The behaviourist view
The failure of introspection to reveal consistent
laws led to the rejection of all mental states as proper subjects of scientific
study. In behaviourist psychology, derived primarily from work of the American
psychologist John B. Watson in the early 1900s, the concept of consciousness was
irrelevant to the objective investigation of human behaviour and was doctrinally
ignored in research. Neo behaviourists, however, adopted a more liberal posture
toward mentalistic states such as consciousness.
Neuro Physiological Mechanisms
That consciousness depends on the function of the
brain has been known from ancient times. Although detailed understanding of the
neural mechanisms of consciousness has not been achieved, correlations between
states of consciousness and functions of the brain are possible.
Levels of consciousness in terms of levels of
alertness or responsiveness are correlated with patterns of electrical activity
of the brain (brain waves) recorded by an electroencephalograph. During
wide-awake consciousness the pattern of brain waves consists of rapid irregular
waves of low amplitude or voltage. In contrast, during sleep, when consciousness
can be said to be minimal, the brain waves are much slower and of greater
amplitude, often coming in periodic bursts of slow waxing and waning amplitude.
Both behavioral levels of consciousness and the
correlated patterns of electrical activity are related to the function of a part
of the brainstem called the reticular formation. Electrical stimulation of the
ascending reticular systems arouses a sleeping cat to alert consciousness and
simultaneously activates its brain waves to the waking pattern.
It was once supposed that the neuro physiological
mechanisms sub serving consciousness and the higher mental processes must reside
in the cortex. It is more likely, however, that the cortex serves the more
specialized functions of integrating patterns of sensory experience and
organizing motor patterns and that the ascending reticular system represents the
neural structures most critically related to consciousness. The brainstem
reticular formation should not, however, be called the seat of consciousness. It
represents an integrative focus, functioning through its widespread
interconnections with the cortex and other regions of the brain.
Unconsciousness
Also called Subconscious, the complex of mental
activities within an individual that proceed without his awareness. Sigmund
Freud, the founder of psychoanalysis, stated that such unconscious processes may
affect a person's behaviour even though he cannot report on them. Freud and his
followers felt that dreams and slips of the tongue were really concealed
examples of unconscious content too threatening to be confronted directly.
Some theorists (e.g., the early experimental
psychologist Wilhelm Wundt) denied the role of unconscious processes, defining
psychology as the study of conscious states. Yet, the existence of unconscious
mental activities seems well established and continues to be an important
concept in modern psychiatry.
Freud distinguished among different levels of
consciousness. Activities within the immediate field of awareness he termed
conscious; e.g., reading this article is a conscious activity. The retention of
data easily brought to awareness is a preconscious activity; for example, one
may not be thinking (conscious) of his address but readily recalls it when
asked. Data that cannot be recalled with effort at a specific time but that
later may be remembered are retained on an unconscious level. For example, under
ordinary conditions a person may be unconscious of ever having been locked in a
closet as a child; yet under hypnosis he may recall the experience vividly.
Because one's experiences cannot be observed
directly by another (as one cannot feel another's headache), efforts to study
these levels of awareness objectively are based on inference; i.e., at most, the
investigator can say only that another individual behaves as if he were
unconscious or as if he were conscious.
Efforts to interpret the origin and significance
of unconscious activities lean heavily on psychoanalytic theory, developed by
Freud and his followers. For example, the origin of many neurotic symptoms is
held to depend on conflicts that have been removed from consciousness through a
process called repression. As knowledge of psycho physiological function grows,
many psychoanalytic ideas are seen to be related to activities of the central
nervous system. That the physiological foundation of memory may rest in chemical
changes occurring within brain cells has been inferred from clinical
observations that: (1) direct stimulation of the surface of the brain (the
cortex) while the patient is conscious on the operating table during surgery has
the effect of bringing long-forgotten (unconscious) experiences back to
awareness; (2) removal of specific parts of the brain seems to abolish the
retention of specific experiences in memory; (3) the general probability of
bringing unconscious or preconscious data to awareness is enhanced by direct
electrical stimulation of a portion of the brain structure called the reticular
formation, or the reticular activating system. Also, according to what is called
brain blood-shift theory, the transition from unconscious to conscious
activities is mediated by localized changes in the blood supply to different
parts of the brain. These bio psychological explorations have shed new light on
the validity of psychoanalytic ideas about the unconscious.
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