Attributional Style in Schizotypy as a Reflection of Paranoia and Grandiosity

Research output: ThesisDoctoral Thesis

2 Downloads (Pure)


Paranoia can be defined as the unrealistic mistrust of other people, and encompasses beliefs about being disliked, criticised, deceived, betrayed, conspired against and harmed by others. Paranoid beliefs that become clinically distressing or disruptive are known as persecutory delusions, and are a common symptom of schizophrenia. Grandiose beliefs, in which one overestimates one’s importance, abilities, and achievements, can also become delusional in schizophrenia.

Some researchers think that an excessive tendency to blame other people for their negative events can protect self-esteem but lead to paranoia. In support of this, studies have shown that patients with persecutory delusions have heightened tendencies (1) to take more responsibility for positive than negative events (the ‘self-serving bias’) and (2) to blame other people, rather than chance or circumstance, for negative events (the ‘personalising bias’). However, it is unclear whether these biases of attributional style are associated with paranoia in the general population.

The thesis addressed this issue in two ways. Firstly, it examined whether existing studies supported a relationship between attributional biases and non-clinical paranoia. Secondly, it presented an original experimental study of whether attributional biases are associated with high levels of schizophrenia-like features (‘schizotypy’) in the general population, and with non-clinical persecutory and grandiose beliefs.

Literature Review
The literature review found that existing studies were generally unable to find a significant association between attributional biases and paranoia in the general population. Problems were noted with the way attributional biases were measured in most studies that did find relationships with non-clinical paranoia. Only one study showed good evidence that non-clinical individuals with a very high level of paranoia have a heightened tendency to blame other people, rather than oneself, for negative events (the ‘other-person blaming bias’).

Existing studies consistently showed that paranoia in the general population is linked with a tendency to interpret other people’s ambiguous actions as being hostile. However, it was argued that this tendency is not a type of attributional bias, despite being referred to as such by some researchers.

Experimental Study
Self-serving, personalising and other-person blaming biases were measured in 80 university students. 38 had high schizotypy and 42 had low schizotypy, and they scored in the top and bottom 15% (respectively) of 369 students who were screened for schizotypy. The groups were similar in age, gender, nationality, cultural background, education and intelligence, but the high schizotypy group had higher depression, anxiety and stress.

The high schizotypy group had a significantly lower (rather than higher) self-serving bias than the low schizotypy group, a difference that became nearly-significant when level of depression was taken into account. There were no significant differences in personalising and other-person blaming biases between the two groups.

Higher personalising bias was significantly related to higher levels of suspiciousness, paranoia, persecutory belief and grandiose belief in the high schizotypy group only. There was mixed evidence that these relationships were related to lower consideration of situational factors in general when making external attributions.

The majority of participants with persecutory beliefs (88%) had co-occurring grandiose beliefs, indicating that persecutory beliefs in the general population tend to be held alongside grandiose beliefs, rather than in isolation. Participants were divided into three groups: 21 ‘dual beliefs’ participants holding both persecutory and grandiose beliefs; 25 participants holding just grandiose beliefs; and 29 participants with neither belief.

The groups were similar for age, gender, nationality, cultural background, education and intelligence. The grandiose belief group and neither belief group had similar levels of depression, anxiety and stress, which were all significantly lower than the dual beliefs group. The dual beliefs group were highest, the neither belief group lowest, and the grandiose belief group intermediate, for levels of schizotypy and paranoia.

Self-serving and other-person blaming biases were heightened in the grandiose belief group compared to the dual beliefs group (significant difference) and the neither belief group (near-significant difference). Personalising bias was near-significantly heightened in the grandiose belief group and significantly heightened in the dual belief group, compared to the neither belief group. Self-serving and other-person blaming biases were not significantly heightened in the dual beliefs group.

The thesis concluded that self-esteem-protecting attributional biases are not related to schizotypy and non-clinical paranoia, and that paranoia is therefore unlikely to develop from a need to protect one’s self-esteem. Whilst there was evidence from the experimental study that personalising bias is related to non-clinical paranoia in high schizotypy, this bias by itself does not appear to have a self-esteem-protecting function. Personalising bias in high paranoia may instead reflect an increased perception of other people as being harmful or powerful, perhaps derived from previous adverse interpersonal experiences.

The present findings tentatively suggest that people with grandiose beliefs have heightened self-esteem-protecting attributional biases, including a heightened tendency to blame other people, rather than oneself, for negative events. These biases may result from the holding of a very positive self-concept, and a very negative concept of other people. It was concluded that grandiosity in the general population may develop from a need to protect or enhance one’s self-esteem, which may then cause attributional biases.

It was suggested that future studies are required to show that co-occurring grandiosity is not responsible for the heightened attributional biases that have been demonstrated in people with persecutory delusions. Greater consideration of alternative possible causes of paranoia, rather than biased attributional style, is advocated for future research and therapeutic treatments. These causes may include the roles played by previous experiences of harm and powerlessness from other people in creating a heightened perception of others as being harmful and powerful.
Original languageEnglish
Awarding Institution
  • Royal Holloway, University of London
  • Rossell, Susan, Supervisor, External person
  • Macleod, Andy, Supervisor, External person
Publication statusPublished - 2023


  • Attributional Style
  • Attributional Bias
  • Schizotypy
  • Paranoia
  • Grandiosity
  • Schizophrenia
  • Psychosis
  • Delusions

Cite this