Delusions and Paranoia

  • Created by: NATASHAOX
  • Created on: 12-12-18 19:01

Defining delusions

- BIZARRE or UNUSUAL beliefs. 

-How can you define what classifies a certain belief as delusional? 


Argued that the abnormal beliefs of patients are bizarre, resistant to counter-argument and held with extrodinary conviction. However true delusions are also un-understanble 

They cannot be understood in terms of 

1. The patients personality 

2. The patients experiences 

Therefore, they can only be explained in terms of abnormal biology 

BERRIOS (1991) 

Delusions are 'empty speech acts whose informational content refers to neither world or self' 

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Form and content


distinguised between form and content of disorders. 

FORM= How the symptom emerges 

CONTENT= what the delusion actually was 

form= how

content= what 

He belived the WHAT was inconsequential when it came to diagnosis - not important or worth investigating.

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DSM definitions

DSM definitions are more modern (DSM 5)  

Defines a DELUSION as:

'A fale personal belief based on an incorrect inference about external reality that is firmly sustained despite what amost everyone else belives and despite whar constitues incontrovertible and obvious proof or evidence to the contrary. The belief is not one ordinarily accpted by the other members of the persons culture or subculture. 

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How rigid are Delusional Beliefs?


observed a meeting between two inhibitants of a psychiatric hospital one believed he was incorporated with jesus christ and the other who believed he was the enteranl father. 


discovered that three of the patients at the YPH believed that they were christ and arranged for them to live together on a ward. 

- cung to their delusional beleifs 

-the one accepted that these people were christ but he wasnt but he development a new delusion that he was a pschiatrist married to god. 

-all three expressed sympathy towards the other two because they were convinced the other two were mad and that they were sane. 

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How rigid are Delusional Beliefs?


Assesed conviction, preoccupation and interference (tendency to act on delusions) in 9 patients who were interviewed on average 12 times in a 6 month period. 

-fluctuated more for delusional beleifs in comparison to truths e.g the sun will rise tomorrow. 

-There was no correlation between conviction and either preoccupation or interfernce 

correlation between preoccupation and interference was only modest. 

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Types of Delusions

Persecutory Delusions

Paranoid delusions 

-Considered the most COMMON type of delusion 

*42% of danish inpatients and 35% of british deluded patients


compared delusions of patients from europe, carribean, india africa, middle east and the far east. Persecutory delusions most common everywhere BAR the FAR EAST

-vast cultural differences in the content of paranoid delusions have been found. 

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Grandoise Delusions & Delusions of reference


*propsed 4 types

-special powers


-special mission

-special identity 


-The belief that some kind of innocuous event 

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-Includes beliefs that seem to involve the misinterpretation of sensory experinces. 

-probably underestimated in the literature 

McGilchrist and Cutting (1996) found this kind of belief in 55% of 550 patients. - over half. 

e.g delusional parasitosis

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Less common Delusions


ertomania (someone feels they are secrelty loved e.g someone famous)

Delusional jealousy: (loved one irrationally belived to be unfaithful) 


argues that delusional jealousy shows that delusions can be ture- spouses often leave delusionally jealous patients

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Capgras delusion - The belief that a loved one has been replaced by an imposter/doppelganger. 

Delusion of Inanimate doubles- (ANDERSON) in which emotionally significant personal items are believed to have been maliciously replaced by poor copies. 

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A paranoid continium?

taxometric analysis paranoia!

supports the notion that we are all a little bit paranoid 

tick items 20. 

hierarchy of paranoia (from freeman et al) 

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Argue that there are TWO difefrent types of paranoia 

-POOR ME - paranoia (persecution UNdeserved) 

-BAD ME- paranoia (persecution deserved) 

in 2005- reported that self-esteem was higher in PM (undeserved) patients compared to bm patients. The authors self-categorised patients into poor me and bad me. 

-HOWEVER there has been research to examine the distinction. 

PaDs (MELO) 

to more accurately test PM AND BM the persecution and deservedness scale was developed for clinical pop and general pop. 

322 undergrads and 45 acutely psychotic patients! o- certainly false 4-certainly true

if answered two or above to last question answer next. 

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* Adequate reliability was found for both dimensions. In NON patients a clesr relationship was observed between paranoia and deservedness but this relationship was absent in patients

*in the patient sample deservedness scores appered to be low even when they re highly paranoid. 

Fluctuations in deservedness 

ESM study with 14 pm and 15 BM. deservedness measured at each beep. 

found that deservedness scores of people with BM paranoia were actually more unstable/tended to fluctuate more than people with BM paranoia. 

Seems like delusions in general desevredness is unstanble. 

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Psychological Mechanisms

A simple model of belief acquisition 


data-perception and attention-inference-belief 



Bias against disconfirmatory evidence compared to patients without delusions. 

the relevnce of potentially disconfirmatory evidence is downplayed or ignored

bias is reported even for delusion neutral material

BADE is a core feature of delusions in schizophrenia spectrum replicated in several studies. 

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Perceptual deficits

MAHER et al 

Have argued that reasoning is normal in deluded patients- no deficit in reasoning or logic. 

delusions therefore result from the patients attempt to explain anomalous experineces

anomalous experience = any unusual experience that can be iterpreted differently by people

COOPER et al -  reported that paranoia in the elderly was associated with the slow onset of deafness. 

later studies have failed to find an association between deafness and paranoia. 

recent epidemiological studies have found that hearing problems actually predicted the later onset of psychosis. 

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HUQ et al 

participants were shown 2 jars with beads of two colours in ratios of 80:20 and 20:80 a sequence of beads is shown apparently from one of the jarsthey had to guess which jar 

participants with delusions tended to jump to conclusions guessing after fewer draws

although well replicated this effect is not found when participants estimate their confidence about which jar the beads have come from 

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its been argued that paranoid patients have difficulty in understanding other peoples thoughts and feelings. 

assesed by false beleif stories, hinting tasks. 

psychotic patients perform poorly on tom tasks but specificty to paranoia is not proven. 

ToM and JTC bias 


assesed both tom and jtc in their sample of schiz and depressed patients with and without paranoia and healthy cobtrols associated with poor jtc performance and theory of mind. 

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Attributional explanatory style

fundamental observation

paranoid patients make abnormal attributions

Kaney et al - found paranoid patients made excessively stable and global attributions for negative events. showed extreme self serving bias. 

paranoia is associated with cognitive biases in information search, attention, perception and attributes. 

paranoid patients tend to make external and personal attributions for negative events and internal personal attributions for positive events (self-serving bias) 

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psychological models

The original attributional model. 

Bentall et al 

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