Hallucinations and delusions are prominent aspects of psychosis, characterized by distortion of reality to a great extent. Hallucination is basically a sensory perception triggered in the absence of any physical stimuli, whereas delusion is a false belief of the individual developed on his own accord without taking into consideration the external reality.
Hallucinations are false perceptions that are experienced in a conscious state, in the absence of any external stimuli. These perceptions can be experienced by any sensory modality ranging from visual and auditory to nociceptive and thermoceptive senses.
When hallucinating, the person may experience some disturbance or movement in the peripheral vision, or hear faint noises, even though none of this is actually happening. One of the simplest examples of hallucination is a mirage, wherein a person sees water in the desert when it doesn't really exist.
Delusion is false belief developed due to incorrect conclusions about the external reality, mostly contrary to the norms of the society. A person is most often subjected to delusions when he is suffering from some mental or neurological illness and therefore, delusions play a crucial role in the diagnosis of various psychological illnesses.
Some common types of delusions are delusion of jealousy, delusion of control, religious delusion, etc. An example of delusional belief would be when a person feels that his/her partner is having an affair outside their relationship.
Hallucinations Vs. Delusions
Even though both are attributed to psychotic disorders like schizophrenia, a person may also experience hallucinations owing to brain damage, sleep deprivation, neurochemical activity in brain, recreational drug abuse (such as LSD or PCP), and meditation (which deprives the brain of oxygen).
On the other hand, delusion is most often caused due to mental disorders, including bipolar disorder, dementia, anorexia nervosa, and obsessive compulsive disorder (OCD). Delusions are, in fact, symptoms of delusional disorder, schizoaffective disorder, and schizophrenia.
A person experiencing hallucination owing to some hallucinatory drug would come to terms with reality when the effects of the drug subside. However, a person suffering from delusions will only come to terms with reality when the ailment he is suffering from is cured.
A person suffering from chronic hallucinations due to some illness is bound to seek treatment from a specialist, but a person experiencing chronic delusion will never seek treatment due to the lack of insight into his own condition.
This makes detection of delusion very difficult and the person suffering from such false beliefs may continue living with them for years together. Although the two concepts differ from each other, both are known to trigger intense fear in individuals, eventually compelling them to take an aggressive stance.
Initially, the person may feel shocked or helpless, but with time, the frustration may just increase and result in an outburst that may include harming themselves or other people around them. Although hallucinations and delusions are most often observed with patients suffering from mental illnesses, they need not always imply mental disorder.
The best measure to cure these disorders is to provide reassurance to the person experiencing them and take necessary measures to reduce their occurrence.