Binary classification as a cognitive strategy? Is there any research investigating whether the human cognitive system has a tendency to reduce complex systems or spectra of data in terms of binary contrast?

There are many common-sense dual taxonomical sets. Some of these have a basis in objective reality (the binary male/female has proved an especially effective evolutionary strategy), others may be argued to be more in the eye of the beholder. Day and night could be said to be extremes in a cycle; left and right, conservative and liberal are ranges on a spectrum (cf. friend and foe; "there are only two kinds of people"). A lot has been written about gender identity and sexual orientation in the framework of a Hegelian master/slave dialectic, but I am not interested in the relationship between the members in an oppositional set. Structuralist theorists and anthropologists have claimed and then disclaimed that societies organize themselves in binary sets, but more interesting to me than factual organization is how reality is perceived. Also, when an anthropologist or theorist says most concepts are defined by contrast with their opposites, I can't help but wonder whether we have quantifiable data along these lines.

I am hoping to find out whether these common-sense binary taxonomies correlate with cognitive/perceptive processes. Especially interesting to me is the question whether there are certain low-level cognitive strategies, though I am also interested in high-level processes (e.g. formal logic is mostly organized along binary lines, true/false). Since the cognitive sciences are not my field, I would be very grateful for references to both foundational studies and "raw" field work. General works on the reduction of reality to accommodate limited processing power are also welcome. Visual processes are not my primary interest, but if you can point to a single "best primer" on the filter that allows us to "see" an entire bookcase but not all book titles in a single glance, that would be a helpful bonus. I know nothing about the workings of biological neural networks, but if there is a binary selection at any point in their operation, I would be very grateful to see that explained in an accessible but peer-reviewed text. Finally, keywords to help me find more on this in scholarship search engines would be most helpful.
I think there is a misperception at work in your question. There is a wide variety of objects that we never perceive in such a binary manner: colors, fruit (apples, oranges, plums, ...), weather, and basically every other concrete objects. The only things we perceive in a binary fashion are abstract ideas! Good versus evil. Liberal versus conservative. And here we can ask about the reality (which is more complex) and the function of this simplification. The answer is: speed of decision making.

The basic binary classification is negation: x versus not x. The usefulness of this distinction becomes apparent when you put it in context: Is this berry edible or not? Do I want to trust this person or not? All binary opposites have a negation at their basis and divide the world into things you want to avoid and things you want to interact with.

And since human beings have to decide about one million things every day, they make life easier by using heuristics to make most of these decisions: simple rules based on experience, so you don't have to think before you vote for your next president.

The few binaries that are more or less objective, are categories of measurement: long/short, hot/cold, bright/dark, etc. That the physical reality underlying these measurements is maybe more complex (e.g. coldness depends not only on temperature, but also on the humidity of the air and the speed of the wind), is not relevant to the one-dimensionality of our sensation.

Night and day is not binary, since we have dawn and dusk and late afternoon and early morning and the dead of night as well to differentiate subjective time, relative visibility, quality of light, restedness/tiredness etc., that all make up the meaning of "night", "day" and other daytime names. The phrase "day and night" is binary only in certain phrases where they have symbolic meaning (e.g. "day" = good, "night" = evil, or "working night and day" = working all the time, without resting).



Studying the development of thinking styles in college students, Perry (1970) found that as they grow their thinking advances from a dualistic black-and-white perspective to a multiplicity of truths that allows for uncertainty. They also grow from a purely intellectual to an ethical perspective. In the course of this development, dualistic thinking can serve as an alternative to forward progression, and persons that already have developed to a higher level of thinking can use dualistic thinking as a "retreat" (Zang, 2002): "a student returns to a dualistic orientation to find security and the strength to cope with an overchallenging environment".

Binary thinking is related to personality disorders such as borderline personality and narcissism (Oshio, 2012): "The results indicated that thinking dichotomously may lead to
wide-ranging personality disorders."



Sources:


Oshio, A. (2012). An all‐or‐nothing thinking turns into darkness: Relations between dichotomous thinking and personality disorders. Japanese Psychological Research, 54(4), 424-429. doi:10.1111/j.1468-5884.2012.00515.x
Perry, W. G. (1970). Forms of intellectual and ethical development in the college years: A scheme. New York: Holt, Rinehart and Winston.
Zhang, L. F. (2002). Thinking styles and cognitive development. The Journal of Genetic Psychology, 163(2), 179-195.