schizophrenia - individual differences

• cognitive approach - explaining hallucinations

  even though hallucinations are experienced by many with schizophrenia, it is estimated that between 2.5% and 4% of the general population have experienced hallucinations, most of whom are not diagnosed with a psychiatric problem (Claiborn 2009)
• explaining hallucinations


  Anthony Morrison (1998) proposed that triggers, such as sleep deprivation, can cause some individuals to 'hear' voices in maladaptive ways. The individuals appraise these voices inappropriately as belonging to the devil, for example. This elicits behaviours such as social withdrawal or self-harm. The emotions that these behaviours produce, normally sadness and/or shame, reinforce the messages being offered by the critical voices, causing them to be perpetuated in a vicious circle.
• explaining negative symptoms


  the cognitive approach has traditionally had more difficulty explaining the negative symptoms of schizophrenia than, for example, hallucinations. Aaron Beck et al (2008) have drawn heavily from the idea of the cognitive triad, usually used to explain depression, to also offer a reasonable model of the negative symptoms seen in some individuals with schizophrenia.
• explaining negative symptoms


  Beck et al propose that the individual endorses dysfunctional beliefs about their performance and their ability to experience pleasure, they also hold a cynical and gloomy view of the future. Their mental filters only allow in negative messages and deficits in information processing bolster their pessimistic view. These leads to the negative symptoms of schizophrenia such as flat affect, avolition and anhedonia
• Preconscious filters


  Attentional filters that normally inhibit most sensory information from making it out of the preconscious
• Lack of preconscious filters
• Proposed explanation for positive symptoms of schizophrenia

  • Difficulties in inhibiting preconscious content
  • Individuals become aware of ambiguous and multiple interpretations of events
  • Individuals find it difficult to select and carry through an appropriate course of action
• Christopher Frith (1979): 'The core positive symptoms of schizophrenia could be explained by difficulties in inhibiting preconscious content'
• Normally, our senses receive a tremendous amount of information from our environment, this information reaches our awareness and we interpret it
• The 'best fit' of the incoming information gets propelled into our consciousness, allowing us to make sense of the information
• In some people the attentional filters that inhibit most of the sensory information from making it out of the preconscious are defective
• compromised theory of mind


  more recently, Frith (1992) proposed that individuals with schizophrenia are working with a compromised theory of one's own and others' minds. He believes that many of the symptoms seen in those with schizophrenia are the result of disorders within three separate cognitive systems
• compromised theory of mind - three separate cognitive systems:
• the three separate systems (compromised theory of mind)

  the disorders of willed action (voluntary behaviour) can explain negative and disorganised symptoms of schizophrenia

  disorders of self-monitoring can explain symptoms such as delusions of alien control and vocal hallucinations

  disorders of monitoring other persons' thoughts and intentions, csn lead to symptoms such as delusions of persecution
• The cognitive models and theories proposed by researchers like Beck and Frith have led to a tremendous amount of scientific research being conducted
• Deanna Barch et al (1999)


  • Compared performance on a Stroop test of people with schizophrenia and people without it
  • Found those with schizophrenia were slower and made more mistakes on the Stroop test
  • Concluded that this was evidence that those with schizophrenia couldn't filter the information as effectively, supporting Frith's idea that the attentional filters of individuals with schizophrenia are defective
• Cognitive models and theories proposed by researchers


  Led to a tremendous amount of scientific research being conducted
• Reductionist account


  Explanation that reduces a complex experience to the functioning of brain circuits
• Frith's explanation for deficits associated with schizophrenia

  Faulty operation of cognitive mechanisms due to disconnection between frontal cortex (decision making and action) and posterior areas of the brain (perception)
• Frith has produced supportive evidence by detecting changes in cerebral blood flow in the brains of people with schizophrenia when contemplating cognitive tasks
• Some critics suggest that Frith is being reductionist because his explanation reduces a complex experience to the functioning of brain circuits
• not a comprehensive theory

  some researchers criticise the cognitive explanations as only being able to explain cognitive symptoms of schizophrenia. Other symptoms, such as issues with movement are not explained well by cognitive explanations.In addition, cognitive explanations are criticised for only describing the cognitive deficits thought to underlie symptoms of schizophrenia, but no not always explain the origin of these deficits. This suggests that we should perhaps be cautious about the claims made by the cognitive approach as a single explanation for the disorder of schizophrenia.
• Integrated model of schizophrenia


  Proposes that genes or certain factors early in life (e.g. birth complications) combine with life events of social stressors (e.g. poverty) and this provokes the dopamine system into releasing dopamine
• Increase in dopamine secretion

  Causes problems with cognitive processing, specifically delusions and hallucinations
• Individual with schizophrenia experiences symptoms

  Prompts the release of more dopamine
• The cognitive explanation alone is insufficient but it can contribute to a wider theory
• Psychologists are now starting to appreciate that schizophrenia needs to be considered in a more holistic way - which can include cognitive factors