Copyright © Allyn & Bacon 2008 Chapter 8 - Mechanization and Quantification A History of Psychology: Ideas and Context (4 th edition) D. Brett King, Wayne Viney, and William Douglas Woody This multimedia product and its contents are protected under copyright law. The following are prohibited by law: any public performance or display, including transmission of any image over a network; preparation of any derivative work, including the extraction, in whole or in part, of any images; any rental, lease, or lending of the program

Copyright © Allyn & Bacon 2008 Mechanization Mechanism emerged as a philosophical perspective. Thomas Hobbes argued that the subject matter of philosophy is the motion of physical bodies. –He used a mathematical method in the rationalist tradition. –He was a nominalist in that he advocated the use of reason to provide names and classification systems. –Hobbes was also a thoroughgoing materialist. He argued that God is a material being. –Hobbes believed that human nature was self-serving. Humans can suppress these urges largely through fear of the state.

Copyright © Allyn & Bacon 2008 Mechanization and Descartes René Descartes was interested in the problem of movement in physical bodies. –He endorsed a hydraulic model of movement. Human and animal bodies are complex machines. –Descartes argued that the ventricles of the brain stored animal spirits. Movement was enabled when animal spirits flowed down a nerve pipe to the muscle. The muscle then inflated with animal spirits and stimulated movement. The flow of animal spirits was regulated by small threads that opened valves in the ventricles in response to an environmental stimulus.

Copyright © Allyn & Bacon 2008 Mechanization and Descartes Descartes argued that the mind-body interaction particular to humans takes place in the pineal gland. He proposed the following claims regarding the pineal gland. –The pineal gland is found only in humans. –The pineal gland is richly supplied with nerves. –The pineal gland can move freely from side to side. Additionally, Descartes provided the following testable hypotheses for future researchers. –Muscles are literally inflated by animal spirits. –The muscular system is tied to the ventricles of the brain, the source of animal spirits. –Nerves have both sensory and motor functions. –Nervous transmission is extremely fast.

Copyright © Allyn & Bacon 2008 Mechanization and Descartes Jan Swammerdam tested Descartes’s hypothesis that muscles are inflated by animal spirits flowing from the brain. –He demonstrated that a frog muscle can contract even if separated from the frog’s brain. –He also demonstrated that a muscle can contract even if cut. According to Descartes, the cuts would allow the animal spirits to leak out. –He demonstrated that muscles do not inflate when they contract.

Copyright © Allyn & Bacon 2008 Mechanism and Descartes Neils Stensen questioned Descartes’s assertions regarding the pineal gland. –He argued that the pineal gland cannot swing from side to side. –He demonstrated that the pineal glad is not richly supplied with nerves. –He located the pineal gland in non-human animals.

Copyright © Allyn & Bacon 2008 Mechanization and Descartes Stephen Hales established the importance of the spine in the reflex. –He demonstrated that a decapitated frog could exhibit reflexes if the frog’s spinal cord was intact. Robert Whytt replicated the work of Hales and more thoroughly studied the role of the spinal cord in reflexes. Whytt also addressed the distinction between voluntary and involuntary actions.

Copyright © Allyn & Bacon 2008 Mechanization Johann August Unzer provided a systematic framework for the reflex action. –He was the first to use the terms “reflex,” “afferent,” and “efferent.” –Unzer applied his theory to the practical questions of pain and the guillotine. Julien Offray de la Mettrie wrote L’Homme, la Machine (Man, a Machine). –He advocated a thoroughgoing materialism and determinism. –He argued that the differences between humans and animals were differences of degree. Pierre Jean Georges Cabanis argued that psychological processes are a consequence of neurological activity.

Copyright © Allyn & Bacon 2008 Mapping the Nervous System The Bell-Magendie Law reflected the discoveries of the localization of function of afferent and efferent roots of the spinal column. Sir Charles Bell established the motor functions of the spinal cord. François Magendie demonstrated the sensory root of the spinal cord. Johannes Müller argued for further localization of function. –He proposed the doctrine of specific nerve energies. –He argued that qualities of the nerve caused the qualities of perception within a given sense. –He argued that a nerve is only capable of transmitting one type of sensation. –Müller’s work was extremely influential for the trichromatic color theory of Thomas Young and Hermann von Helmholtz.

Copyright © Allyn & Bacon 2008 Localization of Function Franz Joseph Gall and Johann Kaspar Spurzheim launched a productive false start in the form of phrenology. Phrenology became a popular approach to mind in Europe and the United States. The main premises are as follows. –Mental functions are localized within the brain. –The surface of the skull conforms to the relative development of brain tissue related to the specific faculty under that area of the skull.

Copyright © Allyn & Bacon 2008 Localization of Function The work of Gall and Spurzheim mobilized other researchers to investigate localization of function. –Pierre Flourens studied brain function through lesions of specific areas of brain tissue. He found some localization. He also demonstrated neural plasticity. –Paul Broca argued that the motor coordination of spoken language is not localized where the early phrenologists claimed. He established Broca’s area with an autopsy of an individual with aphasia. Carl Wernicke found the localized Wernicke’s area, the area of the brain related to speech comprehension.

Copyright © Allyn & Bacon 2008 Extending Powers of Observation The X-ray, the microscope, and other tools, enabled researchers to extend the powers of observation in neuropsychological research. –Gustav Theodor Fritsch and Julius Eduard Hitzig initiated research in electrophysiology. They demonstrated localization of motor functions. –Camillo Golgi created a staining procedure. –Santiago Ramón y Cajal described the synaptic gap by using Golgi’s staining procedure.

Copyright © Allyn & Bacon 2008 Extending Powers of Observation Sir Charles Sherrington published The Integrative Action of the Nervous System. –He demonstrated the complexity of neural action. –He coined many of the terms used in neuroscience. Hermann von Helmholtz measured the speed of a nervous impulse. –Neural impulses were surprisingly slow. –His success fueled optimism about the power of science.

Copyright © Allyn & Bacon 2008 Quantification New techniques and uses of quantification enabled measurement of behavior. –Developments helped to make the science of psychology possible. Mathematical work in probability had been underway since the work of Pascal and others. Only later did researchers apply the new statistics to the measurement of behavior.

Copyright © Allyn & Bacon 2008 Jacques Quételet Jacques Quételet is relevant to the history of psychology in two primary ways. –He argued that human behavior is subject to the laws of nature. –He was able to mathematically relate external factors and human behavior. Quételet studied both physical traits and moral or psychological qualities and noticed that the distributions were very similar. –Quételet is responsible for the idea of the homme moyen, the average man. –Quételet’s data reinforce the importance of the study of development,individual differences, and the relevant differences between people in various places on the normal curve.

Copyright © Allyn & Bacon 2008 Francis Galton Sir Francis Galton pioneered new statistical techniques. He applied measurement to a wide variety of topics including the following. –the efficacy of prayer –the heritability of physical and psychological traits. Later in his life, he applied these interests to the field of eugenics.

Copyright © Allyn & Bacon 2008 Practical Applications Measurement techniques were used to justify racial and gender prejudices by quantifying apparent differences in intelligence and abilities. Florence Nightingale used statistical data to examine medical records. –She was the first to use graphs to illustrate her arguments. Dorthea Lynde Dix used descriptive statistics in her campaigns to improve conditions for the mentally ill.