People can be conscious about their surroundings even when they appear not to be.
Conscious experiences are associated with brain activity. People manipulate conscious
experiences through natural methods – meditation, as well as artificial methods – drugs.
Conscious experiences differ from person to person. Consciousness refers to moment-by-
moment subjective experiences. You are conscious of only certain things that happen, for
example, you are not conscious of the metabolic processes going on in your body. We can
never know if people are experiencing the world similarly because each of us experiences
consciousness subjectively. Conscious experience can be seen as unified and coherent. The
mind is a continuous stream and thoughts float on that stream.
Automatic tasks are done with little or no conscious effort. Unfamiliar or difficult tasks
require greater conscious effort. Such controlled processing is slower than automatic
processing, but it helps us perform in complex or novel situations.
Consciousness lets us perform complex actions that may require input from several
different brain regions; it can help us connect with one another by sharing thoughts and
feelings and even imagining ourselves in another person’s situation; it is required for
complicated thinking, such as understanding the development of a plot in a story, using
logical reasoning, and performing mathematical calculations.
Coma: allows the brain to rest; sleep/wake cycles where the patient can open and close his
eyes but not respond to his surroundings; the brain can sometimes process information in
this persistent vegetative state; but the persistent vegetative state is not associated with
consciousness, normal brain activity does not occur in this state mostly because part of the
person’s brain may be dead; cortical regions known to be important for consciousness
Between vegetative state and fully conscious state is the minimally conscious state where
people make some deliberate movements, and may try to communicate.
Brain activity gives rise to consciousness. Scientists can identify objects you are seeing by
looking at your brain activity. Using fMRI, scientists can decipher whether you are seeing a
house, a shoe, a bottle or a face. Brain imaging can determine whether a person is looking
at a striped pattern that is moving horizontally or vertically, whether a person is looking at
a picture or a sentence, which of three categories a person is thinking about during a
memory task, and so on.
Consciousness can be measured and examined.
The global workspace model posits that consciousness arises as a function of which brain
circuits are active. You experience your brain regions’ output as consciousness.
Hemineglect patients are unaware of their visual deficits due to brain damage. This model
presents no single area of the brain as responsible for general “awareness”.
The major connection between the hemispheres that may readily be cut without damaging
the gray matter is the massive fibre bundle called the corpus callosum. When the corpus callosum is severed, the brain’s halves are almost completely isolated from each other
resulting in what is called split brain. Split brain patients have no immediate apparent
problems. However, just as the brain split in two, so had the mind.
The left hemisphere is associated with language. When a patient with split brain is flashed
two images, he will only see the image on the right. Know that the left side of the brain
controls the right side of the body and vice versa. The right hemisphere has no discernable
language capacity. The mute right brain, having seen the picture, is unable to articulate a
response. The right part of the brain can act on its perception though. If it sees a spoon, the
right hemisphere can actually pick out a spoon from a bunch of objects. Splitting the brain
creates two half brains. Each half has its own thoughts, perceptions and consciousness.
The right half of the brain is good for spatial relationships.
Both hemispheres work together to reconstruct our experiences.
The left hemisphere’s propensity to construct a world that makes sense is called the
interpreter. The left hemisphere is interpreting what the right hemisphere has done and
attempts to make sense of actions and ongoing events. When a hemineglect patient is
flashed “STAND UP” on the right hemisphere (left side) the patient will get up and when
asked why, he will say, “I felt like getting a soda” and not, “you told me to”.
A man was presented with a picture of a phone on the right hemisphere (left side) and
when asked what he saw, the patient said nothing. However, when given a pen and asked to
draw what he saw, his left hand started drawing a phone. The patient had difficulty saying
what the drawing was, and it was only until he finished the drawing did he know what he
drew. The communication between hemispheres happened on paper and not in the brain.
The left hemisphere may force people to search for patterns that might not even exist.
Unconscious processing influences behaviour. We are aware of some mental processes and
unaware of others. Subliminal perception is the processing of information by sensory
systems without conscious awareness.
Freudian slip is when an unconscious thought is suddenly expressed at an inappropriate
time or inappropriate social context.
Many brain regions are more active during sleep. Brain activity and other physiological
processes are regulated into patterns known as circadian rhythms. Circadian rhythms are
influenced by cycles of light and dark. However, humans and nonhumans continue to show
these rhythms even when removed from light.
Information about light detected by the eyes is sent to a small region of the hypothalamus
called the suprachiasmatic nucleus. This region then sends signals to the pineal gland
which secretes a hormone called melatonin. Bright light suppresses the production of
melatonin. Taking melatonin can help people fall asleep.
Gene SLEEPLESS regulates a protein that reduces action potentials in the brain.
Sufficient sleep is important for memory, and good health, and is often affected by
psychological disorders, such as depression. Sleep is an altered state of consciousness.
There are stages of sleep.
At stage 3 or 4, parents can be woken up by children’s cries but not sirens of higher
After 90 minutes