Evolution of Human Consciousness

* Book: Merlin Donald. A Mind So Rare: The Evolution of Human Consciousness.

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Summary

By Trevor Stone:

"In the ten years after Origins of the Modern Mind was published, the cognitive science field changed significantly. Authors released a host of books with popular audiences in mind. The laboratory was supplemented with, and in some cases largely replaced by, a heavy dose of the armchair. The evolutionary psychology camp are among the most vocal of these authors, and may be the most influential among casual readers. These fundamentalist neo-Darwinists attempt to explain all aspects of the human mind by appeal to the principles of natural selection. In the process, most of them downplay or try to eliminate consciousness in the picture of cognition.

Donald begins AMSR by distancing his view of consciousness from that of what he calls "the Hardliners:" camp of neo-Darwinists and other reductionists, such as postmodernists. His project is to give a positive account of consciousness and how it came about. Unfortunately, Donald doesn't argue against any specific Hardliner arguments, nor does he credibly present the Hardliner views of his theory's key elements. The reader is thus left without a good understanding of why people hold Hardliner views. While this is philosophically somewhat disappointing, Donald's goal isn't so much to refute the Hardliners as it is to present his own theory on its own merits. His occasional jabs at Hardliners are meant to provide some context rather than to present a complete picture of existing work.

Although he doesn't respond to many specific arguments, Donald does battle with some commonly held beliefs, most remarkably by arguing in favor of a homunculus. He thinks that the "homunculus is heresy" idea is something of a knee-jerk reaction, and points out that Hardliners replace a single man-in-the-head with a cadre of men-in-the-head, even more impenetrable than the original, without explaining perceptual unity. In Origins, he says the homunculus "cannot be explained away as an epiphenomenon, "reduced" to algorithms or neural nets, or simply denied existence." (p. 365) The homunculus is what is to be explained, and in AMSR he aims to do so without invoking the spectre of Dualism.

After revealing his biases, Donald sets out to give an account of human consciousness while acknowledging that a complete account is many years away. His goal is to describe consciousness at the functional level, rather than providing an evolutionary account or a full description of how neurological activity produces consciousness. However, as a neuroscientist, he builds this functional model upon facts about the brain. He aims for an inclusive view of consciousness, "a multilayered, multifocal capacity and a deep, enduring cognitive system with roots far back in evolution." (p.10) For Donald, the words "consciousness" or "awareness" encompass many phenomena. The first is mental states such as sleep, wakefulness, and alertness. Second, consciousness is a central executive in the mind -- a self-regulating high-level processor that receives input from many sources, examines it, and directs action based on analysis. This form of consciousness is what we sometimes call thought or understanding. Functionally, such consciousness is domain-general processing power, attention, and general-purpose skill that can be brought to bear on unfamiliar or complex tasks. Finally, the third form of consciousness "has more to do with enlightenment, or illumination, than with mere attention," playing upon human symbolic capacity rather than just attention.

Fundamentally, Donald's theory of consciousness is quantitative rather than you-have-it-or-you-don't. Beings (animals so far as we know, but in principal computers as well) can be more or less conscious. Their conscious capacity can support more or less information. They can handle problems of varying levels of complexity. They may have the first form of consciousness but not the other two, and so on. With this backdrop, Donald allows many animals into "The Consciousness Club," starting with creatures like ants and bees which can construct a representation of the world divorced from their immediate sensory input. At progressively higher levels of consciousness are fish and vertebrates, birds, mammals, primates, and humans. Further, not all humans share the same level of consciousness, and a child becomes more conscious as she develops. Despite the views of some philosophers, and perhaps common sense, consciousness isn't like a light switch. Furthermore, more consciousness is not always better. Awareness comes at a resource cost, and most animals are able to thrive in their ecological niche without much consciousness.

Donald then presents the evolution of human consciousness.

He groups the constituents of consciousness into three "levels of awareness."

• The first, associated with the sensory cortex, is binding or perceptual unity, the ability to combine perceptions to perceive complex phenomena like objects and events. This is the domain of "raw feeling."

• Level-2 awareness, which developed with the secondary cortex, is the domain of short-term memory and control. Here, birds and mammals have a sense of time and can focus on both an immediate perception and something which is out of sight but no longer out of mind. Such animals can also use their conscious power to learn new skills and create a new subconscious demon for them.

• Finally, humans and some other primates possess level-3 awareness, courtesy the tertiary cortex. We are able to maintain intermediate-term awareness, at the level of minutes or hours. We are able to perceive, dissect, and act upon very complex situations and events, and several of them at once. Level-3 is episodic awareness, as described in Origins.

Donald makes a big deal out of the intermediate-term awareness afforded by level-3 awareness. Results from clinical research indicate that people are remarkably limited in the here-and-now. The "seven plus or minus two" rule for short-term memory, its rapid degradation, and other findings understandably fuel the reductionist Hardliners. But Donald illustrates common human activities that seem to break these constraints demonstrated in the lab. In an ordinary conversation, a person may track far more than 9 things, including major points made by each speaker, rebuttals that have already been made, facts about the subject matter in question, points she has thought to make when the right opportunity presents itself, and so on, all on a scale of tens of minutes or even hours. Donald's example adds to the cognitive load even more by supposing that the conversation participants don't all share a common language. The intermediate-term is the domain of consciousness, which is brought to bear in everything from reading a book to pursuing a goal in the face of obstacles. In such a home, consciousness can coexist with fast, specialized modules for basic and time-critical tasks because their work is separate but linked.

Level-3 awareness is not sufficient for symbolic thought and culture, as Donald demonstrates with the examples of enculturated apes. Humans departed from their primate cousins, Donald thinks, by developing a superplastic brain and complex webs of culture, neither of which can feasibly exist without the other. "Deep" or "cognitive" enculturation is thus added to genes and environment as a driving factor of development. Deep enculturation, unlike the basic social environment, can alter the cognitive architecture, installing new modules and demons.

To demonstrate his point about deep enculturation, Donald leads the reader through the Condillac's statue thought experiment. Condillac asked his readers to imagine how a statue granted limited sensory power (such as just smell or smell, sound, and vision) would learn about the world. Condillac concluded that only once the statue had the powers of touch, action, and internal sensation (even without the other four senses) could it become fully conscious and thus understand the world in anything resembling a human way. "This," says Donald, "conveys one central tenet of Constructivism: Action begets self-knowledge."

Donald then presents a real-world "statue" in the story of Hellen Keller. After a year and a half of normal infant development, Keller lost her senses of sight and hearing, restricting her cognitive development for several years. Keller could communicate mimetically, modulated by her range of possible inputs, and had an internal model of the world, but couldn't communicate linguistically and had poor, if any, symbolic powers. After arduous attempts to teach her language through haptic sign language proved unsuccessful Keller's teacher, in a fit of frustration, signed "water" and then dunked Keller's hand in a bucket of water. This produced an epiphany as Keller realized the connection between symbols and her understanding and experience of the world. Symbolic capacity thus instilled, or at least linked to her sensory modality, Keller then quickly learned how to communicate linguistically through both haptic sign language and braille. She went on to lead a life of educated success that people with all normal senses would find quite challenging.

The example of Hellen Keller provides, in one glimpse, an understanding of Donald's arguments against modularity of high-level language and symbolism and in favor of deep enculturation and the mimetic/symbolic divide. Keller acquired language several years after most children and through several modalities, none of which were evolutionarily expected. Her superplastic human brain adapted to her unique experiences to allow her to lead a cognitively normal, if perceptually limited, human life. Since there is no selection pressure for the deaf and blind to learn language, the modularist has quite a bit of work to do to explain how Keller was able to develop skilled and full-fledged language.

The final two chapters of AMSR present a condensed version of the three transitions Donald describes in Origins, this time with an eye toward consciousness. I felt that these chapters provided an easier understanding of the key concepts of Origins, though I may have found it thus because I'd already understood Origins, and this section was mostly focused review. The material in these chapters is mostly covered in the above summary, so I will not repeat them here."

(https://trevorstone.org/school/donaldreview.html)

More information

See the other, earlier, book by the same author:

• Origins of the Modern Mind: Three Stages in the Evolution of Culture and Cognition. By Merlin Donald. 1991