A simple example of communication within the nervous system is the spinal arc, which is seen in the knee-jerk reflex. A tap on the patellar tendon, just below the kneecap, sends a signal to the spinal cord via sensory neurons. This signal activates motor neurons that trigger a contraction of the muscle attached to the tendon; the contraction, in turn, causes the leg to jerk. Thus, a stimulus can lead to a response without involving the brain, via a connection through the spinal cord.
Circulatory communication is ordinarily slower than nervous-system communication. The hormones secreted by the body's endocrine glands circulate through the body, influencing both structural and behavioral changes . The sex hormones, for example, that are released during adolescence effect many changes in body growth and development as well as changes in behavior, such as the emergence of specific sexual activity and the increase of interest in the opposite sex. Other hormones may have more direct, short-term effects; for instance, adrenaline, which is secreted when a person faces an emergency, prepares the body for a quick response-whether fighting or flight.
Psychoanalysis, name applied to a specific method of investigating unconscious mental processes and to a form of psychotherapy. The term refers, as well, to the systematic structure of psychoanalytic theory, which is based on the relation of conscious and unconscious psychological processes.
Theory of Psychoanalysis
The technique of psychoanalysis and much of the psychoanalytic theory based on its application were developed by Sigmund Freud. His work concerning the structure and the functioning of the human mind had far-reaching significance, both practically and scientifically, and it continues to influence contemporary thought.
The first of Freud's innovations was his recognition of unconscious psychiatric processes that follow laws different from those that govern conscious experience. Under the influence of the unconscious, thoughts and feelings that belong together may be shifted or displaced out of context; two disparate ideas or images may be condensed into one; thoughts may be dramatized in the form of images rather than expressed as abstract concepts; and certain objects may be represented symbolically by images of other objects, although the resemblance between the symbol and the original object may be vague or farfetched. The laws of logic, indispensable for conscious thinking, do not apply to these unconscious mental productions.
Recognition of these modes of operation in unconscious mental processes made possible the understanding of such previously incomprehensible psychological phenomena as dreaming. Through analysis of unconscious processes, Freud saw dreams as serving to protect sleep against disturbing impulses arising from within and related to early life experiences. Thus, unacceptable impulses and thoughts, called the latent dream content, are transformed into a conscious, although no longer immediately comprehensible, experience called the manifest dream. Knowledge of these unconscious mechanisms permits the analyst to reverse the so-called dream work, that is, the process by which the latent dream is transformed into the manifest dream, and through dream interpretation, to recognize its underlying meaning.
A basic assumption of Freudian theory is that the unconscious conflicts involve instinctual impulses, or drives, that originate in childhood. As these unconscious conflicts are recognized by the patient through analysis, his or her adult mind can find solutions that were unattainable to the immature mind of the child. This depiction of the role of instinctual drives in human life is a unique feature of Freudian theory.
According to Freud's doctrine of infantile sexuality, adult sexuality is an end product of a complex process of development, beginning in childhood, involving a variety of body functions or areas (oral, anal, and genital zones), and corresponding to various stages in the relation of the child to adults, especially to parents. Of crucial importance is the so-called Oedipal period, occurring at about four to six years of age, because at this stage of development the child for the first time becomes capable of an emotional attachment to the parent of the opposite sex that is similar to the adult's relationship to a mate; the child simultaneously reacts as a rival to the parent of the same sex. Physical immaturity dooms the child's desires to frustration and his or her first step toward adulthood to failure. Intellectual immaturity further complicates the situation because it makes children afraid of their own fantasies. The extent to which the child overcomes these emotional upheavals and to which these attachments, fears, and fantasies continue to live on in the unconscious greatly influences later life, especially love relationships.
The conflicts occurring in the earlier developmental stages are no less significant as a formative influence, because these problems represent the earliest prototypes of such basic human situations as dependency on others and relationship to authority. Also basic in molding the personality of the individual is the behavior of the parents toward the child during these stages of development. The fact that the child reacts, not only to objective reality, but also to fantasy distortions of reality, however, greatly complicates even the best-intentioned educational efforts.
Id, Ego, and Superego
The effort to clarify the bewildering number of interrelated observations uncovered by psychoanalytic exploration led to the development of a model of the structure of the psychic system. Three functional systems are distinguished that are conveniently designated as the id, ego, and superego.
The first system refers to the sexual and aggressive tendencies that arise from the body, as distinguished from the mind. Freud called these tendencies Triebe, which literally means "drives," but which is often inaccurately translated as "instincts" to indicate their innate character. These inherent drives claim immediate satisfaction, which is experienced as