Filtering determines which perceptual content reaches the thinking consciousness. Based on their perceptual memory and experience, each person has both culturally determined and personal filters. In people with psychosis, the brain‘s filters are more blurred than in the average person.
What is filtering?
Filtering determines what perceptual content reaches the thinking consciousness. Humans, by and large, hear and see what they want to hear and see. This is because human perception is characterized by filtering systems that block out the seemingly irrelevant and allow people to consciously experience only the obviously important stimuli of a situation. The evaluation of stimulus relevance is made in the brain on the basis of past perceptions, associated feelings, personal interests and values of the individual. The filter protects the consciousness from stimulus overload. If humans were to consciously perceive all stimuli, they would have difficulty finding their way through this jungle of stimuli. From an evolutionary point of view, the filter function, as an important part of perception, is also of great significance, as it enabled man’s ancestors to assess dangers more easily.
Function and task
The human brain has a clock frequency of one kilohertz. Closely connected synapses with different characteristics retrieve information in an efficient manner through chemical processes. In addition, the brain has storage capacities of about two petabytes. This corresponds to about 1000 times the capacity of a high-performance computer. Each of the human sensory systems has its own memory space. Sensory impressions are categorized, networked, classified, emotionalized, sensorially integrated, interpreted and linked to language in the brain on the basis of past perceptions. The functioning of the human perceptual apparatus also relies on filtering. This filtering takes place on the basis of the perceptual memory. Innumerable stimuli flow onto the human being every second. To consciously perceive all stimuli from outside would overtax the capacity of the human consciousness. Through the filter system, the human being consciously takes in only those stimuli from the surrounding world that he considers meaningful. For this purpose, the brain sorts out from perceptual impressions those stimuli which, on the basis of its experience, are of importance for the current situation. All other stimuli migrate into the subconscious and are thus filtered out. As a result of this filtering, people perceive birdsong, for example, only in the background or not consciously at all if they are currently engaged in an important conversation. The fact that people see this car model driving through the city more often after buying a certain car than before is also due to the brain’s perception filter. The latter example shows above all the evaluation function that the brain performs with respect to all perceived stimuli. Every person evaluates situations and the stimuli occurring in them according to his own filter system. Dieter Pabst names, for example, personal experience and one’s own ethics as relevant filters. Thus, in addition to upbringing, kindergarten, school and parental home, the circle of friends and culture also have an influence on an individual’s personal filter. Value systems for the personal filter include ethics and morals, conscience, ideological and religious views, ideas of justice, dogmas or superstition. Also the interests of the individual take filter function: so for example the occupation, the hobbies and the inclinations. Culture and cultural evaluations of sensory impressions thus form one part of the filter. The other part is formed by personal experiences and personal values based on upbringing, education, and interaction with other people. According to cognitive linguists, language, for example, represents the cultural filter. Language directs attention: for example, if there are 100 different words for snow in a culture, the speaker of that language must scrutinize fallen snow more closely for reference than the speaker of a language with only a single word for snow. The individual experiential filter of human perception, on the other hand, is closely tied to feelings, expectations, and values of perceptual memory.
Diseases and ailments
In some cases, the reality filter of brain-damaged patients no longer functions.The affected people then act on the basis of memory contents that are absolutely independent of the current situation. Severe memory disorders are usually associated with this phenomenon. In most cases, however, the affected people are not aware of these memory disorders. The patients’ brain gives way to memories and valences without situational relevance at the wrong moment. The brain’s reality filter normally retrieves from memory only those contents that have a relation to the present. In patients with this disorder, the brain is no longer capable of this process. Not only physical but also mental disorders can be accompanied by a misdirected filtering of perception. This is the case, for example, with psychoses. Usually, the filters in the brain are more or less sharply adjusted and help to recognize only those of current relevance in an abundance of stimuli and impressions. In people with psychosis, the filters are set much more blurred. For this reason, uncontrolled stimuli and associations flood in on them. The everyday consciousness of a person is relatively rigid because of the filters. That of a person with psychosis or schizophrenia, on the other hand, is highly dynamic and lively because of the low filter sharpness. This connection points to a link between genius and madness, as geniuses have always been said to be. Thus, the filters of a creative person are also more open to association than those of uncreative persons.
