Physiological Influences on Psychology, Part IIWhere are we?The Beginnings of Experimental PsychologySlide 4Hermann Von Helmholz (1821-1894)Hermann von HelmholzContributions to PsychologyErnst Weber (1795-1878)Ernst WeberSlide 10Slide 11Gustav Theodore Fechner ((1801-1887)Gustav FechnerSlide 14Slide 15Slide 16Wilhelm WundtThe Formal Founding of PsychologyDiscussion QuestionsSlide 20Slide 21MONDAY, JANUARY 26TH 2015PHYSIOLOGICAL INFLUENCES ON PSYCHOLOGY, PART IIWHERE ARE WE?•This is important!•Philosophers = acquisition of knowledge through the senses•Astronomers = the senses seem to vary from person to person•Physiologists = first applied experimental methods for studying the senses and the nervous system•We’re talking about three of these scientists today!THE BEGINNINGS OF EXPERIMENTAL PSYCHOLOGY•They were all German…coincidence? NOPE•The Zeitgeist there was just right–Experimental physiology already had a strong foothold–The “German temperament” was dedicated to precise description and classification needed for advancement in other fields of natural science–Germans were inductive, whereas other countries like England and France were more deductive–More sciences were being studied in Germany, whereas England and France were more focused on physics and chemistryTHE BEGINNINGS OF EXPERIMENTAL PSYCHOLOGY•More about the German Zeitgeist–Germany had just been unified in 1870, so there were tons of universities around–German institutions were given freedom to teach whatever they wanted–England had Cambridge and Oxford, and they were not too keen on the study of psychology•Experimental psychology would “insult religion by putting the human soul on a pair of scales” (Hearnshaw, 1987, p. 125)–So you had to be rich and independent to have any freedom of study in England or France–Johns Hopkins, America’s first research university, wasn’t established till 1876 – Baltimore was called “a little fragment of Germany” –Overall, it was much easier to make a living as a researcher if you were living in GermanyHERMANN VON HELMHOLZ (1821-1894)•https://www.youtube.com/watch?v=lYtcza1fC1MHERMANN VON HELMHOLZ•Was trained to be an army surgeon and got free tuition!•Received worldwide recognition for his invention of the opthalmoscope, a device still used to examine the eye and diagnose disorders of the retina•Also a physicist and physiologist, so it’s no surprise that he was a huge mechanist who believed that humans functioned like machines•Formulated the law of conservation of energy – SUCH a physicist•Mostly studied sensory organs themselves, particularly ears and eyes•Died of a stroke after a fall at the Chicago World’s FairCONTRIBUTIONS TO PSYCHOLOGY•The speed of the neural impulse – it’s not instantaneous!–Discovered this with stimulation of nerves in the leg muscle of a frog and recorded the delay (90 feet per second - the importance of measurement!)–Lots of reaction time research is done in psychology•Experimented with the time between the stimulation of a sense organ and the resulting motor response – which happens to be highly variable across individuals•This was some of the first experimentation and measurement for psychophysiological processes, and his work on the function of the senses and nervous system were important for psychologyERNST WEBER (1795-1878)•https://www.youtube.com/watch?v=DEdTRw8B7PIERNST WEBER•A professor of anatomy and physiology from 1817 till his retirement in 1871•He was interested in sensory organs, mostly skin and muscular sensationCONTRIBUTIONS TO PSYCHOLOGY•Two-point threshold: the threshold at which two points of stimulation can be distinguished as such•This might not seem relevant to psychology, but this was the first experimental demonstration of the concept of threshold, a very popular topic in psychology for a number of mental and emotional phenomenaCONTRIBUTIONS TO PSYCHOLOGY•Just noticeable difference: the smallest difference between weights (literal ones) that could be detected–He found it to be 1:40 of the weights in question•Then he looked to see how muscle sensations might contribute to this difference–Subjects made much more accurate estimates when they had to lift the weights themselves (tactile + muscular) rather than being handed them (tactile alone)•He concluded that there is not a direct relationship between a physical stimulus and our perception of it; rather, the just noticeable difference is relative based on other factors•These findings provided a method for investigating the relationship between the stimulus and the resulting sensationGUSTAV THEODORE FECHNER ((1801-1887)•http://www.youtube.com/watch?v=nPEEuTID7fUGUSTAV FECHNER•Attended Weber’s lectures on physiology when he was in college•Challenged the mechanistic influence on medicine and science with his humanistic view and dabbled in lots of other fields•Was actually kind of crazy – was extremely depressed for many years following a severe eye injury while studying vision •After many years as an invalid and some crazy antics, he transitioned to euphoria and delusions of grandeurCONTRIBUTIONS TO PSYCHOLOGY•Concluded that the amount of sensation (a mental quality) depends on the amount of stimulation (the physical quality)–S = K log R (bells example)–I think Weber would have liked this!•What a great discovery about the relationship between the body and the mind! •To study this, he needed a way to measure subjective sensations–He proposed 2 ways to do this, the first is: absolute threshold and differential thresholdCONTRIBUTIONS TO PSYCHOLOGY•Absolute threshold: the point of sensitivity below which no sensations can be detected and above which sensations can be experienced – is there a stimulus and was it sensed?•If you have an absolute threshold, you can only detect those stimuli with the lowest intensity•Thus, Fechner proposed the differential threshold, which is the least amount of change in a stimulus that gives rise to a change in sensation•Basically the necessary amount of change for a just noticeable differenceCONTRIBUTIONS TO PSYCHOLOGY•Psychophysics: the scientific study of the relations between mental and material worlds•Used experimental methods including accounting for individual differences and self-report measures•In this way, he was scientifically measuring and testing psychological processesWILHELM WUNDT•Inspired by
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