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(p. 121) The puzzle of paranoia 

(p. 121) The puzzle of paranoia
(p. 121) The puzzle of paranoia

Daniel Freeman

, Philippa Garety

, and David Fowler

Page of

date: 23 May 2018

You can look at a piece of a puzzle for three whole days, you can believe that you know all there is to know about its colouring and shape, and be no further on than when you started. The only thing that counts is the ability to link this piece to other pieces. The pieces are readable, take on a sense, only when assembled; in isolation, a puzzle piece means nothing—just an impossible question, an opaque challenge.

G. Perec (1978), p. xv


The first commercial jigsaw puzzle, created in the eighteenth century, was of a map of the world. There is no such guide picture for helping to understand paranoid experience. Therefore we will begin this chapter by describing the puzzle that needs to be solved. Then we will lay out the pieces which have been found so far. Implicit in this approach is the idea that paranoid thinking needs to be understood in terms of multiple factors. No single cause of paranoia will be found. Our initial attempt to assemble the pieces—the ‘threat anticipation cognitive model’—will be presented. However, this model only identifies the corner pieces of the puzzle, at best. We therefore also outline potential pieces worthy of inspection, promising methodologies, and key questions to guide future research.

The complexity of the paranoid picture

Delusional experience is clearly multi-dimensional. This has been learned from debates on defining delusions (e.g. Strauss 1969; Garety 1985; Oltmanns 1988), (p. 122) factor analytic studies of patients’ experiences (e.g. Kendler et al. 1983; Harrow et al. 1988; Garety et al. 1988), and evidence that response to treatment varies across the different dimensions (e.g. Trower et al. 2004; Mizrahi et al. 2006). Key dimensions include level of belief conviction, degree of preoccupation, and extent of distress. The important implication is that multiple questions should be asked about paranoid experience: what causes thoughts of an unfounded paranoid content, when does a paranoid thought capture a person’s attention, what causes the thought to become held as a belief, why does resistance to change occur, how does the thought become distressing, and why does it impact on day-to-day life? Many of these questions may sub-divide when brought into focus. For example, persecutory thinking contains two key elements: the individual believes that harm is occurring, or is going to occur, to him or her, and that the persecutor has the intention to cause harm (Freeman and Garety 2000). Therefore it is reasonable to ask: are there separate processes involved in the development of ideas about threat and of ideas about others’ intentions? In other words, how does an anxious thought turn into a paranoid thought? But it is also important to stand back from the detail and view the wider picture. The most striking findings here are the relatively high frequency in the general population of paranoid thoughts and their continuous distribution across the population (e.g. van Os et al. 2000; Freeman et al. 2005a). This raises two questions: what is the function of paranoid thought and what is the relationship between clinically severe and non-clinical everyday paranoid experience? The number of questions listed illustrates the complexity of the paranoid picture and points towards the likelihood that multiple factors will be invoked in answering them.

(Some of the) pieces of the puzzle: psychological factors and persecutory ideation

The recent psychological approaches to paranoia make plausible connections to the experiences reported by patients. The explanations often have face validity. This is a helpful step before empirical testing. We highlight the plausible factors that have research evidence to support them. For a detailed review of this literature see Freeman (2007). There are caveats to keep in mind: the psychological processes have not been evaluated equally; some factors have been investigated in relation to delusions in general rather than persecutory ideation specifically; and most studies do not control for the common co-occurrence of symptoms found in clinical settings (Maric et al. 2004) so that spurious associations with paranoia might have been found.

(p. 123) Anxiety

Our contention has been that a key piece of the puzzle is anxiety, since paranoia concerns fear. Persecutory and anxious thoughts both concern the anticipation of threat; fears of physical, social or psychological harm are apparent both in anxious thoughts (e.g. Eysenck and van Berkum 1992; Wells 1994) and in persecutory thoughts (Freeman and Garety 2000; Freeman et al. 2001). It is argued that anxiety helps to create thoughts of a paranoid content. Anxiety has repeatedly been found to be associated with paranoid thoughts (e.g. Martin and Penn 2001; Johns et al. 2004) and persecutory delusions (e.g. Freeman and Garety 1999; Startup et al. 2007) and it is predictive of the occurrence of paranoid thoughts (Freeman et al. 2003, 2005b, 2008; Valmaggia et al. 2007) and of the persistence of persecutory delusions (Startup et al. 2007). Moreover, it has been shown in non-clinical groups that paranoid thoughts build upon common interpersonal anxieties and worries such as fears of rejection (e.g. Freeman et al. 2005a,b). Anxiety is apparent in many patient accounts, for example, Kristen Fowler’s (2007) description of the early stages of her psychosis: ‘In darkened spaces, I feel a presence is lurking; I fear that it is watching me. I don’t like to think about what it might be, but I think it’s something dead, something that is alive and yet shouldn’t be alive. Something silent, stealthy, evil, made of bones, or bloody, decaying body parts. I am terrified to look in the closets, or behind doors, or in the garage. I am constantly turning my head to look behind me. Even a familiar sound such as the cat jumping off the counter startles me. My heart pounds while the water sprays over me in the shower, for fear that my eyes might be closed or my back turned and my body vulnerable as something advances toward me.’

Paranoid thinking and anxiety-related processes have been linked. Initial evidence indicates that almost two-thirds of individuals with persecutory delusions have a thinking style characterized by worry (even about matters unrelated to paranoia) (Freeman and Garety 1999; Startup et al. 2007). Worry in individuals with paranoia is associated with more catastrophic delusion content, higher levels of distress and with delusion persistence. Worry is likely to be an important process in understanding paranoia (Freeman et al. in press). Other anxiety-related processes are also apparent in people with persecutory delusions. An example is safety behaviour (Freeman et al. 2001, 2007). Individuals who feel threatened often carry out actions designed to prevent their feared catastrophe from occurring; this has been termed ‘safety behaviour’ (Salkovskis 1991). When the perceived threat is a misperception, such as in anxiety disorders and paranoia, there are important consequences. Individuals fail to attribute the absence of catastrophe to the incorrectness of (p. 124) their threat beliefs. Rather, they believe that the threat was averted only by their safety behaviours (e.g. ‘The reason I wasn’t attacked was because I left the street in time and made it back home’). Conviction in threat beliefs is likely to persist partly due to this failure to obtain and process disconfirmatory evidence.

Negative beliefs about self and others

It is a reasonably common concern to have ideas that the self is weak, foolish, unloved, different or misunderstood. Paranoid thoughts may be an anxious extension of such ideas. Negative beliefs about the self may be a first step to thinking about being a vulnerable target for others to mock, exploit or harm. This may be especially likely when negative ideas about others are also held, for example, that people are generally bad, selfish, or devious. In what is likely to prove a key paper, Fowler et al. (2006a) found that in a non-clinical population of more than 700 students paranoia was associated with negative beliefs about the self, negative beliefs about others, less positive beliefs about others, and anxiety. Self-esteem as traditionally measured was not as good a predictor of paranoia and, unlike schematic beliefs, did not discriminate between the non-clinical group and a group of 250 patients with psychosis. A related study of 100 patients with psychosis found that the severity, preoccupation and distress of persecutory delusions were associated with negative beliefs about the self, negative beliefs about others, low self-esteem and depression (Smith et al. 2006). These findings are consistent with a wider literature indicating an association of affective problems with the positive symptoms of psychosis (e.g. Norman and Malla 1994; Guillem et al. 2005) and evidence that low self-esteem predicts the later development of positive symptoms of psychosis (Krabbendam et al. 2002). The view that paranoid thoughts build on conscious negative thoughts about the self is the opposite of delusion-as-defence accounts in which paranoid thoughts are believed to suppress unconscious low self-esteem.

Adverse events and trauma

An obvious potential factor is past experience: previous experience of negative intent from others is likely to mean that explanations concerning hostility are more forthcoming in the future. The unfortunate implication is that being bullied or victimized may bias towards the negative future interpretations of others’ behaviour. There has been renewed interest in the topic of trauma and psychosis, following repeated reports of an association (e.g. Fowler 1997; Fowler et al. 2006b; Read et al. 2005; Larkin and Morrison 2006). For example, in the 2000 British National Survey of Psychiatric Morbidity of more than (p. 125) 8000 respondents, a history of victimization experiences was significantly associated with paranoid thoughts (Johns et al. 2004). In a survey of more than 10 000 Australians, all types of trauma, but especially rape, were associated with delusional ideation, and a dose–response relationship was found (i.e. those who had been exposed to a greater number of different types of trauma were more likely to report delusions) (Scott et al. 2007). In a cross-sectional study of 200 students, Gracie et al. (2007) found that a history of childhood trauma, sexual abuse or physical assault was associated with raised levels of paranoid thinking. Further, analysis indicated that negative beliefs about the self and others may be a mediating factor between traumatic reactions and paranoid thinking. Selten and Cantor-Graae (2005) argue, on the basis of findings of higher rates of psychosis in those brought up in urban areas and migrant groups, that chronic and long-term experience of ‘social defeat’ is a risk factor for schizophrenia. It seems plausible that negative past experience—via its affective impact—is a piece in the puzzle of understanding paranoid experience.

Puzzling experiences

Maher (1974, 1988) emphasizes that delusional ideas spring from unusual internal experiences. This is consistent with findings that many people with psychosis have clear anomalous experiences such as hallucinations, thought insertion, and replacement of will, and also a range of more subtle perceptual and attentional alterations in experience (e.g. McGhie and Chapman 1961; Bunney et al. 1999) and, often, periods of arousal (e.g. Docherty et al. 1978; Hemsley 1994). There are two key points here. The first point is that delusions are explanations of experiences, attempts by individuals to make sense of their experiences. The second point is that odd experiences may lead to odd ideas. Other theorists have speculated similarly. Kapur (2003) has highlighted the importance of aberrant feelings of salience in delusion formation, which is particularly of note since in this account the abnormal experience itself concerns processes of meaning ascription. A tradition in German psychiatry is to study anomalies of experience (‘basic symptoms’) for which ‘delusions may provide new elaborative contexts to understand the dislocated or overly salient perceptual fragments’ (Uhlhaas and Mishara 2007). Explanations for anomalies of experience include core cognitive dysfunction (e.g. Hemsley 1994), impairment in early stage sensory processing (e.g. Butler and Javitt 2005), illicit drug use (e.g. D’Souza et al. 2004), and hearing impairment (e.g. Zimbardo et al. 1981). In one study it has been found that predisposition to hallucinatory experience differentiated the prediction of paranoid from anxious thoughts (Freeman et al. 2005b).

(p. 126) Reasoning

If delusions are incorrect—or perhaps, more importantly, uncorrected— beliefs, then judgemental or reasoning processes are inherently implicated in their cause. A number of researchers have therefore tried to identify biases or deficits in reasoning in individuals with paranoia. The most convincing empirical evidence is that a significant proportion of individuals with delusions are hasty in their data-gathering (‘jump to conclusions’), which is hypothesized to lead to the rapid acceptance of beliefs even if there is limited evidence to support them (e.g. Garety and Freeman 1999; Garety et al. 2005; van Dael et al. 2006; Fine et al. 2007). There is also evidence that the biases in reasoning may be much more subtle outside of acute delusional states (Freeman et al. 2005b; van Dael et al. 2006). Probabilistic reasoning has rarely been studied in relation to delusion sub-type. Only the limited conclusion can be made that jumping to conclusions is often present in people with persecutory delusions (Freeman 2007). In clinical groups there is also evidence that individuals with delusions have ‘belief inflexibility’, defined as difficulties in reflecting on one’s own beliefs and to consider alternative ideas, which may lead to delusion persistence (Garety et al. 1997, 2005; Freeman et al. 2004). Interestingly, Chapman (2002) describes how he reversed such reasoning biases to quell his delusions: ‘The belief stayed fixed until I researched and found sceptical debunking counterarguments and disconfirming evidence. Overcome by the stranglehold of delusions, I fought almost unceasingly for the troops of reality to save me. If reality was a door, I could say I knocked on it 10 000 times while I trembled in fear, unshielded from the barrage of imaginary horrors that surrounded me.’


Frequently, when talking to patients, a richness in the content of their persecutory fears is obviously apparent. Some aspects of the situation seem to cause more distress than others. The basic cognitive model in which emotion is linked to beliefs provides an ideal way to understand this. Chadwick and Birchwood took such an approach to show that there are commonalities in the most distressing aspects of hallucinatory experience (e.g. Chadwick and Birchwood 1994; Birchwood et al. 2000). Following this work, we examined whether there were particular parts of the content of persecutory delusions that are most distressing (Freeman et al. 2001). Higher levels of depression were associated with higher ratings of the power of the persecutor, a lower sense of control over the situation, ideas about the inability to cope if the threat materialized, and believing that the persecution was deserved. There were indications that higher levels of anxiety may be associated with feeling (p. 127) under constant threat and that there was no chance of rescue from the threatening situation. We postulated that prior emotional distress influences the content of delusions and that delusion content in turn influences level of emotional distress. Subsequent studies have confirmed content and distress links in paranoid experiences (Chisholm et al. 2006; Green et al. 2006). An alternative account of Trower and Chadwick’s (1995) distinction between ‘poor me’ and ‘bad me’ paranoia is that the concept of deservedness is a (dimensional) aspect of the content of paranoia associated with distress, but not an indicator of discrete categories with opposite causes. It is also likely that further reflection about what is happening—how people understand their difficulties—influences the emotional reaction. There is an emerging and important literature in which self-appraisals of illness/problems—concerning, for example, cause, course, outcome, loss, entrapment, and humiliation—are associated with levels of depression, anxiety and self-esteem in schizophrenia (e.g. Rooke and Birchwood 1998; Lobban et al. 2003; Watson et al. 2006).

Pieces of other puzzles?

There are two psychological processes well-researched in regard to paranoia that, in our view, have equivocal empirical support: attributional style and ‘theory of mind’ (ToM). Different evaluations of the literature are provided in Chapters 8 and 10 of this book. We therefore describe the evidence base here in a little more detail.

If a person tends to explain negative events in terms of other people (i.e. has a particular attributional style) then this would certainly be a plausible factor in the creation of paranoid thoughts. Most attribution studies have used either the Attributional Style Questionnaire (ASQ) (Peterson et al. 1982) or the Internal, Personal and Situational Attributions Questionnaire (IPSAQ) (Kinderman and Bentall 1996a). Three ASQ studies (Lyon et al. 1994; Fear et al. 1996; Krstev et al. 1999) show clear evidence of an externalizing bias for negative events in people with persecutory delusions compared with non-clinical controls and two ASQ studies find no differences between persecutory delusion and non-clinical control groups (Kinderman et al. 1992; Martin and Penn 2002). None of the four IPSAQ studies find evidence of an externalizing bias for negative events in persecutory delusion groups compared with non-clinical controls (Kinderman and Bentall 1996b; Martin and Penn 2002; (p. 128) Randall et al. 2003; McKay et al. 2005). In the first clinical study using the IPSAQ, Kinderman and Bentall (1996b) found that, when external attributions were made, individuals with persecutory delusions were more likely to make external– personal attributions compared with non-clinical controls. However, in three further clinical studies this has not been replicated (Martin and Penn 2002; Randall et al. 2003; McKay et al. 2005). Therefore, the empirical case for persecutory delusions being associated with an excessive externalizing style for negative events is unconvincing at present. Attributional style may be more closely tied with affective state (see Jolley et al. 2006).

Individuals with persecutory ideation are by definition sometimes misreading the intentions of other people. Therefore Frith (1992, 2004) proposes that symptoms of schizophrenia develop from newly acquired difficulties in ToM abilities, the mechanism of determining others’ mental state. Persecutory delusions are hypothesized to arise because the person notices that other peoples’ actions have become opaque and surmises that a conspiracy exists. The empirical evidence indicates that ToM difficulties are apparent in people with a diagnosis of schizophrenia, but may be most severely present in individuals with negative symptoms and incoherent speech (Sarfati et al. 1997; Garety and Freeman 1999; Brüne 2005; Harrington et al. 2005a; Freeman 2007). Indeed, this association with negative symptoms may be expected from the neuropsychological literature; ToM tasks and executive functioning have been found to be linked in the developmental psychology literature (e.g. Hughes 2002) and executive functioning difficulties have been found to be associated with negative symptoms and thought disorder but not the positive symptoms of psychosis (e.g. O’Leary et al. 2000). Six studies have examined correlations with paranoid symptom assessments. Four found no association of paranoia and ToM abilities (Langdon et al. 1997, 2001; Blackshaw et al. 2001; Greig et al. 2004) and two studies did find an association (Craig et al. 2004; Harrington et al. 2005b). The study of Greig et al. (2004) is the largest study of ToM in schizophrenia and best addresses the question of ToM and psychotic symptoms. A sample of 128 outpatients with schizophrenia were assessed on the ability to understand hints. It was found that ToM performance was associated with thought disorder. An interesting study by McCabe et al. (2004) also merits note. They argue that if ToM difficulties are present in individuals with schizophrenia then they should be detectable in real-life social interactions. These researchers found that outpatients with positive and negative symptoms of schizophrenia actually showed intact ToM skills in conversations with mental health professions.

The threat anticipation model of persecutory delusions

The pieces of the puzzle that we judge important to the psychological understanding of persecutory ideation are: anomalous experiences, such as hallucinations and perceptual anomalies, which may be caused by core cognitive dysfunction and street drug use; affective processes, especially anxiety, worry, and interpersonal sensitivity; reasoning biases, particularly jumping to conclusions, (p. 129) and belief inflexibility; and social factors, such as adverse events and environments. These have been assembled into the threat anticipation model of paranoia (Fowler 2000; Garety et al. 2001; Freeman et al. 2002; Freeman and Garety 2004; Freeman 2007; Freeman and Freeman 2008). The model is explicitly built on the idea that there are multiple factors responsible for the development and maintenance of paranoia. Further, the model addresses the multi-dimensional nature of persecutory experience, highlighting specific factors for the development of delusion content, conviction, persistence, and distress (see Figures 7.1 and 7.2).

Fig. 7.1 Outline of factors involved in persecutory delusion development.

Fig. 7.1
Outline of factors involved in persecutory delusion development.

Fig. 7.2 Outline of the maintenance of a persecutory delusion.

Fig. 7.2
Outline of the maintenance of a persecutory delusion.

Delusion formation

Following the influential work of Maher (1974), delusional beliefs are considered as explanations of experience. The sorts of experiences considered as the proximal source of evidence for persecutory delusions are:

  • Internal feelings. Unusual or anomalous experiences are frequently key to delusional ideation. These include: being in a heightened state/aroused; having feelings of significance; perceptual anomalies (e.g. things may seem vivid or bright or piercing, sounds may feel very intrusive); having feelings as if one is not really there (depersonalization); and illusions and hallucinations (e.g. hearing voices). These sorts of experiences can be caused by (p. 130) the processes hypothesized by theorists such as Hemsley (1994) or Kapur (2003), by the use of street drugs or by high levels of affect.

  • External events. Ambiguous social information is particularly important. This includes both non-verbal information (e.g. facial expressions, people’s eyes, hand gestures, laughter/smiling) and verbal information (e.g. snatches of conversation, shouting). Coincidences and negative or irritating events also feature in persecutory ideation.

In essence, the person feels different and this needs an explanation. Typically, individuals vulnerable to paranoid thinking try to make sense of internal unusual states by drawing in negative, discrepant, or ambiguous external information. For example, a person may go outside feeling in an unusual state and, rather than label this experience as such (e.g. ‘I’m feeling a little odd and anxious today, probably because I’ve not been sleeping well’), the feelings are instead used as a source of evidence, together with the facial expressions of strangers in the street, that there is a threat (e.g. ‘People don’t like me and may harm me’).

But why a suspicious interpretation of experiences? The internal and external events are interpreted in line with previous experiences, knowledge, emotional state, memories, personality, and decision-making processes and therefore the origin of persecutory explanations lies in such psychological processes.

Emotion is key, especially anxiety. Suspicious thoughts often occur in the context of emotional distress, frequently triggered by stressful events (e.g. difficult interpersonal relationships, bullying, isolation). The stresses will have a (p. 131) greater impact if they occur against a background of previous adverse experiences that have led the person to have negative beliefs about the self (e.g. as vulnerable), others (e.g. as potentially dangerous), and the world (e.g. as bad). Negative beliefs about the self and others are associated with anxiety and depression, but anxiety may be especially important in the generation of persecutory ideation. The theme of anxiety is the anticipation of danger and it is the origin of the threat content in persecutory ideation. Paranoid thoughts are an anxious extension of the negative ideas about the self and others. Moreover, it is unsurprising that paranoid thoughts pass through the mind, since the decision whether to trust or mistrust is at the heart of all social interactions, and is often a difficult judgement to make and therefore prone to errors. Anxiety may be fleeting in the generation of a paranoid thought, but paranoid thoughts will be more significant in the context of higher levels of trait anxiety. Paranoid thoughts are hypothesized to have close links with anxiety processes. For example, worry may keep the suspicions in mind and develop the content in a catastrophizing manner. Hence in the model emotion is given a direct role in delusion formation.

The persecutory ideas are most likely to become of a delusional intensity when there are accompanying biases in reasoning such as reduced data gathering (‘jumping to conclusions’) (Garety and Freeman 1999), a failure to generate or consider alternative explanations for experiences (Freeman et al. 2004), and a strong confirmatory reasoning bias (Freeman et al. 2005c). Social isolation may also contribute to a failure to fully review paranoid thoughts. When reasoning biases are present, the suspicions are more likely to become near certainties; the threat beliefs become held with a conviction unwarranted by the evidence and may then be considered delusional.

Delusion maintenance

Maintaining factors can be divided into two types: those that result in the obtaining of confirmatory evidence and those that lead to disconfirmatory evidence being discarded. There are a number of ways in which confirmatory evidence is obtained. The normal belief confirmation bias will operate: individuals will look for evidence consistent with their beliefs. The confirmation bias may be particularly strong in individuals with delusions. Persecutory delusions are viewed as explanations that contain threat beliefs about physical, social, or psychological harm. Therefore, attentional biases will come on-line, as is found in emotional disorders: threat will be preferentially processed (Bentall and Kaney 1989); threatening interpretations of ambiguous events will be made; and such biases are likely to be enhanced by a self-focused cognitive style (Freeman et al. 2000). Memory biases will lead to frequent presentations of (p. 132) the evidence for the delusion in the mind of the individual. Continuing anomalous experiences (often triggered by anxiety) will also provide powerful evidence consistent with the threat belief. Finally, the person’s interactions with others may become disturbed. The person may act upon their delusion in a way that elicits hostility or isolation (e.g. by being aggressive, or treating others suspiciously), and they may suffer stigma (Wahl 1999). In essence, others may act differently around the person, or break contact with them, thus confirming persecutory ideas.

But why does the persecutory belief remain for such a length of time when the predicted harm has not actually happened? Potentially disconfirmatory evidence is discarded in two main ways. The first main way is by the use of safety behaviours. Individuals with persecutory delusions take actions designed to reduce the threat, but which actually prevent disconfirmatory evidence being received or fully processed. The second way in which disconfirmatory evidence may be discarded is by incorporating the failure of predicted harm events into the delusional system. Attributes of the persecutor (e.g. the deviousness of the persecutors, their cruelty, occasionally their limited powers) or the situation (e.g. others are protecting them, luck has been on their side) may be considered as explaining the non-occurrence of harm. As well as this accommodation within the delusional system, disconfirmatory evidence may simply be disregarded because no alternative explanation for the delusional experiences is available.

Delusion distress

At the simplest level, emotional experiences are directly associated with the content of delusional beliefs. The cognitive content of emotions will have been expressed in the delusions and, in turn, the content of the delusions will contribute to the maintenance and exacerbation of the emotion. So, for example, anxiety will directly result from the threat belief. The threat belief will re-affirm and exacerbate previously held ideas about vulnerability and hostility. Levels of anxiety and distress will be higher for individuals who believe that the harm will be extremely awful, that it is very likely to occur, and who feel under constant threat (24 h a day). Depression will be associated with delusion content about the power of the persecutors and whether the persecution is deserved punishment. If persecutors are believed to be extremely powerful, this will reinforce and increase depression.

Emotion is also generated from further appraisal, in relation to the self, of the contents of the delusional belief and of the actual delusional experience itself. Depression will result from negative appraisals of the delusion or delusional thoughts (e.g. that the persecution or persecutory thoughts are a sign of (p. 133) failure or badness). For some individuals, the negative beliefs about the self are long-term, precede delusion formation, and were already reflected in the contents of the delusion. However, for other individuals appraisal of the delusion can trigger such negative beliefs. Depression will also occur if individuals believe upon reflection that they have no control over the persecutory situation, and that this seems to be true of many areas of their lives. Additional anxiety may result from appraisals concerning vulnerability, hostility, and danger. Delusional distress will be associated with appraisals of the experience of delusional thoughts. Higher levels of delusional distress are associated with worries about a lack of control of persecutory thoughts. Contributing to these feelings of uncontrollability will be the counter-productive use of thought-control strategies. Finally, negative appraisal of the problems (or of illness) will lead to greater emotional distress. For example, individuals who appraise their problems as completely uncontrollable, likely to last a long time, a significant impediment to work, and as embarrassing, are likely to feel depressed.

Future research

The research area is at an early stage of development. Even the pieces of the puzzle identified so far require further empirical scrutiny. Can it be shown that the psychological factors are causal in paranoid thinking? Can it be shown that the factors explain significant amounts of the variance in paranoid thoughts (i.e. that the factors are important)? Do these factors interact in the development of paranoia? There are then questions to further the theoretical understanding: What factors distinguish the development of persecutory ideation from the development of grandiose (or other types of) delusional ideation? What distinguishes the development of paranoid from anxious fears? How do the psychological processes relate to social and biological factors (see Garety et al. 2007)?

Taking the last of these questions, there is the possibility of an exciting line of research into the understanding of the psychological impact of social factors. McGrath (2007) has recently highlighted ‘the surprisingly rich contours of schizophrenia epidemiology’. There is robust evidence of increased rates of psychosis being associated with social factors such as urban environments (e.g.Marcelis et al. 1998), lower socio-economic status (e.g.Wicks et al. 2005) and migrant status (e.g. Kirkbride et al. 2006). Their impact on paranoid experiences or on psychological processes is much less established. In the Camberwell Walk Study, we examined the clinical and psychological impact on people with persecutory delusions of entering a deprived urban area (Ellett et al. 2008). Thirty patients with persecutory delusions were randomized to exposure to a deprived urban environment or to a brief mindfulness relaxation task. (p. 134) After exposure, assessments of symptoms, reasoning, and affective processes were taken. Spending time in an urban environment made the participants more paranoid and anxious. Compared with relaxation, walking in the main shopping street of Camberwell made patients think more negatively in general about other people and increased the jumping-to-conclusions reasoning bias. There are methodological challenges in this area, but the study indicates that a number of processes hypothesized to lead to paranoid thoughts are exacerbated by entering a deprived urban environment.

Innovative methodologies are clearly needed. We have recently developed an experimental method, using virtual reality, to study unfounded persecutory ideation (Freeman et al. 2003, 2005b, 2008; Valmaggia et al. 2007; Freeman in press). The key to this work is that virtual reality enables individuals to experience an identical controlled situation. This provides a means of investigating variation in interpretations. In applying this method to the study of persecutory ideation, participants experience a neutral social event (e.g. tube train, library). The computer characters (‘avatars’) are programmed to exhibit only behaviour that most people would assess as neutral (and the avatars certainly have no hostile intentions). Individuals’ appraisals of the avatars are then assessed. Most people have positive or neutral appraisals of the characters. However, a significant minority have paranoid interpretations, which are clearly unfounded. Not only is it known that paranoid thinking in the virtual environment is unfounded but the person’s behaviour cannot elicit hostile or negative reactions from the characters. This methodology is likely to prove crucial not only in establishing predictors of paranoid thinking but in establishing causal roles of psychological variables. In the longer term, virtual reality may even be used in treatments.

It should be recognized that a multi-factorial perspective provides difficulties for empirical investigations. If a factor is neither necessary nor sufficient, then it may be infrequent. As such, empirical evidence for its importance may not be easily obtained (false negative). If multiple factors are assessed, there is an increased risk of obtaining a statistically significant result by chance (false positive). If interactions are hypothesized between factors, large data-sets are needed to achieve statistical power. There is also the danger that multi-factorial models become over-inclusive in order that any results can be accommodated. The models can be difficult to disprove. Our strategy has been to investigate factors that we think are of particular importance (i.e. occur in a significant proportion of individuals). Another strategy is to conduct stepwise investigations of the cognitive processes in a multi-factorial model by choosing control groups matched for some of the identified factors (see Table 7.1). We also note that studies of delusions dimensionally in non-clinical groups enable recruitment of a larger number of participants than is possible for studies of clinical (p. 135) (p. 136) populations and therefore provide a better means of testing complex models. Furthermore, studying single dimensions of delusional experience will simplify the theoretical and practical challenges.

Table 7.1 Control groups that can strengthen study designs (Freeman and Garety 2004)

Topic addressed

Comparison groups


Maintenance factors

Persistent vs acute groups

Cognitive processing can be compared between individuals whose symptoms are known to persist and individuals whose symptoms naturally recover quickly. This is informative about maintenance factors. Previous studies have tended to group these individuals together which might have obscured identification of maintenance factors.

State/Trait factors

Delusion vs recovered group

Whether factors are state or trait variables can be examined with this study design. However, it is possible that key processes are latent, in which case mood induction procedures may also be necessary.

Factors specific to delusions

Delusions in disorders other than non-affective functional psychosis vs individuals with the same diagnosis but no delusions

Studying delusions in, for example, affective psychosis enables recruitment of a closely matched control group (e.g. individuals with depression but no delusions). Factors that are specifically associated with the delusion presentation can be identified. Ideally this should be carried out across affective, non-affective, and organic conditions so that the relevant importance of factors can be assessed.

Factors specific to persecutory delusions

Persecutory delusions vs other delusions group

Cognitive processing by individuals with persecutory delusions could be compared with individuals with grandiose delusions. Factors specific to persecutory delusions, rather than delusions in general, could be identified.

Similarities and differences with neurosis

Delusions vs emotional disorder

Cognitive processing can be compared between groups with neurotic and psychotic disorders to identify shared and distinct maintenance factors.

Topic addressed

Comparison groups


Testing the importance of single factors in a multi-factorial model

Delusions vs similar cognitive processing but no delusions group.

Individuals who have cognitive processing identified by the model as involved in delusion development but do not have delusions can form an interesting control group. For instance, individuals who have anomalous experiences or individuals who have a jumping-to conclusions reasoning bias. Differences from a delusion group can identify the additional factors needed for a delusion to develop.

There also needs to be a search for other pieces of the puzzle. For example, are loneliness and social isolation (Heinrich and Gullone 2006; Freeman et al. 2008) important to paranoia? Are everyday processes of trust formation (Crouch and Jones 1997) implicated? And there is still much more to learn about reasoning and delusions. Experimental work is needed on the interaction of the production of potential explanations, data gathering, the processing of confirmatory and disconfirmatory reasoning, the acceptance of explanations, and how beliefs change. Further, how these reasoning elements are modified by current goals, emotional state, and interactions with others needs to be examined. Finally, of course, still remaining is the significant challenge of translating advances in understanding persecutory ideation into improved clinical treatments (Freeman et al. 2006). Once causal roles of psychological variables have been established, it needs to be demonstrated that therapeutic techniques can make an impact on such processes and thereby effect lasting change in paranoid experience. Such work is only now beginning.


Daniel Freeman is supported by a Wellcome Trust Fellowship.


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