Perceptual and Linguistic Filters

Biology

The first filter of mental models is the nervous system. We have physiological limitations that prevent us from perceiving certain phenomena with our senses. A commonly cited range for human hearing is 20 to 20,000 vibrations per second; dogs can hear higher frequencies and elephants lower ones. Cats see better in low light, and hawks can resolve distant detail that we cannot. The visible-light range given here is approximately 380 to 680 nanometres in wavelength, a small part of the electromagnetic spectrum.

We cannot respond directly to a signal we do not detect. A dog may hear a whistle that a person cannot hear. A bat can navigate in darkness using echolocation, while an unaided person may struggle. That's why we, humans, invent instruments such as sonar and radar to expand the perceptual reach of our senses and, consequently, our ability to act.

Our interconnection with the world is much more complicated than we think. The objective theory of perception states that the world "out there" creates direct changes and produces effects on the nervous system "in here." Challenging this theory, Humberto Maturana and Francisco Varela argue that the outside world can only produce disturbances in the nervous system. In their account, the structure of the nervous system helps determine how it responds to a disturbance. In The Tree of Knowledge, Maturana and Varela define the nervous system as a closed system. The passage contrasts their view with the following description, whose quotation is poorly transcribed here: "an instrument that gets information from the environment and builds a representation of the world, which the body uses to calculate the behavior appropriate for its survival. According to Maturana and Varela". In their account, experience arises within the organism; it is not direct access to the external world.

The theory also addresses how people can share experiences despite having no direct access to one another’s perceptions. Similar biology can produce similar responses, though it does not make every person’s experience identical. Maturana and Varela affirm that what the person experiences is "(reality)" and not "reality." Thus written, in parentheses, "(reality)" denotes the inner experience of the field of energies, external and unknowable, which we call "reality" without parentheses. We live in an inter-subjective (reality), not because the (reality) we see is the real, objective external reality, but because the environment awakens similar responses in our nervous systems.

The second filter of our mental models is language. Language is the medium in which the consciousness of the human being is structured. Language is the space of meaning in which reality appears intelligible and communicable. Thanks to language, we can communicate with ourselves and with others about what exists around us and within us.

The traditional understanding of language is "label theory." According to this theory, we see things in the world as they are and then apply a name, a label. This is the primary use of language: a descriptive system for labeling and classifying preexisting and therefore, independent perceptions. This theory is incomplete and only accounts for a very small function of language. The stronger view presented here is that linguistic categories help constitute perception. That is a theoretical claim, not a reason to conclude that people cannot perceive anything they cannot name.

An accountant "watches" a balance sheet for patterns that an engineer without accounting training might miss. Both can see the numbers; their knowledge gives them different ways to interpret them. An engineer can similarly "read" a system of differential equations that an accountant without that training may not understand. The ability to make distinctions and to order the world into operational categories is what is called "intelligence."