Since our perception never corresponds one hundred percent with reality, the boundary to perceptual illusions or disorders is fluid. For example, we perceive colors even though light itself is not colored, but only has different wavelengths that are interpreted accordingly by the visual organ and brain; many animals, for example, perceive colors differently than humans.
Optical illusions and perceptual disorders.
Although the line between optical illusions and perceptual disorders is blurred, there are differences:
- Optical illusions as – normal – visual impressions that contradict objective stimulus facts are probably familiar to everyone. They result from the construction and functioning of the eyes, misinterpretations or misjudgments. For example, if one places a dot in the middle of six small dots and six large dots and looks at these two images side by side, the dot in the middle of the small dots appears larger than in the other image. Another example is two parallel lines that appear curved when a ray grid is placed between them.
- Perceptual disorders, on the other hand, are the cause of a – temporarily or permanently – restricted or defective function of the sensory organ itself, the conduction pathway or the brain. Typical examples are hallucinations – perceptions in which there is no external stimulus – for example, as a result of exposure to toxins (alcohol, drugs), in physical diseases (for example, epilepsy) or mental illness (for example, schizophrenia). To the person affected, this perception appears real. In contrast, in pseudohallucinations, such as those that occur during sleep deprivation, the affected person realizes that he or she is hallucinating. In delusional perceptions, real stimuli are present, but these are pathologically reinterpreted (for example, a random car horn is perceived as a personal signal).
In relation to the continuous exposure to stimuli from the environment, perceptual disorders occur rather rarely – a sign of what a feat our organism constantly performs.
Perceptual disorders are rare
In relation to the continuous stimulus impact from the environment, perceptual disturbances occur rather rarely – a sign of what a masterstroke our organism is constantly performing.