Physiological Roots of Psychology

Contributions to Founding of Psychology

• Philosophers– Deductive and inductive reasoning– Raised many of the basic questions

psychological research addresses today

• Physiologists– The methodological systems for testing

proposed answers to these questions

Goals of early physiological research

• Neuroanatomy – attempted to determine if function could be localized in the nervous system and how it was localized

• Neurophysiology – attempted to identify how nerves worked

Major contributors

• Neuroanatomy – Gall, Flouren, Broca, and Wernicke

• Neurophysiology – Bell, Magendie, Muller, and Helmholtz (Mentor to Wilhelm Wundt)

Function of the spinal nerves

• Difference in function between dorsal nerves, entering the back of the spinal cord , and the ventral nerves leaving the front.

• Magendie – French physician– 1822 – described the function correctly dorsal nerves

carry snsory information; ventral related to movement– Experimental methods systematic and of a high

quality– Identified the reflex arc that became the framework

for psychology’s stimulus->response

Controversy

• Bell – an English neuroanatomist– Claimed he had discovered this first and published it

in a private publication– Demanded credit for the discovery or he claimed

“priority”– His description of the functions was wrong

• Ventral nerves voluntary movement• Dorsal nerves involuntary movement

– Magendie read Bell’s paper said it was similar but not enough to quit his claim of priority

Controversy (cont.)

• Final outcome was the Bell-Magendie Law• In reality, Bell had no claim to the finding

– Magendie used better experimental methods– Magendie findings more complete and definitive– His conclusions were clear and correct– Much of Bell’s criticisms were inaccurate and

unrelated to the issue– There was extensive evidence that Bell alstered his

early work to support his claim

Bell’s contribution

• After Magendie published his paper, Bell made his most significant contributiions– Since nerves intervene between the world and

our perceptions, nerve activity can influence the quality of our perceptions

– The sensation a person experiences depends upon not only the stimulus but upon which nerve was active

Muller and the doctrine of Nerve Specificity

• 5 kinds of nerves one for each sensory ability. Each carried only one type of sensory information

• Failure of Muller – – Attempted to measure the speed of nerve conduction

and was unable to do so because inadequate measuring devices

– Concluded that nerve impulses were instantaneous and therefore could not be measured

Muller and “vitalism”

• Vitalism –Life processes could not be explained by the interaction of physical and chemical processes alone. Life was more than a physical process and could not be reduced to physical processes. Therefore there is a life force that was beyond scientific study

Herman von Helmholtz

• Rejected vitalism – nothing mysterious about life; it could be studied using physical and chemical methods of inquiry – the same laws that apply to nonliving things apply to living things– Example Principle of Conservation of Energy

Contributions of von Helmholtz

• He developed equipment that could measure nerve impulses – they were not instantaneous – activity of nervous system could be studied. Motor neuron in frog had impulses of 43 meters/second

• Speed of nerve conduction in humans much slower than previously thought and could be measured

• Importance to development of psychology – mental actions could be measured and studied

Important example

• F.C. Donders – Dutch physiologist described 3 types of reaction times– A-reaction time – simple s->r– B-reaction time – see many stimuli (one at a time)

make a discrimination - choose the correct response to make

– C-reaction time – see many stimuli respond only to1 of the stimuli

• Each of these reaction times could be measured and used to calculate the speed of mental processing

Example (cont.)

• Measure A-reaction time:– Bell -> Push button

• Measure B-reaction time:– Bell or light presented; press red button for bell or press blue

button if light present• Measure C-reaction time:

– Bell or light presented; press button if bell rung• Subtract A from B to determine time needed to make

discrimination between two stimuli• Subtract C from B to determine time needed to

determine the correct response

Von Helmholtz – Theory of Perception

• Sensations are the raw elements of conscious experience; they result from physical activity of different sensory organs

• Perceptions are sensations converted by past experience – past experiences give meaning to sensations by turning them into perceptions

• Theory of color vision – Young-Helmholtz Trichromatic Theory

Helmholtz’s major influence

• Psychological events could be studied using scientific methods

• Studying and measuring the relationship between physical events and mental experiences naturally led to experimental psychology

• Helmholtz was never a psychologist

Localization of Function

Franz Gall – Phrenology 1810-1819• A person’s personality characteristics could be

determined by the size of different bumps on the head

• Concept that physical features could indicate psychological characteristics very popular at the time– Darwin almost excluded from trip on HMS Beagle

because the Captain didn’t think his nose shape was that of a sailor

Gall’s error with Phrenology

• His assumption that the shape of the skull was related to the size of the underlying areas of brain

• His “faculties” of personality were arbitrary and undefendable

• Confirmation bias – only presented cases that were consistent with his theory and discounted evidence that contradicted it

Phrenology

• Quickly rejected and ridiculed by scientific community – extreme reaction fueled by Gall not one of the inner circle

• Rejected by Catholic Church and books banned

• Gall’s response was to go on speaking tour making money using an invalid theory

Ignored contributions of Gall

• Higher cognitive processes related to the cortex, the more cortex an animal had the higher its mental functions

• 1st to describe 2 forms of matter in CNS and what they consisted of

• 1st to identify the interconnections between the hemispheres as made up of nerve bundles

• 1st to describe the crossing over of nerve fibers in the spinal cord

Pierre Flouren’s Experiments 1820-1830’s

• Most serious challenge to Gall and phrenology• Criticized Gall for improper methology• Experiments removed slices of brain from live animals,

then measured behavioral changes• Gall centered sex drive in an area now know as the

cerebellum in the back of the brain• Flouren showed that removal of this area affected motor

activity and coordination• Removed other areas and found different results than

predicted by phrenology

Debate

• Gall criticized Flourens studies by saying Flouren had removed extremely large amounts of tissue and had removed multiple areas resulting in extensive damage

• Finding Gall couldn’t respond to – recovery of function; sometimes animals regained a lost function

Flouren’s error

• The very large size of his lesions and his adamant rejection of phrenology led him to reject localization of functioning in the cortex

• The only localization of function was the cortex was the “seat of will” and the cerebellum was involved in muscle coordination

• Adopted unity of function

Phrenology, Mesmerism, Perkinism, and Acupuncture

• Popularity of phrenology continued in the general public despite scientific rejection

• Mesmerism, Perkinism, and acupuncture were summarily ejected, and disappeared

• Phrenology consistent with popular beliefs –physical characteristics could indicate personality traits; others were not

• Issue not addressed – if these were useless cures, why did they sometimes work?

Unrecognized contributions of Phrenology

• 1st systematic scientific attempt at behavior research

• 1st attempt at applied psychology

• 1st attempt at physiological psychology

The end of unity of function

• Famous case of Phineas Gage

• Studies of Pierre-Paul Broca– French physician and strong supporter of

Flouren’s unity of function

Broca’s change of mind

• 1861 Ernest Aubertin presented a single case study of a person who had lost his speech and had increasing right side paralysis. He predicted that damage in the frontal lobes would be found.

• April 4, 1861 - Broca argued against this idea of localization o speech

• A few days later Broca given a similar case

Case history

• Patient normal until loss of speech• 10 years later – weakness in right arm developed into

paralysis• 4 years later – paralysis spread down right side until he

could no longer stand• 7 years later bed ridden with loss of sensation on right

side – intellect intact• Patient died April 17, 1861• Autopsy showed large lesion centered in lower area of

left frontal lobe

Broca’s Area?

• Broca admitted he was wrong and continued to study the rain and case history

• He determined that the center of the lesion must be where speech was located– That was where the most damage was so it was where the

lesion began– The patient’s 1st deficit was a lack of speech

• Auberton not interested in studying the brain after he was shown to be correct

• Broca found the precise area involved in speech production

Localization of function (cont.)

• 1874 – Wernicke reported that an area of the temporal lobe was responsible for language comprehension

• 1860-1870’s – great use of lesion work with nonhumans to further localize function in the cortex

• 1870’s – began electrical stimulation of nonhuman animal brains

Electrical stimulation• Most important was the work of David Ferrier• 1876 – reported localization of different sensory

and motor functions in many nonhuman animals• Later, he so precisely mapped functions in the

monkey that his maps were used to remove a tumor in a human for the 1st time in history

• Bartholomew – 1874 – reported results of electrical stimulation of a human brain– Raised ethical questions and he was run out of town

Electrical stimulation

• Electrical stimulation continues today in both nonhumans and humans

• In humans, it is done during neurosurgery to locate functional areas because there tends to be large individual differences

Important point in history for psychology

• 1870’s • Philosophers have developed the general questions

psychologists will address• Studies of the nervous system, psychophysics,

physiology, etc. have applied the scientific method to the study of mental function

• They have also shown that we can measure mental processes.

• Finding that different mental processes involve different parts of the brain indicates they function differently