, anxiety; Maas et al., 1978; Smith & Williams, 2004). Moreover, the tendency to acknowledge both types of causes as equally plausible or as combining to produce symptoms seems to increase with age (McMenamy, Perrin, & Wiser, 2005). Adults certainly appeal to both biological and psychological causes of mental disorders. National surveys indicate that although different countries, cultures, and ethnic and racial groups differ in the relative emphasis they place on different types of causes, most endorse both biological explanations (such as genetics, injury, or brain physiology) and psychological environmental explanations (such as day-to-day problems and traumatic events) (Dietrich et al., 2004; Furnham & Chan, 2004; Jorm, 2000; Link, Phelan, Bresnahan, Stueve, & Pescosolido, 1999; Nakane et al., 2006; Narikiyo & Kameoka, 1992; Schnittker, Freese, & Powell 2000). Even those in non-Western countries, who are more likely to invoke supernatural explanations of disorders, also endorse both biological and psychological causes of illness as well (Jorm, 2000; Mulatu, 1999; Patel, 1995). Lack of Belief in Cross-Domain Effects 3

Beliefs About Mental Disorders However, although people acknowledge that biological and psychological causes impact human behavior, there is some evidence to suggest that can people have difficulty appreciating that certain biological and psychological phenomena can affect each other. Thus although even young children believe that their willful intentions to act are responsible for their physical actions (Nichols, 2004), there is some evidence that children do not think that other mental phenomena can affect the body. For example, children from kindergarten through fifth grade deny that psychogenic illnesses are possible. While they believe that psychological events (feeling nervous) can cause behavioral outcomes (jiggling legs), they do not think psychological events (e.g. feeling worried) can cause physical health outcomes (getting a tummy ache) (Notaro, Gelman, & Zimmerman, 2001). Even when using unfamiliar stimuli about 'aliens' with which they have no prior experience, or when the amount of supporting evidence is carefully controlled, preschoolers are still less likely to choose a "cross-domain" (i.e. psychological) cause of a biological illness than a "within-domain" (i.e. biological) cause (Notaro et al., 2001; Schulz, Bonawitz, & Griffiths, 2007). This tendency to believe some biological and psychological phenomena do not interact seems to continue even to adulthood. Lynch and Medin (2006) solicited causal models of depression from nurses, undergraduates, and energy healers and found that while nurses and undergraduates included both types of causes, they put psychosocial and physical causes on separate causal chains. On average, students cited cross-domain relations in which a biological factor impacted a psychological one, or vice versa, only 10% of the time, nurses only 25%. Only those trained in a form of alternative medicine 4

Beliefs About Mental Disorders (energy healers) were willing to put different domains on the same causal chain and cited cross-domain relations about 40% of the time. Finally, people also seem to have difficulty understanding how interventions associated with one explanatory domain can affect another. For example, although adults generally admit that psychogenic illnesses are possible (Inagaki & Hatano, 1999; Notaro, Gelman, & Zimmerman, 2002), they do not generally endorse biological cures for these psychologically-caused problems. In one study, adults thought a flu-induced headache was treatable by medicine but a stress-induced headache was not. A follow-up questionnaire that emphasized the biological symptoms of such psychogenic illnesses still found that only 38% of adults endorsed a biological cure for what they seemed to regard as 'psychological' problems (Notaro et al., 2002). Within-Domain Treatment Preferences for Mental Disorders Beliefs that such 'cross-domain' treatments are less effective could have a big impact in the mental health arena where treatments associated with both the biological domain (medication) and the psychological domain (psychotherapy) are regularly used. If the general public does not believe medication can affect their psychological problems, they may be less likely to adhere to a psychiatrist's prescribed regimen. Others might think that psychotherapy could never improve what they regard as their biological symptoms, and therefore never seek this kind of help. If clinicians also hold beliefs that cross-domain treatments are less effective, this could have considerable impact on what treatment plans they pursue, and ultimately their success in helping clients. The current studies are therefore designed to examine to what extent laypeople and clinicians think 5

Beliefs About Mental Disorders within- and cross-domain cures vary in effectiveness, and explore some possible explanations for their beliefs. Indeed there is some preliminary evidence that laypeople differentiate mental disorder treatments as to whether they are psychological (therapy) or biological (drugs, exercise, diet) and believe that psychological cures are not appropriate for disorders perceived to have biomedical causes and vice versa (Furnham, 1995; Furnham & Buck, 2003; Goldstein & Roselli, 2003; Iselin & Addis, 2003; Luk & Bond, 1992; Mulatu, 1999; Narikiyo & Kameoka, 1992). However, previous work in this area has used within- subjects designs that may have created experimental demand for subjects to match causes and cures. To address this issue, in my first experiment (Study 1)1 use a between- subjects design to examine if beliefs in the effectiveness of within-domain cures are truly robust and not experimentally induced. However, assuming that people do this, why do they do it? One possibility is that judgments about cross-domain phenomena are due to pre-existing beliefs about what tends to be true in the world. People might know in theory that biological phenomena can affect psychological phenomena (and vice versa), but, through their own experiences have come to believe therapy does not actually help schizophrenia, or that feeling worried does not usually cause a tummy ache. Another possibility is that people's beliefs about how psychological and biological phenomena relate reflect their deeper underlying metaphysical views about the brain and mind. With this possibility in mind, I next summarize some philosophical accounts of how psychological states related to the biological brain that laypeople might possibly endorse. 6

Beliefs About Mental Disorders Philosophical Accounts of How the Mental Experiences Relate to the Brain Descartes (1641/1984) was the philosopher who started modern discussion of what is known as the mind-body problem. His position, known as substance dualism, postulated that the mind and brain were made of entirely different substances. While the brain was made of matter, whose defining characteristic was that it was extended in space, the mind was made of an immaterial substance, whose defining characteristic was that it thinks. Thus psychological phenomena (thought, feelings, emotions) were in a realm separate and independent from the physical brain. According to this view, something can affect the mind and psychological states, without there being any change to the brain. Similarly changes to your brain might produce no change to mental states. However, in light of overwhelming evidence that mental experiences are linked to brain structure and function, substance dualism has been summarily rejected by scientists and philosophers as a legitimate view of the mind (but see Popper & Eccles, 1977). Most credible views of the mind advocate materialism, in which the physical brain is the only substance responsible for psychological states. Philosophers have delineated different forms of materialism that people might believe in. Type identity theory argues that mental states are equivalent to brain states. Just as water is identical with H2O, type identity theorists argue that a feeling of happiness is identical to the activation of a specific group of neurons (Feigl, 1958; Place, 1956; Smart, 1959). Under this view, if something affects a mental state, there must be an equivalent change in brain state as well, as they are one and the same thing. 7

Beliefs About Mental Disorders Other materialist theories (e.g. one of the most currently popular views of the mind, functionalism1) make a looser claim that mental states aren't identical to brain states but they supervene on physical states - meaning that mental states are dependent on and determined by lower-level physical properties (Davidson, 1970; Kim, 1993; Lewis, 1986)2. If mental states supervene on physical states, there cannot be a change in a mental state without there also being a change in a physical state. However, because there is no one-to-one relationship between the mental and physical, it is possible that small changes in the brain might correspond to large changes in mental states, or large- scale changes in the brain might have little or no impact on mental states. However, it is also possible that people can hold one of these materialist understandings of the mind but still maintain other forms of dualist thinking that are interesting and pervasive. In particular, from the evidence reviewed above, it seems clear that, at the very least, people are 'explanatory dualists' - they regard biological and psychological phenomena as fundamentally distinct and appeal to both domains when explaining human behavior. Functionalism argues that mental states are defined in terms of their causal interactions with each other and with sensory inputs and behavioral outputs (Dennett, 1978; Fodor, 1981; Putnam, 1960, Pylyshyn, 1984). Thus "feeling happy" might be defined as a state that is a result of hearing a funny joke, and that causes you to smile, approach people, and laugh. Practically speaking, however, every functionalist theory argues that human mental states are instantiated in the physical brain. 2 Because supervenience specifically argues that mental and physical changes are related in a specific law-like way, it actually can technically be considered consistent with many metaphysical views, including substance dualism. For example, it could that the mental substance is completely different than the physical substance but that they just happen to travel in step together, such that supervenience still holds. However, the power and appeal of dualist theories lies in their denial of such coincidental 'parallelism' (but see Leibniz, 1765/1996) and so we consider endorsement of supervenience to be an endorsement of materialism. 8

Beliefs About Mental Disorders Moreover, philosophical analyses suggest that explanatory dualism is a valid and epistemologically useful strategy (Dennett, 1995; Putnam, 1975). Although psychology may be ultimately dependent on biology, many argue that each domain has its own legitimate research tradition and methods and can make separate explanatory contributions to a phenomenon (Engel, 1977; 1980, McCauley, 1996; Fodor, 1987, Maxwell, 2000, but see Churchland, 1986 for a different perspective known as eliminative materialism). For example, we can learn useful things about the medical disorder asthma by studying it at the cellular level (allergens trigger TH2 cells to activate the humoral immune system), organ level (airways constrict and release mucus), psychological level (asthma attacks are often triggered by emotional stress), and societal level (incidence of asthma is highest among low-income populations), among others. Similarly, we can learn useful things about human behavior by employing both psychological and biological explanations. Dualism as a Possible Explanation for Treatment Preferences Do laypeople's beliefs about biology and psychology match up with any of these philosophical accounts of the brain (forms of dualism, type identity theory, supervenience)? Certainly, it seems likely that most educated adults would not endorse substance dualism, but the findings discussed above - in which people do not always think mental and physical phenomena interact - are consistent with other forms of dualist beliefs. In the case of mental disorder treatments, for example, people might think that therapy doesn't help schizophrenia because therapy is inherently a psychological treatment that impacts psychological phenomena, but has less impact on the biological brain problems that cause this disorder. Similarly, medication may be thought ineffective 9

Beliefs About Mental Disorders for adjustment disorder because drugs are a biological treatment that affect the brain, but have less impact on the more psychological issues that are thought to be at the root of this condition. Thus, although the majority of people likely understand that psychological phenomena are realized in the brain, they might still be swayed by the inclination to think of biological and psychological domains as different causal systems. Indeed, there has been considerable speculation that lay theories about the mind and brain may be in some way dualist. Bloom (2004) has suggested that, like Descartes, we are all common-sense substance dualists and see the mind and brain as separate entities (see also Greene & Cohen, 2004; Robbins & Jack, 2006). Although we may understand that these separate entities interact to produce behavior, the mind is thought of as a non-corporeal 'ghost' in the corporeal brain 'machine'. In fact, there does seem to be some evidence that children might be substance dualists. Although even young children know that the mind and the brain are both located in the head, they seem to regard them as independent entities and deny the basic supervenience principle that the mental realm depends on the physical realm. Over 70% of children in the first grade believe that you can have a mind without a brain, and a brain without a mind. Though this decreases with age, by the ninth grade still over 40% of adolescents endorse this claim (Johnson & Wellman, 1982). Similarly, studies asking children about hypothetical brain transplants show that kindergartners and first graders do not yet understand the dependence of the mind on the brain (nor the role of brain in mental life). Children believe a pig with their brain would not retain their identity, preferences, or memories. Instead, children seven years and 10

Beliefs About Mental Disorders younger regard the brain as generally important for mental activity but not containing thoughts and memories (Gottfried, Gelman, & Schultz, 1999; Johnson, 1990). In adults, evidence of dualism is more anecdotal than experimental, and might be reflective of milder forms of rather than true substance dualism. To the extent that people believe in out-of-body experiences, they must posit there is a mind or soul that is independent from the body (Metzinger, 2005). However, it is not clear what percentage of the public believes in such experiences. Similarly, Bloom and Weisberg (2007) note that debates about embryos, fetuses, and stem cells reflect public belief in dualism as they often revolve around whether such entities possess souls. Finally, Greene and Cohen (2004) speculate that the public's interest in fMRI research highlighting where psychological functions take place in the brain may result from an intuitive assumption that decision-making takes place in the mind, not in the brain. There is experimental evidence that children and adults believe that many psychological states, and even life itself, can survive the death of the body (Bering, 2002; Bering & Bjorklund, 2004; Bering, Hernandez-Blasi, & Bjorklund, 2005; Harris & Gimenez, 2005). Although this is consistent with the possibility people believe in an immaterial soul separate from the brain, there is debate as to whether such beliefs reflect more general cognitive tendencies such as an inability to simulate (Bering, 2006) or a tendency to believe in the persistence of a variety of entities through radical changes (Newman, Blok, & Rips, 2006). Given this work suggesting people endorse some forms of dualist beliefs, in Studies 2 and 3 I explore the possibility that such beliefs might underlie intuitions about the effectiveness of mental disorder treatments. In Study 2,1 ask participants to what 11

Beliefs About Mental Disorders degree they believe therapy and medication affect the mind and the brain. I consider whether participants' responses are consistent with different materialistic philosophical theories discussed above (type identity theory, supervenience theories) and whether they also might reflect dualist forms of reasoning. I contrast this task with a question that asks people to explicitly state whether they endorse mind-body dualism or think the mind depends on the brain. In Study 3,1 search for more direct evidence that people might have dualist intuitions of some type. I present participants with mental disorder vignettes and examine if they are willing to agree with statements that deny supervenience and imply that the mind's activities are not dependent on the brain. Clinicians' Beliefs About Causes and Treatments of Mental Disorders While Studies 1 through 3 explore evidence for, and a possible intuitive dualist explanation of, laypeople's beliefs in the differential effectiveness of medication and therapy for different disorders, Studies 4 and 5 examine such beliefs among professional mental health clinicians. If mental health clinicians also have systematic beliefs about the effectiveness of therapy and medication this could have considerable impact in how they approach and treat their clients' disorders. Although there has been some study of clinicians' causal beliefs about disorders, there have been few that have examined treatment beliefs in light of presumed causes. Kim and Ahn (2002) found clinicians' beliefs about what features of a disorder are causally central predict their diagnoses of hypothetical patients, but did not examine any impact of these features on treatment decisions. Two studies have also examined clinicians' causal beliefs about disorders and found that, to the degree disorders are 12

Beliefs About Mental Disorders regarded as biologically based, they are regarded as less psychologically based (Ahn & Flanagan, in preparation; Miresco & Kirmayer, 2006). Although this has been shown to impact the degree to which patients are held responsible and blamed for their actions, implications for treatment have not yet been investigated. One study on clinicians' beliefs about disorders, however, suggests that beliefs about causes may not be related to beliefs about treatment. Ahn, Flanagan, Marsh, and Sanislow (2006) found that clinicians are unwilling to endorse the idea that mental disorders are real and natural categories with necessary and sufficient features that cause symptoms, but rather that mental disorders are invented by and decided upon by experts. Importantly, even those who did endorse such causal essences for mental disorders did not believe that these causes needed to be removed in order to get rid of the disorder, suggesting that perhaps clinicians would not take causes into account when selecting treatments. However, to more rigorously examine if clinicians also prefer within-domain cures, in Study 4,1 explore clinicians' causal beliefs about mental disorders to identify biological and psychological causes of nine common mental disorders. I use this information in Study 5 to present clinicians with cases of mental disorders caused by plausible biological factors and cases caused by psychological factors. I then compare ratings of how effective they think medication and therapy would be at treating these two types of cases. Finally, I close by discussing the larger implications of within-domain treatment preferences for cognitive and clinical psychology. 13

Beliefs About Mental Disorders Study 1: Undergraduates' Beliefs About the Causes and Cures of Mental Disorders In an age in which psychiatric medications are prescribed to treat a broad array of mental disorders and studies have shown that various therapies are effective at treating a wealth of disorders, do people believe that 'cross-domain' treatments are less effective? Study 1 was designed to examine if undergraduates have the intuition that therapy and medication are most effective at treating disorders caused by psychological and biological factors respectively (i.e. that such within-domain cures are more effective than cross-domain cures). Although there is some preliminary evidence of such a cause-treatment link, past research has been hampered by inadequate designs or ones that induce experimental demand. For example, Iselin and Addis (2003) gave participants vignettes describing depression and manipulated whether the character's problems were caused by physical (low levels of serotonin) or psychological causes (got a bad job evaluation), or whether no mention of etiology was made. They found that medical treatments were believed to be more helpful in the physical cause condition, and psychological treatments in the psychological cause condition. However, we cannot draw strong conclusions from this study as this was a within-subjects design, and explicitly telling participants about the cause of a disorder created considerable experimental demand for subjects to rate the matching cure as effective, which could account for the results. Other studies have shown a link between causes and cures without manipulating the causal information given. Instead, participants were asked to rate the importance of 14

Full document contains 145 pages
Abstract: Mental disorders are a major public health concern, and knowing how people think about their causes and treatments can help ensure the success of public education efforts. In the current studies, I examine beliefs about the biological and psychological causes of mental disorders and how they relate to beliefs about the effectiveness of medication and therapy at treating different disorders. In Study 1, I found a systematic preference for within-domain cures among undergraduates: the more a mental disorder is regarded as biologically caused, the more effective medication is thought to be at treating it, with the opposing trend for psychotherapy. The opposite pattern of treatment preferences was found for disorders thought be psychologically caused. In Study 2, I examined beliefs about how treatments affect the mind and brain, and find that undergraduates and adults believe therapy actually has more effect on the mind than the brain, and medication has more effect on the brain than the mind. This systematic pattern suggests that people might be swayed by dualist forms of reasoning, in which they think of biological and psychological phenomena as largely separate and causally distinct domains. Consistent with this idea, in Study 3, I found that people are willing to agree that the symptoms of more psychologically-caused disorders are less a reflection of brain-functioning than more biologically-caused disorders. In Study 4, I examined clinicians' causal beliefs about disorders and found that though they acknowledge all disorders are caused by both biological and psychological factors, the relative importance of each type of cause varies across disorders. Finally, in Study 5, I found that similar to undergraduates, clinicians believe that cases of a mental disorder caused by biological factors are thought more treatable by medication than cases of the same disorder caused by psychological causes. I discuss whether such beliefs about treatment are normative, their possible impact on adherence to prescribed treatments, and the implications of causal beliefs for attitudes, blame, and sympathy for those suffering from mental disorders.