Delusions of reference: A new theoretical model
Mike Startup1, Sandra Bucci2, and Robyn Langdon3
1School of Psychology, University of Newcastle, Australia, 2School of
Psychological Sciences, University of Manchester, UK, 3Macquarie Centre for
Cognitive Science, Macquarie University, Australia, and Cognition and
Connectivity Research Panel, Schizophrenia Research Institute, Darlinghurst,
Australia
Introduction. Although delusions of reference are one of the most commonpsychotic symptoms, they have been the focus of little research, possibly becausethey have been considered to be integral to persecutory delusions. Evidence has nowemerged that there are two kinds of delusion of reference. One of these, referentialdelusions of communication, which involves beliefs that others are communicatingin subtle, nonverbal ways, is the focus of this paper.Methods. We present a new model designed to account for the four crucial aspects ofthe phenomenology of these delusions: (1) that neutral stimuli are experienced ashaving personal significance; (2) that the neutral stimuli are experienced ascommunicating a message nonverbally; (3) that the content of the message concernsthe self; (4) that the experience of a self-referent communication is believed ratherthan being dismissed as implausible. We used PsycINFO and Scopus, using the term‘‘delusion* of reference’’, to search for publications with a bearing on our model.Results. The amount of research we found that was designed to test aspects of thismodel is small but other published research appears to provide some support for itsvarious steps. Much of this research was not explicitly intended to provide anaccount of delusions of reference but its relevance nevertheless seems clear.Conclusions. There is preliminary support for the plausibility of our model but muchadditional research is needed. We conclude by summarising what we consider to bethe main desiderata.
Keywords: Aberrant salience; Delusions of reference; Reality discrimination;
Theory of mind.
Correspondence should be addressed to Mike Startup, School of Psychology, University of
Newcastle, Callaghan, NSW 2308, Australia. E-mail: [email protected]
We would like to thank Prof. Nick Tarrier for his comments on an earlier draft of this paper.
COGNITIVE NEUROPSYCHIATRY
2009, 14 (2), 110�126
# 2009 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business
http://www.psypress.com/cogneuropsychiatry DOI: 10.1080/13546800902864229
Interviewer: Have you ever walked into a room and thought people were talking
about you or laughing at you?
Patient: Yeah, sometimes people have got sneering eyes. You can see it. Maybe
it’s a reflection of what I’m thinking in my head, you know what
I mean? You can see it in their eyes. It’s good to be self-conscious
’cause you can catch yourself out and correct yourself. But if it goes
too much you get paranoid in yourself. That’s when the carnival
starts. Oh yeah, that’s when the trickster comes in.
INTRODUCTION
Delusions of reference are said to occur when people mistakenly become
convinced that neutral events, objects, or people in the environment havespecial significance and contain personal relevance to the observer. Clinical
observations have primarily informed definitions of delusions of reference
that are contained in psychiatric textbooks (e.g., Gelder, Gath, & Mayou,
1989) and in semistructured interviews such as the Present State Examina-
tion (PSE; Wing, Cooper, & Sartorius, 1974). According to such sources,
some patients frequently have the mistaken belief that others are commu-
nicating with them by subtle and oblique paralinguistic means, such as
indirect hints or innuendos, or through nonverbal channels, such as gesturesor stances. They may also believe that they are being personally referred to in
the public media or that objects or situations have been purposely arranged
in order to convey a message. Some even have the sense that animals are
communicating implausibly complex messages to them. Other delusions of
reference concern beliefs about being kept under observation. For example,
some patients mistakenly believe that others are surreptitiously observing
them, perhaps by using surveillance equipment or by following them, or that
a large number of strangers are gossiping and spreading rumours aboutthem. Ideas of reference are a milder form in which referential thoughts are
entertained without conviction.
Among these rather disparate delusional beliefs there appears to be a
fundamental distinction to be made between delusions concerning commu-
nication and delusions concerning observation, and this distinction has now
been supported by two factor analyses of interview-based ratings of these
different beliefs (Bucci, Startup, Wynn, Heathcote, et al., 2008; Startup &
Startup, 2005). In both of these studies, delusions that others werecommunicating paralinguistically, nonverbally, through the public media
or via the arrangement of situations all loaded together on one factor, which
Startup and Startup (2005) called referential delusions of communication.
Delusions that others were observing surreptitiously or gossiping loaded on
a separate factor, called referential delusions of observation. The theoretical
DELUSIONS OF REFERENCE 111
account developed later in this paper is primarily concerned with delusions
of communication.
Delusions of reference are traditionally regarded as integral to persecu-
tory delusions (Leon, Bowden, & Faber, 1989). However, referential
delusions are also common in nonpersecutory patients with body dys-
morphic disorder (Phillips, McElroy, Keck, Pope, & Hudson, 1993), theysometimes occur in isolation from any other delusional beliefs, including
persecutory delusions (Startup & Startup, 2005), and they have been
reported in people without any diagnosable psychological disorder (Freeman
et al., 2005), even in children as young as 11 years old (Poulton et al., 2000).
Furthermore, in their analysis of ratings of different kinds of referential
delusion, Startup and Startup found that only referential delusions of
observation were associated with persecutory delusions (and auditory verbal
hallucinations); referential delusions of communication showed few sig-nificant associations with any other positive psychotic symptoms. Thus, it
appears that the traditional association between referential and persecutory
delusions applies primarily to referential delusions of observation.
PREVALENCE
Delusions of reference are one of the most common psychotic symptoms.
For example, they have been found in 67% of people with a diagnosis of
schizophrenia (World Health Organization, 1973), and in 64% of inpatients
suffering from a psychotic disorder (Minas et al., 1992). In the latter study
they were equal in frequency to persecutory delusions (64%), and more
common than auditory hallucinations (50%) or any other positive psychoticsymptom. Boydell et al. (2007) found that 50% of people with a recent first
episode of schizophrenia had delusions of reference. However, all these
studies employed a broad definition of delusions of reference. To date no
systematic study has been conducted into the prevalence of referential
delusions of communication specifically; the best information we have comes
from the studies by Startup and Startup (2005), Bucci, Startup, Wynn,
Heathcote, et al. (2008), and a recent unpublished study by the first author.
Among the combined patients from these studies who had acute psychoticdisorders, 69 out of 143 (48%) had referential delusions of communication.
Among the stabilised outpatient volunteers with schizophrenia in the study
by Startup and Startup, 10 out of 31 (32%) had these delusions.
AIMS OF THE PRESENT PAPER
Despite the prevalence of delusions of reference, very little research has been
focused on them. This is surprising since the single-symptom approach has
112 STARTUP, BUCCI, LANGDON
led to significant advances in the theoretical understanding of other
psychotic symptoms such as persecutory delusions (Freeman, 2007),
auditory hallucinations (David, 2004) and passivity experiences (Blakemore,
2003). Until recently, to the authors’ knowledge, only Frith (1992) had
developed an explicit theory about the cognitive processes involved
specifically in delusions of reference. In what follows, we first outline Frith’stheory and summarise its supporting evidence; we also identify what we
consider to be two important shortcomings of the theory. The rest of the
paper then focuses exclusively on referential delusions of communication.
First, we outline a new model designed to account for these delusions. Then
we review three relevant preexisting theories of psychotic states which,
although not developed specifically to account for referential delusions of
communication, appear nevertheless relevant to some aspects of our model.
We then posit a conceptual link between referential delusions of commu-nication and auditory verbal hallucinations in order to justify aspects of our
model. Along the way we present preliminary evidence in support of aspects
of our model.
FRITH’S ‘‘THEORY OF MIND’’ MODEL
According to Frith (1992), delusions of reference, together with persecutory
delusions and third-person auditory verbal hallucinations (i.e., voices
conversing), result from a disorder of Theory of Mind (ToM). ToM refers
traditionally to the capacity to represent and to infer the causal mental states
(e.g., the beliefs and intentions) of self and others in order to predict and
explain behaviour. Frith further suggested that ToM abilities developnormally in childhood in people with schizophrenia, unlike in autistic
spectrum disorders, but become impaired, to varying degrees, later in life
with the onset of the illness and during acute psychotic states. Thus, whereas
autistic people might be considered ‘‘mind-blind’’, people with schizophre-
nia with ToM impairment, in particular those with referential and
persecutory delusions, are better conceived of as ‘‘inaccurate mind-readers’’
(Langdon, 2005; see also Abu-Akel, 1999; Abu-Akel & Bailey, 2000;
Langdon & Brock, 2008, for related discussions); they inaccurately attributeintentions and beliefs to others.
The evidence is now unequivocal that people with schizophrenia show
ToM deficits that cannot be completely accounted for by impairments of
executive functioning, general cognitive impairments or general psycho-
pathology (Harrington, Siegert, & McClure, 2005). However, the evidence
supporting the theory that ToM deficits can explain persecutory and
referential delusions specifically might, at best, be considered inconsistent
DELUSIONS OF REFERENCE 113
(Abdel-Hamid et al., 2009; Harrington et al., 2005; Shryane et al., 2008;
Sprong, Schothorst, Vos, Hox, & van Engeland, 2007).
Despite the qualified empirical support for Frith’s theory, we believe his
model is limited with regard to the understanding of referential delusions
which it can offer. This is so for two main reasons. The first is that Frith’s
(1992) theory provides no account of one of the major defining features ofdelusions of reference, that is that they are self-referential. People with
delusions of reference may be poor at inferring the mental states of others
but, in order to explain the mistaken self-referential inferences they make,
more is required in the theory than deficits in the ability to use available
information to make appropriate inferences of the mental states of others.
The second concern is that Frith’s theory posits a common mechanism
underpinning referential and persecutory delusions, along with voices
conversing, and there are now reasons to think that any commonalitybetween referential and persecutory delusions, and voices conversing, applies
only to referential delusions of observation, not delusions of communication
(Startup & Startup, 2005; see earlier).
A NEW MODEL OF REFERENTIAL DELUSIONSOF COMMUNICATION
In what follows we focus exclusively on delusions of communication (for
brevity, we omit the term referential from now on). We present a new model
in Figure 1 to explain these delusions. This model is designed to account for
what appear to be four crucial aspects of the phenomenology of delusions of
communication: (1) that neutral stimuli are experienced as having personalsignificance; (2) that the neutral stimuli are experienced as communicating a
message nonverbally (or if the stimuli involve language, that the message is
communicated paralinguistically, that is, not by the surface meaning of the
words); (3) that the message concerns the self, that is, it is either addressed to
the self or is about the self; and (4) that the reality of the self-referent
communication is believed rather than being dismissed as implausible.
It will be apparent from our figure that we are adopting a two-factor (or
possibly multifactor) theory of the formation of delusions. In common withother two- (or more) factor theories (Coltheart, Langdon, & McKay, 2007;
Garety, Kuipers, Fowler, Freeman, & Bebbington, 2001; Langdon &
Coltheart, 2000), we attribute a crucial role to anomalous experiences
stemming from basic cognitive impairment(s). However, we also agree that
such cognitive disturbance is insufficient to explain the adoption of a
delusion. We share the view that a second factor, something beyond the first-
factor cognitive disturbance (which causes the anomalous experience), must
also be present to explain the delusional patient’s inability to reject the
114 STARTUP, BUCCI, LANGDON
implausible thought that is triggered by the anomalous experience (e.g., that
God is speaking to me when I hear voices).
The relevance here to our new theory of delusions of communication is
that, according to the two-factor approach, the nature of the (first-factor)cognitive disturbance explains the specific content of the delusion, whereas
the second factor accounts for its adoption and persistence (Langdon &
Coltheart, 2000). For example, the specific content of a passivity delusion is
explained by the loss of the sense of self-generation associated with initiating
one’s own movements, leading to an aberrant experience of ‘‘alien control’’
1. Neutral stimuli from the environmentinappropriately attract attention as of
being significant (salient).
2. Preconscious search for meaning ofperceived salience leads to over-activation of the nonverbal affect
lexicon.
3. Salience interpreted preconsciously asdetection of a (nonspecific) self-referent
nonverbal communicative signal.
4. Preconscious interpretative processesto decode message being signalled:
Activation of (a) decontextualisedmemories of previous nonverbalcommunications, and/or (b) self-
schemas
5. Aberrant conscious experience ofreceiving a content-specific
communication via nonverbal (orparalinguistic) channels
6. Belief-evaluationprocesses, e.g.,
capacity to reject animplausible thought
Impaired:Referential delusionof communication
adopted
Intact:Simple idea of reference,
quickly dismissed asimplausible
7. Autobiographicalmemory and self-schemas updated
Figure 1. A model of the formation of referential delusions of communication.
DELUSIONS OF REFERENCE 115
(Blakemore, 2003). In a similar vein, we postulate that the specific content of
a delusion of communication can be explained by identifying the particular
cognitive disturbance that gives rise to an abnormal referential experience of
communication.
In what follows, we overview the published research that appears to
provide some support for the various steps in our model, or at least to have abearing on them. Much of this research was not explicitly intended to
provide an account of delusions of reference but we believe, nevertheless,
that the relevance to our model is obvious. The amount of research that was
designed specifically to test aspects of this model is, admittedly, small. Thus,
we offer this model, rather boldly, with the desire to stimulate future research
as much as to summarise existing research.
STEP 1: NEUTRAL STIMULI INAPPROPRIATELY ATTRACTATTENTION AS SALIENT
Three notable preexisting theories have a possible bearing on this first step.
First, Hemsley (1987) argued that schizophrenia in general is characterisedby the ‘‘weakening of the influence of stored memories of regularities of
previous input on current perception’’ (p. 55). Furthermore, because of the
lack of influence of stored representations of past regularities of experience,
patients become aware of aspects of the environment that would not normally
reach awareness. This then triggers a search for meaning of the abnormal
experience of ‘‘significance’’ attached to some normally mundane event
(Hemsley, 1993). The relevance to our model is obvious. However, Hemsley’s
theory does not fully explain why personal significance is ascribed to thesemundane events which capture attention. Events can appear significant
without that significance necessarily entailing reference to the self.
In a somewhat similar vein, Corlett et al. (2006) have advanced a theory
which centres on inappropriate prediction error signalling. Prediction error
signalling refers to the signalling of a mismatch between an expected and an
actual input, which diverts attention to unexpected events and stimulates
associations between those events and other concurrent, but possibly
irrelevant, stimuli. Corlett et al. reasoned that inappropriate predictionerror signalling would lead to perceptual aberrations, especially sensations of
the environment being unusually bright, clear, or salient, and that these
sensations in turn would lead to ideas of reference. They tested this model
using functional magnetic resonance imaging of participants who were
administered ketamine prior to performing an associative learning task
designed to induce prediction errors. Among their most important findings
were that ketamine disrupts error-dependent learning activity in the right
frontal cortex and that participants who showed the most frontal activation
116 STARTUP, BUCCI, LANGDON
following a placebo developed the strongest perceptual aberrations and ideas
of reference following the administration of ketamine. Following adminis-
tration of a high dose of ketamine, levels of perceptual aberrations also
correlated highly (r�.7) with ideas of reference. However, in common with
Hemsley, these authors do not provide a clear explanation of why the ideas
that come to mind in reaction to the inappropriate prediction errorsignalling are self-referential.
Another account of psychosis which has some similarities to both of these
theories has been developed by Kapur (2003), who aimed to unite biological,
phenomenological, and pharmacological approaches to explain psychotic
symptoms in schizophrenia. He, like Gray, Feldon, Rawlins, Hemsley, and
Smith (1991), who mapped out the neurophysiological pathways involved in
Hemsley’s model, focused specifically on the role of dopamine, the synthesis
of which is known to be elevated among people who are experiencing apsychotic episode. Dopamine appears to be involved in detecting rewards in
the environment, enhancing understanding about rewards and their
associations, and identifying events as salient in order to stimulate and
maintain goal-directed behaviour (Kapur, Mizrahi, & Li, 2005). Thus,
Kapur proposed that dysregulated dopamine transmission results in
‘‘aberrant assignment of salience to external objects and internal representa-
tions’’ (p. 15) where information, which ought normally to be interpreted as
neutral, captures one’s attention. The search for the meaning of suchaberrant salience subsequently results in delusional beliefs.
Kapur, like Hemsley, did not explicitly intend to provide an account of
delusions of reference but his theory is readily applied to such delusions and,
furthermore, since dopamine is related to the experience of pleasurable and
aversive events for the self, his theory more readily accounts for the self-
referential nature of delusions of reference.
STEP 2: ACTIVATION OF THE NONVERBAL LEXICON
In conceiving of the specific types of cognitive disturbance which might give
rise to a referential experience of communication we offer a new conception
which takes as its starting point a conceptual link between delusions ofcommunication and auditory verbal hallucinations (the aberrant ‘‘referen-
tial’’ experience of hearing voices communicating to or about oneself).
Delusions of communication, we suggest, are similar to delusions concern-
ing voice-hearing in that both begin with an anomalous percept-like
experience of receiving a communication, a message. Startup and Startup
(2005) argued that it is the communicative nature of the referential
experiences of communication that naturally explains the self-referential
DELUSIONS OF REFERENCE 117
content of the delusion: that is, the message is experienced as being sent to
oneself. They also proposed that the main difference between auditory
verbal hallucinations and delusions of communication is that the commu-
nicative channel is spoken words in the former, while the latter centres on
nonverbal channels of communication (including paralinguistic vocal
content and nonvocal gestures and signs). For example, a stranger’sincidental movements might be experienced as a gesture that is intended
to communicate particular content to oneself (e.g., ‘‘I know you are a closet
homosexual’’).
As to why one patient should experience aberrant communicative content
via spoken verbal channels (i.e., the auditory verbal hallucinator) whereas
another patient experiences self-referential communication via nonverbal
channels (i.e., the patient with delusions of communication), there is
neuropsychological evidence to suggest specialised neural systems forprocessing these different types (verbal vs. nonverbal) of communicative
sign. For example, the right hemisphere (among right-handed people)
appears to be more specialised for processing a ‘‘vocabulary’’ of nonverbal
affective signals (e.g., facial expressions, prosody, and gestures), which has
been referred to as the nonverbal affect lexicon, and is conceived as relatively
modular (Bowers, Bauer, & Heilman, 1993). That is, the nonverbal lexicon
might be selectively disrupted (e.g., underconstrained by context or more
easily activated) in some individuals without any concurrent damage to thereception, production, and recall of linguistically decodable messages. Of
course, it is well known that the left hemisphere is (normally) specialised
for the latter type of processing. Thus, we are proposing that delusions
of communication are more likely to occur in those individuals whose
nonverbal affective lexicon is deregulated or easily activated.
STEP 3: DETECTION OF A NONVERBAL COMMUNICATION
To summarise the argument so far, we propose a new model of delusions
of communication, in which the specific content of these delusions can
be explained by postulating both a connection and a disconnection between
the abnormal percept-like referential experiences of communicationwhich seed these delusions and the abnormal false percepts which are
experienced by auditory verbal hallucinators. Both aberrant experiences
centre on the receiving of communications. What differs is the channel of
communication*nonverbal in the case of delusions of communication (for
which the right hemisphere is more specialised) and verbal in the case of
auditory verbal hallucinations (for which the left hemisphere is more
specialised).
118 STARTUP, BUCCI, LANGDON
Some preliminary empirical support for this aspect of our model comes
from a study by Bucci, Startup, Wynn, Heathcote, et al. (2008), which was
based on the signal detection study of auditory verbal hallucinations
conducted by Bentall and Slade (1985). Bentall and Slade showed that,
compared with controls, people with auditory hallucinations, and those
prone to hallucinations, were more biased to report hearing a voiceembedded in white noise when no voice was actually present (though they
were no less perceptually sensitive than the control participants). They
suggested that this bias occurred because the people with a disposition to
auditory verbal hallucinations misattributed self-generated communicative
content (i.e., the self-generated sense of receiving a message with varying
content) to an external source as the origin of that communicative content.
Thus, it was suggested that auditory verbal hallucinations reflect a ‘‘reality
discrimination error’’. We use the term ‘‘reality discrimination error’’ verygenerally here to refer to a mistaken attribution to an external source of
some content which is largely self-generated internally.
Bucci and colleagues adapted the Bentall and Slade paradigm to test the
theory that a cognitive disturbance, somewhat similar to that seen in
auditory verbal hallucinators, is also present in people with referential
delusions of communication. Since the people with delusions of commu-
nication purportedly ‘‘hallucinate’’ a nonverbal communicated message,
whereas the auditory hallucinators hear a verbal message, Bucci andcolleagues presented participants with video clips of an actor who, in
different clips, either used a widely recognised nonverbal gesture (e.g.,
beckoning) or else made an incidental movement of the same duration that
would not normally be construed as intending to communicate any meaning
to others (e.g., moving hair away from eyes). All of the clips were obscured
with visual noise (‘‘snow’’). The participants’ task following each clip was to
decide if a meaningful gesture or an incidental movement had been shown.
The results showed that people with versus without delusions of commu-nication had a more liberal bias towards reporting meaningful gestures as
being present. The main effect for presence versus absence of auditory verbal
hallucinations was nonsignificant.
Of course, these results show only that people with delusions of
communication were more willing to indicate that meaningful gestures had
been shown. However, one possible interpretation of the results, in line with
Bentall and Slade, is that the people with delusions of communication were
more biased to report gestures because they misperceived meaningfulgestures as being present in the absence of appropriate sensory information
that would justify the ‘‘gesture-perception’’ and that this occurred because
they misattributed meaningful communicative content, which was primarily
self-generated, to an external communicative source.
DELUSIONS OF REFERENCE 119
STEP 4: SEARCH TO DECODE THE MESSAGE
So, thus far, we have argued that neutral stimuli, which are inappropriately
assigned salience, activate the nonverbal lexicon in a preconscious search for
meaning. It is this activation which explains the detection of a nonverbal
communicative signal. However, while the study by Bucci, Startup, Wynn,
Heathcote, et al. (2008) suggested that people with delusions of commu-
nication are biased to misperceive neutral social events as having commu-nicative intent, it did not show that such people experience such apparent
communications as self-referential. Some suggestive evidence that this is so
has recently been presented by Bucci, Startup, Wynn, Baker, and Lewin
(2008) in their study of the interpretations that acutely psychotic people
place upon neutral social events.
In this study, video clips of gestures and incidental movements were
presented (without being obscured by visual noise), following each of
which participants selected one of four interpretations presented in randomorder: a ‘‘correct’’ interpretation if a gesture had been presented; another
gesture from the pool of gestures (incorrect); a rejecting or insulting
interpretation of the movement (always incorrect); and no gesture intended
(‘‘correct’’ interpretation if an incidental movement had been presented).
Although most of the interpretations selected by the patients were correct,
they misinterpreted significantly more of the nonmeaningful incidental
movements as gestures, compared with a control group, and selected
significantly more insulting interpretations of the clips even though all themovements in the clips were affectively neutral in content and the actor
maintained a neutral expression. What is most remarkable, however, was
that the differences between patients and controls were almost wholly due to
patients with delusions of communication; patients without delusions of
communication made hardly any more errors than the control participants.
One possible interpretation of the last of these findings is that the
misperceived communicative content (conveyed via nonverbal channels of
communication) often derives from the patient’s own self-critical beliefs (i.e.,their negative self-schemas) which then feed into the online processing of the
incoming gesture information in a top-down way.
In order to gain further insights concerning the origin of the meaningful
content that ‘‘fills in’’ the message conveyed by the nonverbal communicative
signal misperceived by people with delusions of communication, we now
consider one current theory of auditory verbal hallucinations that might be
relevant.
Waters, Badcock, Michie, and Maybery (2006) have suggested thatauditory verbal hallucinations derive from the unintentional activation of
auditory verbal memories, and other irrelevant current mental associations,
which are not recognised as originating as such because of deficits in
120 STARTUP, BUCCI, LANGDON
contextual or source memory. According to this theory, two cognitive
deficits combine to explain auditory verbal hallucinations1: deficient
inhibition of irrelevant memories and defective contextual binding. Support
for this theory comes first from a study which showed that people with
auditory verbal hallucinations had difficulty in suppressing memories of
prior events that were not relevant to the online reality (Badcock, Waters,Maybery, & Michie, 2005). More recently, Waters et al. found that almost
90% of people currently experiencing auditory verbal hallucinations had the
combination of deficits in both inhibition and context memory (compared
with only 33% of patients without such hallucinations), and that the people
with both kinds of deficit were about six times more likely to have auditory
hallucinations than the people without both deficits.
It seems possible that similar inhibitory and context-processing deficits
might also contribute to delusions of communication in that the intrusion ofirrelevant, poorly sourced memories, due to poor intentional inhibition,
might nuance the preconscious top-down ‘‘filling in’’ of the message
conveyed, in this case via nonverbal rather than spoken-verbal channels of
communication. Such memories will also likely contain the self-critical
information highlighted above when reviewing the Bucci, Startup, Wynn,
Baker, & Lewin (2008) findings concerning a negative bias in the
interpretation of gestures misperceived as meaningful.
To summarise this section, we propose that decontextualised memories ofhaving received nonverbal messages with particular content in the past, as
well as negative self-schemas, contribute to the ‘‘filling in’’ of the commu-
nicative signal with a typically negative, self-referential message.
STEPS 5 AND 6: BELIEF FORMATION
At the end of the processes outlined in the first four steps, the individual has a
conscious sense of having received a communication with specific content via
nonverbal (or paralinguistic) channels. The content of this communication
will be experienced quite naturally as self-referential since the content is that
of a message sent to the self from an external source, and the content might
also have been elaborated by preconscious intrusions from an insufficientlyinhibited and poorly sourced autobiographical memory. Aberrant referential
experiences of communication of this type might then lead only to simple
ideas of reference, which come to mind but which are quickly dismissed as
1 We note here that the Waters et al. model encompasses more than auditory hallucinations;
however, our focus here is on understanding the specific communicative content of referential
delusions of communication and so we refer specifically to the Waters et al. conception of auditory
verbal hallucinations.
DELUSIONS OF REFERENCE 121
implausible. If, however, the individual has further (second-factor) impair-
ment, which affects normal belief evaluation processes, then the implausible
referential idea may be accepted uncritically as true and a delusion of
communication will be adopted. This initial delusion may or may not
then lead on to other delusions and the elaboration of a related delusional
system. Current evidence suggests that there may be several contributorsto a delusion-prone cognitive style of this type, including: a jumping-to-
conclusions style of data gathering, belief inflexibility, tendencies to extreme
responding (Garety et al., 2005), an impaired capacity to inhibit a prepotent
tendency to upload and maintain experiential content into belief (Langdon,
Ward, & Coltheart, in press), and a bias against disconfirmatory evidence
(Woodward, Buchy, Moritz, & Liotti, 2007).
STEP 7: MEMORIES OF PREVIOUS SIMILARCOMMUNICATIONS
With regard to contents that individuals misperceive as having been
communicated via nonverbal channels, we would acknowledge that therichness of the message may vary considerably. One ‘‘receiver’’ may only
sense the presence of a communicative signal conveyed, for example, via a
gesture or an impersonal sign in the environment (e.g., a street sign) and
must then search for the meaning, whereas another receiver may experience
being directly ‘‘told’’ via the nonverbal sign that, for example, he/she is a
closet homosexual. This variation in the depth of content may reflect both
the varying involvement of preconscious processing of associations prior
to the initial conscious percept (see, e.g., Frith, 1979, in relation to explainingthe variable content of auditory verbal hallucinations) and the duration of
the referential delusional beliefs. With regard to the latter, Young (2008) has
proposed an interactionist model of delusions in which he suggests that, with
time, the delusional belief feeds back into the patient’s online preconscious
processing of incoming aberrant conscious experience. In relation to
delusions of communication, the idea here is that individuals move from
initially perceiving a relatively content-free nonverbal communicative signal
which they consciously interpret, at the time, as a message of disdain abouttheir hidden homosexual tendencies, to later experiencing the direct receipt
of a message of criticism about being a closet homosexual being conveyed
via a nonverbal communicative sign.
SUMMARY
Putting the foregoing together, we propose the following integration. At
the neurotransmitter level, dopamine dysregulation results in aberrant
122 STARTUP, BUCCI, LANGDON
assignment of salience to mundane environmental events (Kapur, 2003), or
abnormal glutamate firing in the prefrontal cortex causes inappropriate
prediction error signalling (Corlett et al., 2006; see also Hemsley’s, 1987,
suggestion of a failure of past regularities of experience to influence current
processing of sensory inputs). These accounts may not be in conflict with one
another but may be overlapping or complementary theories; Corlett et al.,2006). The aberrant signals of salience/significance which are triggered in
people with referential ideas or delusions of communication preferentially
activate right hemisphere networks which are dedicated to the processing of
nonverbal signals of communication (including paralinguistic vocal cues
and nonvocal gestures and signs). Memories and/or schemas, which are
‘‘primed’’, either because prior conscious processing to interpret the signals
has become automatic or because unconscious motivational factors are at
work, become activated in the preconscious interpretative processing of themeanings of the signals. The person fails to source the interpreted meaning
that comes to consciousness as being largely internally generated (perhaps
exacerbated by concurrent inhibitory deficits) and ‘‘misperceives’’ the receiv-
ing of a communication via nonverbal channels. The misperception is then
either dismissed as implausible or believed with conviction, depending on the
presence or absence of normal belief evaluation processes, which might be
disrupted in varying ways in delusion-prone individuals.
FUTURE RESEARCH
Much of the support for our model that we have put forward is suggestive or
speculative rather than confirmatory. Clearly more research is needed to testthe model thoroughly. Space does not permit us to describe all the research
we believe is needed but here we outline three areas. First, a central idea is
that delusions of communication are initiated when aberrantly salient events
differentially activate the nonverbal affect lexicon which resides in the right
hemisphere. This hypothesis might be testable with functional magnetic
resonance imaging if it should prove possible to reliably induce erroneous
perceptions of nonverbal communication in people with delusions of
communication, say using videos of incidental movements interspersedwith videos of genuine gestures. Second, we have suggested that delusions of
communication occur when memories of previous nonverbal communica-
tions are activated but are not recognised as such because of deficits in
context memory. Inhibitory impairments might also feature here via a failure
to suppress such memories. Adaptations of paradigms developed by
Badcock et al. (2005) to test source monitoring and inhibition deficits in
people with auditory verbal hallucinations might be useful to test these
ideas. Lastly, in order to explore the self-referential nature of delusions of
DELUSIONS OF REFERENCE 123
communication, one might investigate the influence of the patients’ own
previous experiences and self-critical thoughts on the misperceived commu-
nicative content, say using an adaptation of the Bucci, Startup, Wynn,
Baker, and Lewin (2008) methodology.
No doubt other researchers will consider different kinds of evidence to be
crucial to our model. If this paper stimulates them to put aspects of themodel to the test, then it will have served its purpose.
Manuscript received 7 May 2008
Revised manuscript received 4 March 2009
REFERENCES
Abdel-Hamid, M., Lehmkamper, C., Sonntag, C., Juckel, G., Daum, I., & Brune, M. (2009).
Theory of mind in schizophrenia: The role of clinical symptomatology and neurocognition in
understanding other people’s thoughts and intentions. Psychiatry Research, 165, 19�26.
Abu-Akel, A. (1999). Impaired theory of mind in schizophrenia. Pragmatics and Cognition, 7,
247�282.
Abu-Akel, A., & Bailey, A. L. (2000). Letter to the editor. Psychological Medicine, 30, 735�738.
Badcock, J. C., Waters, F. A., Maybery, M. T., & Michie, P. T. (2005). Auditory hallucinations:
Failure to inhibit irrelevant memories. Cognitive Neuropsychiatry, 10, 125�136.
Bentall, R. P., & Slade, P. D. (1985). Reality testing and auditory hallucinations: A signal detection
analysis. British Journal of Clinical Psychology, 24, 159�169.
Blakemore, S.-J. (2003). Deluding the motor system. Consciousness and Cognition, 12, 647�655.
Bowers, D., Bauer, R. M., & Heilman, K. M. (1993). The nonverbal affect lexicon: Theoretical
perspectives from neuropsychological studies of affect perception. Neuropsychology, 7, 433�444.
Boydell, J., Dean, K., Dutta, R., Giouroukou, E., Fearson, P., & Murray, R. (2007). A comparison
of symptoms and family history in schizophrenia with and without prior cannabis use:
Implications for the concept of cannabis psychosis. Schizophrenia Research, 93, 203�210.
Bucci, S., Startup, M., Wynn, P., Baker, A., & Lewin, T. J. (2008). Referential delusions of
communication and interpretations of gestures. Psychiatry Research, 158, 27�34.
Bucci, S., Startup, M., Wynn, P., Heathcote, A., Baker, A., & Lewin, T. J. (2008). Referential
delusions of communication and reality discrimination deficits in psychosis. British Journal of
Clinical Psychology, 47, 323�334.
Coltheart, M., Langdon, R., & McKay, R. (2007). Schizophrenia and monothematic delusions.
Schizophrenia Bulletin, 33, 642�647.
Corlett, P. R., Honey, G. D., Aitken, M. R. F., Dickinson, A., Shanks, D. R., Absalom, A. R., et al.
(2006). Frontal responses during learning predict vulnerability to the psychotogenic effects of
ketamine: Linking cognition, brain activity, and psychosis. Archives of General Psychiatry, 63,
611�621.
David, A. S. (2004). The cognitive neuropsychiatry of auditory verbal hallucinations: An overview.
Cognitive Neuropsychiatry, 9, 107�123.
Freeman, D. (2007). Suspicious minds: The psychology of persecutory delusions. Clinical
Psychology Review, 27, 425�457.
Freeman, D., Garety, P. A., Bebbington, P. E., Smith, B., Rollinson, R., Fowler, D., et al. (2005).
Psychological investigation of the structure of paranoia in a non-clinical population. British
Journal of Psychiatry, 186, 427�435.
124 STARTUP, BUCCI, LANGDON
Frith, C. D. (1979). Consciousness, information processing and schizophrenia. British Journal of
Psychiatry, 134, 225�235.
Frith, C. D. (1992). The cognitive neuropsychology of schizophrenia. Hove, UK: Lawrence Erlbaum
Associates Ltd.
Garety, P. A., Freeman, D., Jolley, S., Dunn, G., Bebbington, P. E., Fowler, D. G., et al. (2005).
Reasoning, emotions, and delusional conviction in psychosis. Journal of Abnormal Psychology,
114, 373�384.
Garety, P. A., Kuipers, E., Fowler, D., Freeman, D., & Bebbington, P. E. (2001). A cognitive model
of the positive symptoms of psychosis. Psychological Medicine, 31, 189�195.
Gelder, M., Gath, D., & Mayou, R. (1989). Oxford textbook of psychiatry (2nd ed.). Oxford, UK:
Oxford University Press.
Gray, J. A., Feldon, J., Rawlins, J. N. P., Hemsley, D. R., & Smith, A. D. (1991). The
neuropsychology of schizophrenia. Behavioral and Brain Sciences, 14, 1�19.
Harrington, L., Siegert, R. J., & McClure, J. (2005). Theory of mind in schizophrenia: A critical
review. Cognitive Neuropsychiatry, 10, 249�286.
Hemsley, D. R. (1987). An experimental psychological model for schizophrenia. Heidelberg,
Germany: Springer.
Hemsley, D. R. (1993). A simple (or simplistic?) cognitive model for schizophrenia. Behaviour
Research and Therapy, 31, 633�646.
Kapur, S. (2003). Psychosis as a state of aberrant salience: A framework linking biology,
phenomenology, and pharmacology in schizophrenia. American Journal of Psychiatry, 160,
13�23.
Kapur, S., Mizrahi, R., & Li, M. (2005). From dopamine to salience to psychosis*linking biology,
pharmacology and phenomenology of psychosis. Schizophrenia Research, 79, 59�68.
Langdon, R. (2005). Theory of mind in schizophrenia. In B. F. Malle & S. D. Hodges (Eds.), Other
minds: How humans bridge the divide between self and others (pp. 333�342). New York: Guilford
Press.
Langdon, R., & Brock, J. (2008). Hypo- or hyper-mentalizing? It all depends upon what one means
by ‘‘mentalizing’’. Behavioral and Brain Sciences, 31, 274�275.
Langdon, R., & Coltheart, M. (2000). The cognitive neuropsychology of delusions. Mind and
Language, 15, 184�218.
Langdon, R., Coltheart, M., & Ward, P. B. (in press). Reasoning anomalies associated with
delusions in schizophrenia. Schizophrenia Bulletin. Advance online publication. Retrieved
July 11, 2008; doi:10.1093/schbul/sbn069.
Leon, C. A., Bowden, C., & Faber, R. (1989). Diagnosis and psychiatry: Examination of the
psychiatric patient. In H. I. Kaplan & B. J. Sadock (Eds.), Comprehensive textbook of psychiatry
(5th ed., pp. 449�462). Baltimore: Williams & Wilkins.
Minas, I. H., Stuart, G. W., Klimidis, S., Jackson, H. J., Singh, B. S., & Copolov, D. L. (1992).
Positive and negative symptoms in the psychoses: Multidimensional scaling of SAPS and
SANS items. Schizophrenia Research, 8, 143�156.
Phillips, K. A., McElroy, S. L., Keck, P. E., Pope, H. G., & Hudson, J. I. (1993). Body dysmorphic
disorder: 30 cases of imagined ugliness. American Journal of Psychiatry, 150, 302�308.
Poulton, R., Caspi, A., Moffit, T. E., Cannon, M., Murray, R., & Harrington, H. (2000). Children’s
self-reported psychotic symptoms and adult schizophreniform disorder: A 15-year longitudinal
study. Archives of General Psychiatry, 57, 1053�1058.
Shryane, N. M., Corcoran, R., Rowse, G., Moore, R., Cummins, S., Blackwood, N., et al. (2008).
Deception and false belief in paranoia: Modelling theory of mind stories. Cognitive
Neuropsychiatry, 13, 8�32.
Sprong, M., Schothorst, P., Vos, E., Hox, J., & van Engeland, H. (2007). Theory of mind in
schizophrenia: Meta-analysis. British Journal of Psychiatry, 191, 5�13.
DELUSIONS OF REFERENCE 125
Startup, M., & Startup, S. (2005). On two kinds of delusion of reference. Psychiatry Research, 137,
87�92.
Waters, F. A., Badcock, J. C., Michie, P. T., & Maybery, M. T. (2006). Auditory hallucinations
in schizophrenia: Intrusive thoughts and forgotten memories. Cognitive Neuropsychiatry, 11,
65�83.
Wing, J. K., Cooper, J. E., & Sartorius, N. (1974). Measurement and classification of psychiatric
symptoms (9th ed). Cambridge, UK: Cambridge University Press.
Woodward, T. S., Buchy, L., Moritz, S., & Liotti, M. (2007). A bias against disconfirmatory
evidence is associated with delusion proneness in a nonclinical sample. Schizophrenia Bulletin,
33, 1023�1028.
World Health Organization. (1973). Report of the International Pilot Study of Schizophrenia
(Vol. 1). Geneva: Author.
Young, G. (2008). Capgras delusion: An interactionist model. Consciousness and Cognition, 17,
863�876.
126 STARTUP, BUCCI, LANGDON