Have you ever been so tired, feverish, or just perplexed, you couldn’t with certainty tell whether the postman at the door was real? Or, have you been extremely concerned when your wife declared that even though David Bowie is dead, she was singing the Marseillaise with him in the kitchen last night? Is there a scientific explanation for these moments? Am I just going bonkers? Is my wife ill in some way? Was it an illusion or hallucination, or in fact, reality?
An illusion is a type of perceptual or cognitive error. Everyone suffers some of them sometimes. They can affect any sense, but the visual illusions are the most common. Depending on the stimulus, which is always present in case of illusions, the result will be ambiguous or paradoxical, but generally the same in most people. Painters, filmmakers and magicians take advantage of this phenomenon, big time.
We know that the Moon is not the size of an orange, and that a magician doesn’t really cut a woman inside the box with a chainsaw. Nevertheless, since everyone gets “tricked” the same way, some images can look very “realistic” and good magicians can certainly delight or scare an audience with their trickery.
Other types of illusions may confuse those who experience them into thinking the thing is something other than it really is. Perhaps a group of people standing outside at night believe they see something like a UFO, but in reality it is an optical illusion caused by lights in the sky.
Illusions can also occur when people have particularly strong beliefs or hopes that they will experience a given thing. Sometimes religion may be the source for such illusions. A person may wish so strongly that they see an angel in the church, that when light shines through a particular window onto a religious object that they convince themselves that the light is what they want it to be. But in the case of the illusion, the light must be present for this incorrect perception.
Unlike illusions that are distorted truth, hallucinations are not based on one. What is experienced is not based on any form of reality that others may perceive. No external stimulus is present for any of the types of perception, be it visual, auditory, olfactory (smell), gustatory (taste), or tactile (touch).
Hallucinations are mostly confined to people with mental illnesses, but also to those who suffered brain damage as a result of trauma, infection, intoxication by drugs or alcohol, and some other conditions. A person suffering from delirium tremens as a result of alcoholism may feel lice crawling over his skin or be frightened by red spiders and pink elephants. Schizophrenic patients often hear voices of their persecutors, their own conversation with others, or their own thoughts spoken aloud (echo de pensée).
Play the video below to hear something like what a person with schizophrenia might hear during an auditory hallucination:
Additionally, imaginings as immediate and vivid as perception but not mistaken as such, are called “pseudo-hallucinations.” Those are most often a result of extreme emotions, exhaustion, or stress. For instance, Shakespeare’s Macbeth, planning to murder Duncan, “seeing” a dagger…”Art thou not, fatal vision, sensible to feeling as to sight? Or art thou but a dagger of the mind, a false creation, proceeding from the heat-oppressed brain?”
There are individual differences with regard to hallucinations. The same individual may experience different hallucinations on different occasions, which can involve more than one sense at the same time, but more often focus on one. The nature of the hallucination is determined by the individual’s present and previous experiences.
What is the root cause in the brain of hallucinations? “One major theory is that hallucinations are caused when something goes wrong in the relationship between the brain’s frontal lobe and the sensory cortex, said neuropsychologist Professor Flavie Waters from the University of Western Australia. For example, research suggests auditory hallucinations experienced by people with schizophrenia involve an overactive auditory cortex, the part of the brain that processes sound, said Professor Waters.”
Not all hallucinations are intrusive, scary or negative, even in mental illnesses like schizophrenia. And as mentioned earlier, hallucinations can be benign and experienced by people without diagnosable illnesses or drug activity at all. People have been known to experience hallucinations during the process of falling asleep. Factors such as lack of sleep, stress, trauma and grief may also upset the relationship between the brain’s sensory cortex and the frontal lobe.
An interesting question I’d like to ponder more is the one in this post’s title. Does truth always matter? After all, many people in history who have been subject to illusions choose to believe the illusions as true, despite science (or even logic) telling them that they’re not. Those who hallucinate who believed the hallucinations to be true may eventually realize they were not, while others believe them true indefinitely. Even if a person hallucinates and realizes immediately that it is not reality (this can be the case) may be somehow affected by experience. There’s good and bad in all cases, as well as advantages and disadvantages.
What are your experiences with illusions and hallucinations, if you’ve had any? Are there experiences you’ve had that you truly believe were true, that others insist were not?