This blog post will look at what hallucinations are, what causes them, and what can be do to help people who suffer from them. Normally, we are pretty good at identifying what’s real in the environment, but occasionally this processing is distorted, and people see things which aren’t there. This is a hallucination, and the most common type is auditory.


Although they are a symptom of schizophrenia, they can occur in people without the condition, and factors such as drug use, sleep or sensory deprivation or bereavement can make them more likely to occur.

It has been hypothesised that hallucinations are caused by an internal event being misattributed to an external source. For example, internal speech is thought to originate from something external, and so is experienced as hearing a voice. Evidence to support this comes from a study by McGuire et al (1993) who found increased blood flow to Broca’s area during auditory hallucinations – this is an area of the brain involved in language production.

This externalising bias is thought to be caused by impairments in self-monitoring, which means that sufferers do not identify the sense of effort or intention behind their actions. Evidence for this comes from studies such as one carried out by Johns et al (2001), which ask patients to speak words out loud into a microphone. The words are then played back to the individual, some distorted and some in another person’s voice. The patient then has to identify whether or not they spoke the word. This study found that patients with hallucinations were more likely than healthy controls to identify their speech as someone else’s.


One of the most successful ways to treat hallucinations is using cognitive therapy, which involves challenging people’s beliefs about their voices. At first this is done using a hypothetical contradiction, before progressing to directly questioning their beliefs.

A new form of therapy to treat hallucinations has recently been developed, and involves the use of technology. Leff et al (2013) helped patients develop an avatar which resembled the voice their hear, and the patient was encouraged to stand up to the voice. The therapist spoke as the voice, and gradually changed their responses so that the avatar was under the control of the patient. This technique was found to reduce hallucinations more than traditional methods.

However, most of the research has only focused on auditory hallucinations, whereas they can occur in any sensory modality. Therefore, more needs to be done to develop successful therapies for these other types of hallucinations.


Thanks for reading!

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