What is Consciousness? - Definition & Explanation

Instructor: Robert Turner
This lesson introduces you to psychological perspectives on consciousness. We will begin with an explanation of the difficulties involved in explaining consciousness, much less defining it. We will then consider an overview of psychological perspectives on consciousness states.

What Is Consciousness?

One of the most influential of the early Christian church fathers, St. Augustine of Hippo (354-460 C.E.) pondered the nature of time. In Book 11 of his Confessions, he wrote, What then is time? If no one asks me, I know: if I wish to explain it to one that asketh, I know not.

The very same may be said about the nature of consciousness. We know what it is because we experience it, but if someone asked you to define consciousness, what would you say? It's not something we can pour into a bottle, or lay out under a microscope. In fact, the mysterious, subjective quality of consciousness continues to challenge modern psychologists. In that light we can identify two main perspectives: reductionist materialism and what researcher Donald D. Hoffman calls conscious realism.

Reductionist Materialism

Reductionist materialists offer differing models and ideas about the nature of consciousness, but all of them share one common principle: namely, your consciousness is a product of your brain. Under that assumption, many hours of research have explored the nature of the brain and how it goes about producing thoughts, ideas, memories, and visual impressions. For example, the use of MRIs has enabled researchers to locate the parts of our brain that respond to visual images, music, logic, and emotions. The image below offers you a synopsis of this sort or reasoning.

From Perception to Awareness
from perception to awareness

In the image, a man views a scene in the outside world. The brain then interprets the scene as different areas of the brain activate specific neurons (brain cells) and connections among neurons (synapses). The conscious image that emerges allows us to see the dog.

The reductionist view is dominant in modern psychology. This is the case because thousands of experiments have shown that different kinds of damage to the brain and nervous system alter people's consciousness states.

Conscious Realism

Science does not stand still. As more information is gathered, new hypotheses are formulated and tested. Under the influence of findings in theoretical physics, and quantum mechanics in particular, radical new ideas about consciousness are now 'on the table.'

One of these, called 'conscious realism,' has been proposed by Donald D. Hoffman of the Department of Cognitive Science at the University of California, Irvine. Hoffman, drawing on ideas from theoretical physics, proposes that consciousness is an inherent property of the universe. It is consciousness that organizes matter-energy and not the other way around. Therefore, while consciousness states and brain functioning are clearly correlated, the mind is not the brain.

The idea that consciousness is prior to matter is mind-boggling. So, you may ask, why bring it up in a lesson like this one? That's a good question that leads to an uncomfortable answer: basic questions about consciousness, such as the relationship between the mind and the body, have not been resolved. To tell you otherwise would be to mislead you. The ultimate nature of reality remains a mystery and, thus, a spirit of open-minded inquiry is simply good science.

Consciousness States

The study of consciousness states is a very basic area of research for psychologists. It cannot answer all our questions about consciousness, but it can provide useful clues.

Ordinary waking consciousness is generally viewed as a baseline by which to evaluate altered states of consciousness, including the following:


Sleep lab experiments have helped us understand sleep cycles. Electroencephalogram (EEG) readings track the brain wave patterns of subjects. In this way, five stages of sleep are identified. Four of them are called NREM, meaning non-REM or 'dreamless sleep.'

  • NREM stage 1: Here we are at the boundary of sleep and wakefulness. Your muscles remain active. Your eyes roll slowly, your eyelids half open, half closed. Others see you are 'half asleep.'
  • NREM stage 2: Your brain wave activity changes. You are less easily awakened. Clusters of spiky waves called sleep spindles appear in your EEG readout.
  • NREM stage 3: Your brain waves are now slow and lazy delta waves. You are oblivious to your surroundings, having entered the valleys of deep sleep.
  • NREM stage 4: You are way under now as stage 3 sinks into stage 4.
  • REM stage 5: Most of your muscles are paralyzed as your eyes shift about rapidly under your eyelids. Visions and images tell stories you will find hard to remember when the alarm clock goes off.

REM sleep is also called paradoxical sleep because your EEG waves will be quite similar to those we find when you are awake. However, it's harder to wake up people in REM sleep than it is in any other sleep state. REM sleep begins some 90 minutes into sleep and reoccurs more frequently near the end of a sleep period.


Hypnosis is an altered state that can be induced during ordinary waking consciousness. Stage hypnotists can persuade people to crow like a rooster or become convinced that their arm is too heavy to lift. On the other hand, light hypnotic trance states can occur without the aid of a spinning disc or the suggestions of a hypnotist. On a long familiar drive, have you ever realized that you've covered several miles without recalling doing so? Have you ever gone into a dreamy, blank mind state from the swish-click, swish-click of windshield wipers? Guess what? You were in a light trance state.

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