Consciousness is a state of the mind and brain generally marked by awareness. The term consciousness means different things to different people. Scholars who study consciousness believe it includes such features as attention, feelings, intention, and self-awareness. The scholars who study consciousness include neuroscientists—who investigate the brain and nervous system—as well as philosophers, psychologists, and even computer scientists. These people have tried to understand how consciousness arises from the cells and structure of the brain.
Many nonhuman animals show many of the characteristics of consciousness. But many scholars do not think other animals have consciousness. Some neuroscientists and philosophers argue that animal consciousness is not the same as human consciousness.
Types of consciousness.
Most scholars believe that there are different kinds of consciousness. One well-known approach divides consciousness into two fundamental types: core consciousness and extended consciousness. Core consciousness consists of basic elements of attention, emotion, purposeful behavior, self-awareness, and wakefulness. Core consciousness is necessary for extended consciousness. However, extended consciousness also includes the ability to recall one’s past and to imagine oneself in the future. Whereas core consciousness focuses on the here and now, extended consciousness includes past, present, and future. Scholars call this concept the autobiographical self. Humans possess extended consciousness. It may also exist in some intelligent animals, such as chimpanzees and dolphins.
Neuroscientists base their ideas about core and extended consciousness in part on studies of people with brain injuries. Some of these people appear to lose certain aspects of consciousness. For example, a person in a persistent vegetative state may have periods of wakefulness and sleep, despite remaining unconscious. But such a person may lack any self-awareness or purposeful action. Other people suffer a type of temporary memory loss called transient global amnesia. These people are awake and have a sense of self, but they may not remember parts of their own past. But these people still know that they are unique individuals distinct from those around them. They thus retain core consciousness even if they have greatly reduced extended consciousness.
There can also be different degrees of consciousness within each type. For example, drowsiness can be considered an example of reduced core consciousness.
How consciousness comes about.
Neuroscientists have observed certain changes in brain activity that correspond with various conscious states. For example, they know that a particular region at the base of the brain is important for attention and awareness. The neurons (nerve cells) in this part of the brain are relatively inactive during deep sleep. They are active while a person is awake. In addition, drugs called anesthetics are known to affect the neurons of the cerebral cortex (outermost part of the brain). The cerebral cortex is responsible for many of the higher brain functions of thought and behavior. Because anesthetics cause a loss of consciousness, scientists know some of the functions of consciousness must lie in the cerebral cortex.
Identifying individual areas of the brain involved with various aspects of consciousness is relatively easy. However, scholars have a hard time understanding how brain activity gives rise to conscious experiences, such as pleasure, pain, or the perception of color. Many neuroscientists and philosophers believe that this puzzle is one of the most challenging and important problems in science. They believe that consciousness is not centered in one or more specific areas of the brain. Rather, they think that consciousness more likely results from several brain areas working together.
Several neurological conditions may provide some insight into how the brain develops consciousness. For example, a condition called blindsight can result from damage to the back of the brain, in an area called the occipital lobe. Individuals with blindsight claim that they cannot see. While people with blindsight do not have full visual abilities, they can perform certain complicated visual tasks. In some cases, they can even catch an object thrown in their direction. To scholars, this contradiction suggests that conscious awareness of sight can be separated from vision.
Scientists have identified several regions of the brain related to the more basic elements of consciousness. More complex forms of consciousness likely involve these structures in addition to brain structures involved in the retrieval of personal memories and in foresight.
The function of consciousness.
Many scientists believe that complex consciousness—including the extended consciousness of human beings—must aid in survival. Yet many living things survive without it. Even the simplest animals have an awareness of their surroundings. This awareness enables them to find food and avoid predators (hunting animals). But most simple animals cannot manipulate their environment to the degree that organisms with more complex forms of consciousness can. Most scholars believe that consciousness helps humans avoid threats and take advantage of opportunities in their environment. Consciousness may be especially useful for problems requiring mental flexibility and group cooperation.
Scholars interested in the brain and mind have come up with many other questions about the nature and function of consciousness. Some philosophers wonder whether consciousness is a fundamental property of the universe, like matter or energy. They argue that attempts to understand consciousness simply as a matter of biology may be limited. Others wonder whether a machine, such as a computer, could ever experience consciousness. Neuroscientists and psychologists also study how mental states, such as dreaming or hypnosis, relate to consciousness.
See also Brain (Attention and consciousness) ; Phenomenology ; Psychology ; Subliminal ; Unconscious .
