PSY 497 Lecture Notes II

8/7/2019 PSY 497 Lecture Notes II

1/6

Mechanism

y In explaining his reasoning, Descartes proposed that the entire physical world and universe islike one big, orderly machine.

y This effectively discards the animistic view of the physical world, replacing it with a mechanisticone.

o Descartes reasoning: God created a self-perpetuating machine (the universe) so that Hewould not have to continually look after it.

o He endowed humans with reason so we could look after things for Him. So were Gods ground crew.

Descartes Legacy

y Descartes was noble in attempting to stop the conflict between religion and science by assigningeach a domain to study.

o Religion: the soul/mindo Science: the body (plus the rest of the physical world)

y One major question emerged in response to dualism:o If the soul/mind is completely separate from the body, how can it steer the

mechanism?

o Descartes proposed that this was somehow accomplished via the pineal gland, but thatdidnt wash.

y End result: The scientific community adopted the mechanistic component of Descartes modelwhile essentially disregarding the rest of it.

Laws of Physics

y A few decades after Descartes, Isaac Newton essentially founded the discipline of physics w/ the1687 publication of his book, The Mathematical Principles of Natural Philosophy.

y Increasingly, scholars had argued that the world was knowable and measurable, but no one hadreally been able to actually do it.

y By proposing the first few laws of physics and more importantly the mathematical equationsto be able to verify them, Newton not only proved the scientists right but gave them the

beginnings of the one tool they needed most

y Statistics!Empiricism

y The next development was the emergence of the empirical s school of thought in Britain, mostnotably John Locke ofScotland.

y Locke and his colleagues maintained that allhuman knowledge is acquired through sensationand perception.

y Locke proposed a new metaphor for the human mindo Tabula rasa, or scratched tablet


2/6

Each mind is essentially blank at birth. As we grow, our perceptions andexperiences begin to write on it.

Reasoning

y Perhaps the most important contribution of empiricism is its de-emphasis of deductivereasoning and increased emphasis on inductive reasoning.

o Deduction following rules of logic to discern smaller truths from larger ones.o Induction deriving general conclusions on the basis of specific observations (larger

truths from smaller ones).

y The counter-argument?o Human observation is both limited and flawed, sometimes deeply so.o After all, the earth looks flat, right?

Two main responses to the counter-argument

y 1. Experimentationo Use existing knowledge and deductive reasoning to derive a hypothesis.o Design and conduct a controlled study to test the hypothesis. Repeat as needed.o If results are repeatedly inconsistent with the hypothesis, the problem isnt because of

the limits of human observation. The problem is that the hypothesis isnt true.

o Up to this point, findings that were discrepant with the prevailing wisdom were markeddown (by most everyone) as simply exceptions to the rule rather than recognized as

evidence that the rule was incorrect.

y 2. If limited, flawed observation is whats holding us back, lets invent better equipment to helpus compensate for our perceptual deficiencies.

o Look what the telescope did for astronomy (and later, what the microscope did forchemistry and medicine).

The Enlightenment and the Industrial Revolution

y Four developments in the 18th and 19th centuries set the stage for the creation of Psychology:o 1. Darwins theory of evolutiono 2. Increased interest in human physiologyo 3. Research on nerve transmissiono 4. Development of statistics

Evolution

y In 1735, Swedish physician Carolus Linnaeus published his first volume of the classification ofplants, called System of Nature.

o It was 11 pages long.o By the time he published his final edition 35 years later it totaled 3000 pages.


3/6

y Scholars everywhere marveled at the incredible degree of diversity of flora throughout theknown world.

y The common question among them?...Evolution

y How did there come to be so many varieties?y In 1787, a large fossil was found just across the river from Philadelphia. It did not match any

known animal.

y This led geologists to begin looking for other fossils.y Linnaeus taxonomy of plants, coupled with the discovery of fossils, led to two related

questions:

o 1. How did we come to have such a diversity ofanimallife?o 2. Why do some species thrive while others become extinct?

y Several observations from the floral taxonomy research influenced Darwin:o Plants seem to prefer avoiding self-pollination even though they are quite capable of it.o Offspring of self-pollinators tend to be less healthy than those of cross-pollinators.o Cross-pollination produces more variation in the offspring.o Those variations are often healthier.o Variations sometimes produce new kinds of flora.

y In 1798, British economist Tom Malthus published An Essay on the Principles of Population.o Malthus projected that if humans did not exhibit greater procreative restraint they

would eventually surpass their ability to produce sufficient food.

o This would inevitably result in famine and/or war.y Together, the research on floral pollination and the warning by Malthus led Darwin to deduce

that a world oflimited resources necessarily results in competition for those resources, and onlythose best equipped to do so would survive

y The principle ofnatural selectiono Some genetic variants or mutations randomly result in a particular organism being

better suited to the environment it happens to be born into.

Getting foody Ex: A bird with an extra-hard beak born at a time of drought

Avoiding predatorsy Ex: turtles born with a harder shell avoid being eaten.

o Random variants such as these help those particular organisms survive and thereforepass on their genes to a subsequent generation.

Human Physiology

y The basic argument here:o If Newton could summarize how the entire universe works in just a few basic laws and

mathematical equations, surely we mustbe able to describe basic human functioning as

well.


4/6

y Research on visual optics and nervous transmission throughout the 19th century.o In 1802, English physician Tom Young proposed the trichromatic theory of color vision.o In 1834, German physician Ernst Weber determined that the difference threshold is

proportional to the intensity of the stimulus (Webers Law).

o In 1860, German physicist Gustav Fechner demonstrated that the relationship is actuallylogarithmic.

o Studies such as these spawned the area of research known aspsychophysics, whichserved as perhaps the final step in the development of psychology as an independent

discipline.

Neurobiology

y At the same time, German physicist Hermann von Helmholtz, was measuring the speed ofnervous impulses in frog legs.

y By stimulating the leg at one spot then timing the activation of subsequent spots, he was able toestimate that the speed of a nerve signal (in a frog at least) was ~6

3mi/hr.

y In 1868, Dutch ophthalmologist FranciscusDonders applied a version of von Helmholtzs methodto measuring how quickly humans can perform mental tasks.

o Mental chronometry = using reaction times to measure how long it takes a human toperform a cognitive task.

Statistics

y One critical difference between physic s and psychology is what makes psychological researchmuch more difficult to measure.

o Physical processes almost always yield the exact same numerical result.o Psychological processes, however, almost always yield at least somewhat different

numerical results. Why?

Too many factors to control, resulting in a lot of error What do we mean by error here?

y Not just measurement mistakes, but also biases, confounding variables,individual differences, etc.

o Because psychological measurement is inherently variable by its nature unlike laws ofphysics, humans are not all the same you cant get rid of error by just improving the

accuracy of the measurements.

o Somehow, the various sources of error must be taken into account. But how?y As B&R state in the text:

o In physics, good research requires extremely accurate measurements of a fewobservations.

o In psychology, good research requires a sufficiently large numberof observations, sothat the inherent noise in the data can be partialled out.

y In 1835, the Belgian mathematician AdolpheQuetlet was analyzing crime statistics in variouscountries.


5/6

o Unable to predict a single crime. Howevero Able to predict number of crimes in a given year, as well as the size of effect that certain

variables (gender, time of year, etc.) would have on the number. Why?

y Level of analysiso Predicting aggregate behavior is much easier than predicting individual behavior.

Another great quote from the text by 19th century American actuarialmathematician Elizur Wright:

y While nothing is more uncertain that the duration of a single life,nothing is more certain than the average duration of a thousand lives.

o Individual events may not be predictable, but averages are.o Across large samples, people are people. Individuals are not at all the same, but people

are people.

y Ronald Fischer invented the analysis of variance.CHAPTER3

The Debate Continues

y The debate ofRationalism vs. Empiricism continued through the advent of Psychology as adiscipline distinct from Philosophy.

y German philosopher Christian Wolff promoted the Cartesian notion of dualism by publishingtwo books in the 1730s, one of rational psychology and the other on empirical psychology.

y In the 1850s, Scottish philosopher Alexander Bain also published two books in an attempt tobridge the gap. His proposed explanation?

o AssociationismAssociationism

y Associationism = All human knowledge is acquired by perceptually noticing that two elements inthe world go together. Sound like anything familiar?

o Classical conditioning and operant conditioning. Classical recognizing that two stimuli go together

y Bain proposed the two principles of similarity and contiguity, each of which we still rely ontoday.

y In fact, simple associations would continue to be fundamental to most theories of psychologyfor over a century.

The Cradle of Psychology

y In 1870, Napoleon and the French defeated Prussia in the Franco-Prussian war.y This so humiliated Prussia (modern-day Germany) that they decided to modernize their country,

starting by reorganizing their entire school system.

y They chose to emphasize the importance of scientific research.


6/6

y In less than 30 years, Germany was at the front of major developments in all areas of science,including the birth of psychology.

Methods of Physiology

y In 1873, Wilhelm Wundt published one of the first textbooks on how to do psychology: ThePrinciples of Physiological Psychology

y Unlike most of his text author-predecessors, Wundt began acting on his book after publishing it.y Not only was Wundt the first to propose a specific method of studying psychology scientifically,

he also put together the first laboratory of what could legitimately be called psychology.

y U of Leipzig in 1879 IMPORTANTThe Leipzig Institute

y Probably the main reason why Wundts lab at Leipzig is universally considered the first is that italmost immediately became an institute.

o Institute = a university unit devoted to advanced instruction in a specific area.y Scholars and researchers from many countries including a substantial contingent from theU.S.

attended seminars, classes, and workshops that would last from a few days to several months.

y They received extensive instruction in the method of physiological psychology, and oftenreturned home to begin labs of their own.

Documents

PSY 497 Lecture Notes II