Class Notes (806,814)
Canada (492,451)
Psychology (6,022)
Mark Cole (10)

Lecture 4: 19th Century Science and Pseudoscience

8 Pages
Unlock Document

Western University
Psychology 3950F/G
Mark Cole

Lecture 4: 19 Century Science and Pseudoscience The Theory of Evolution Charles Darwin Early Life  Charles Darwin (1809-1882) was born in Shrewsbury, England  After primary school he went to Edinburgh to study medicine  But surgery without anaesthesis was appalling, not appealing  Next to Cambridge to prepare for ordination as an Anglican clergyman  He met John Henslow (botanist)  Henslow was unable to take up the post of naturalist on the Beagle  Darwin went instead and the rest is history The Voyage of the Beagle  Lasted 5 years and netted Darwin thousands of specimens, many of from the Galapagos  There he had noted deviations in animals, otherwise similar, when found on different islands (Darwin, 1845)  E.g., Finches who‟s beaks varied from long and thin, good for snatching insects from crevices, to short and fat, good for cracking seeds  Darwin notes the islands with long-beaked finches tended to have lots of insects hiding in crevices and those with short and thick beaks were devoid of such fauna but had lots of hard-to-crack seeds Home to England and The Origin of Species  Back home Darwin began to wonder if at one time all the ancestors of these finches were alike but had changed over generations due to natural selection o Religious explanation: God put finches with longer beaks in islands where there were lots of bugs and not many seeds and finches with shorter beaks on islands with less bugs and more seeds  Very different from the view of Jean-Baptiste Lamark (1744-1829) o Lamark argues that giraffes developed longer necks, even within their lifetimes, by stretching up to grasp high-up leaves, and then passed these longer necks on to their offspring o Driven by an inner “need” o Darwin did not believe that you could change your body in this way – depends on how you are born not on how you change your body throughout life  Darwin believed that the offspring of any species show variation and variations that aid survival tended to be passed on to offspring simply because the parents survive  Thus, unhelpful variations tend not to be passed on because the parents do not survive  Thus, the environment selects from among the variations that naturally occur in offspring  Darwin called this natural selection o Unnatural selection has being going on for centuries – deliberately crossbreeding animals for specific purposes (e.g., dog breeding)  Evolution if a passive phenomenon, whereas Lamark thought it was an active phenomenon Impact  The Origin of Species was published in 1859  Has made a massive impact on science – provided an alternative explanation for why animals are what they are  The Decent of Man (1877) – concerns evolution of humans o Humans are animals with many features similar to those in sub-human animals (e.g., circulatory systems)  E.g., the embryo of a human looks similar to the embryo of a dog o Animals also share characteristics with humans (e.g., loyalty, courage) o Basis of today‟s interest in animal cognition  The Expression of the Emotions in Man and Animals (1872) talks about the origins and survival value of emotional expression in both animals and humans o Just like long necks in giraffes would have a survival advantage, so would the ability to read expression in others o This kind of natural selection not limit to physical features, but could also influence more psychological features such as emotions  E.g., more intelligent individuals are more likely to survive and pass their intelligence to their offspring than less intelligent individuals  Darwin influenced Herbert Spencer (1820-1903), George Romanes (1848-1894), and Francis Dalton (1822-1911) o Spencer used „survival of the fittest‟ more so than Darwin – thought people would fend for themselves and compete with one another, causing those who are the strongest to make the most money Mental Measurement  British empiricist (knowledge derived from experience)  But, first measurement delayed to early to mid 19 century Weber‟s Life and Work  Ernst Heinrish Weber (1795-1878)  Born in Wittenberg, Germnay  PhD in Leipzig (1815)  Dozent in 1815  Professor of Anatomy (1818)  Professor of Physiology (1825)  Studied difference threshold (JND) o JND is a constant fraction of the standard within a modality o E.g., for actively lifted weights = 1/40 o Passive assessment  larger JND (1/30) o Two-point cutaneous threshold varies with body location  E.g., 1 mm on the finger top  E.g., 40-60 mm on the back Fechner‟s Early Life and Work  Gustav Theodor Fechner (1801-1887)  Born in Germany  M.D. (1817) at age 16  Professor of Physics (1834)  Invalided out in 1844, but remained another 44 years  Psychophysics outlines in The Things of Heaven and the Hereafter Psychophysics  Relationships between mind and body  Quantification was the solution to the mind-body problem  Specifically, the relationship between physical stimulation and mental sensation  Two assumptions: 1. Accepted constancy of JND, thus: I/I = K 2. All JNDs are equal (interval scale) o I.e., sensation could be measured using physical units (fundamental measurement) o Ratio scale if the limen is assumed to be zero JNDs   10 JNDs ought to be twice as intense as 5 JNDs o Not only is this scale an equal interval scale of JNDs, but also a ratio scale (scales that have a true zero) o Any change in S (not just the JND) represented a change in I o Thus: S = c I/I, where:  S is a change in sensation  I is a change in stimulation  c is a constant of proportionality (unique to each modality) (N.B., the relationship would be linear if c=1.0) o Integrated, using calculus: S = k log1(NB kc)  Where S is the magnitude of the sensation  logI is the log to base 10 of stimulus intensity  k is a constant related to the modality in question o Basically, arithmetic increases in S result from geometric increases in I  The physical stimulus I had to increase geometrically in order for the sensation to increase arithmetically o For example: I S (k=10) 10 10 20 13 40 16 80 19 20| 1.5| 18| X | 16| X | X 14| X | X 12| | X S 10| X Log S 1.0| X 8| | 6| | 4| | 2| | 0|_____________________ 0|_____________________ 50 100 1 2 I Log I  Modestly termed Weber’s Law  Should be at least Weber-Fechner Law  Only holds in medium and high range of stimulus intensity o When you got into lower values, the function no longer predicted accurately o The Weber fraction is only constant in the upper ranges  Assumption of ratio scale not correct (S.S. Stevens) o A sound 20 JNDs above threshold is much more than twice as loud as a sound 10 JNDs above threshold  Steven‟s Power Law: S = k In o Exponential increases in I  arithmetic increases in S o Produces the same negatively accelerated curve as Weber‟s Law I S (k=10) 20 | 1.0 10 18 | X 2.1 13 n=0.33 16 | X 4.2 16 k=10 14 | X 7.1 19 S 12 | 10 | X 8 | e.g., for brightness 6 | 2 | 0 |________________________ 1 2 3 4 5 6 7 8 I I S (k=10) 20 | X 1.0 10 18 | 1.11 13 n=0.25 16 | X 1.21 16 k=10 14 | 1.29 19 12 | X S 10 | X 8 | e.g., for shock intensity 6 | 2 |
More Less

Related notes for Psychology 3950F/G

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.