1. Physiological Influences on Psychology
Chapter 3:
Physiological Influences on Psychology
Look for phys picts

2. The importance of the human observer
Measurement errors
1795: Maskelyne (England's royal astronomer) and his assistant, Kinnebrook, recorded different times for a star to travel from point to point
Measurement errors
1795: Maskelyne (England's royal astronomer) and his assistant, Kinnebrook, recorded different times for a star to travel from point to point
With “eye-and-ear” method, wire strung across viewing area of telescope, had to measure how long it took star to travel certain distance, used metronome, had to pay attention to the sound and the location of the star
Time difference? 5/10 of a second, Kinnebrook’s calculation slower
The more K tried to be careful, the more the difference increased
Fired

3. 20 years later… Bessel reviewed the above incident Why important?
Reasoned that the difference in times was due to individual differences not under personal control
Why important?
Cognitive processes occur over a definable time period
Scientists forced to acknowledge that the observer is important (personal traits and perceptions)
Scientists began to focus on the physiological processes involved in sensing and perceiving
Bessel reviewed the above incident
Reasoned that the difference in times was due to individual differences not under personal control
In other words, it might take two different people a different amount of time to switch their attention from one thing to another, or they might use different strategies for the task
When looked at other astronomers, found that it was actually common for there to be differences in measurements
Why important?
1. led to the general realization that perceptual and cognitive processes took a quantifiable time
2. Scientists forced to acknowledge that the observer is important (personal traits and perceptions)
So, scientists began to focus on the physiological processes involved in sensing and perceiving
previous to this, most early philosophers and British empiricists speculated about mental processes – via ideas like association – but they did not try to relate these processes to a physical foundation, ie, changes in the brain which caused mental processes
A few tried to speculate about physical causes, like Descartes with animal spirits moving thru hollow tubes, but people at time did not know very much about how the nervous system worked (not really possible until advances made in chemistry and physics)
The rest of what i will tell you today has to do with those discoveries that people made that helped us get an understanding of the nervous system and how it is related to cognitions

4. Early physiology Luigi Galvani (1737 – 1798)
Suggested that the nerve impulse is electrical
By mid 19th century accepted as fact
Luigi Galvani (1737 – 1798)
Suggested that the nerve impulse is electrical
(remember, descartes thought that it was tubes)
By mid 19th century accepted as fact, although still problem with ideas,
This was a purely reflexive system
Something from environment impacted sensory system, electrical pulse produced, routed through nervous system to make appropriate motor response

5. Early physiology Early 1800s:
Sensory and motor information travels in separate pathways
i.e., info is only sent in one direction
So, we knew that nerves existed, which could gain info and cause movement
And we knew nerves passed signals electrically,
And we knew that there might be something special about nerves, at least sensory nerves, that might make it possible for two different people to perceive something different
But we really did not understand how the whole system worked yet
In fact, we didn’t even know if sensory and motor info travelled through the same nerves or different nerves
In other words, transmission of info is usually one-way

6. Early physiology Johannes Muller (1801-1858)
Dominant advocate of experimental method
Specific energies of nerves doctrine
stimulation  specific nerve  sensation
Importance:
Lead to the idea that
different areas of the brain
have different functions
Localization of functions
Johannes Muller ( )
Dominant advocate of experimental method
Specific energies of nerves doctrine
stimulation  specific nerve  sensation
Importance:
Lead to the idea that different areas of the brain have different functions
Localization of functions

7. Research on the nervous system
Franz Josef Gall ( )
Phrenology
the correlation of bumps on the skull with personal traits
However, Flourens showed that underlying brain did not follow contours of skull
Gall: proposed that brain has many "organs", each one responsible for a given mental faculty. If faculty developed in individual, organ grows, pushes skull out
(popular from 1820 to 1850)

8. Research on brain functions
Pierre Flourens ( )
Extirpation: Lesion a given part of an animal’s brain and observe the resulting behavior changes.
Cerebrum: Higher mental processes:
Midbrain: Visual and auditory reflexes
Cerebellum: Coordination
Medulla: Heartbeat, respiration
Pierre Flourens ( )
Lesioned a given part of an animal’s brain and observed the resulting behavior changes.
Cerebrum: Higher mental processes:
Midbrain: Visual and auditory reflexes
Cerebellum: Coordination
Medulla: Heartbeat, respiration

9. Research on brain functions
Paul Broca ( )
Clinical method: examine damaged brain structures in humans after death
Broca’s area:
the speech center in the 3rd frontal convolution of the left hemisphere of the cerebral cortex
when damaged, person could not produce speech
Paul Broca ( )
Examined damaged brain structures in humans after death
Broca’s area:
the speech center in the 3rd frontal convolution of the left hemisphere of the cerebral cortex
when damaged, person could not produce speech

10. Research on brain functions
Electrical stimulation: pass a weak electrical current into animal’s brain to see motor responses
Electrical stimulation: pass a weak electrical current into animal’s brain to see motor responses

11. Research on the nervous system
Santiago Ramón y Cajal ( )
Discovered the direction of travel for brain and spinal cord nerve impulses (Nobel prize)
Nervous system comprised a vast array of independent, separate nerve cells.
Santiago Ramón y Cajal ( )
Discovered the direction of travel for brain and spinal cord nerve impulses (Nobel prize)
Nervous system comprised a vast array of independent, separate nerve cells.
(coincides with idea of mechanism)
All of this early research provided methods/tools to be used in psychological research
Philosophers were making it possible to study the mind (not just a religious entity now)
Future research would try to connect the physiology of perception with the psychology of perception

12. Importance of physiologists
Countered idea that psychology could never be a science …
by making it possible to measure mental experience …
with precise and elegant techniques of measurement.
In other words, they revealed a way to investigate the mind-body relationship
Countered idea that psychology could never be a science …
by making it possible to measure mental experience …
with precise and elegant techniques of measurement.
In other words, they revealed a way to investigate the mind-body relationship

13. The Beginnings of Experimental Psychology
Hermann von Helmholtz (1821– 1894)
Neural impulse
Vision
Audition
Studied physics, physiology and psychology – psychology not primary interest, but studies important for psychology
Thought of human sense organs as machines like the telegraph
Invented the ophthalmoscope (normal eye left, right eye with glaucoma – loose retinal ganglion cells)
Speed of Neural impulse – scientists assumed nerve impulse instant, or was too fast to measure
H. Stimulated motor nerve in leg of frog, waited for movement to get time it took for impulse to travel (90 ft per sec)
Also tried looking at humans from time of sensation to time of motor response – very variable, for both different people and same person
Vision – studied eye muscles and how lens is changed by other muscles
He also proposed a color perception theory
response pattern of the three different types of cone
Blue, green, and red are easy to understand, since they activate mostly their own color receptors, and a little bit of color next in sequence
Other colors, like yellow (lots red, some green, very little blue) and purple (lots of blue and red, little green) (additive color mixing with lights instead of pigments)
Audition – studied perception of timbre (ex. same note being played by different instruments, sound different despite their identity of pitch. )
Explanation: fundamental pitch, plus overtones (vibration rates more rapid than the fundamental tone)
Theory of hearing: theorized that part of inner ear, where hairs are present, vibrate to encode pitch (sort of like how one tuning fork can set another tuning fork into motion (called resonance)

14. The Beginnings of Experimental Psychology
Gustax Fechner (1801 – 1887)
Relative intensities
Absolute threshold
Differential threshold
Relative intensities – he had this idea on how to connect mind and body
Intensity of a stimulus was relative – give someone 1 mV of a shock, and then give them 2 mV; they should perceive twice the amount of pain, but they don’t their perception of pain is more than twice
Now he needed to test the idea, but how?
Would need to measure both the change in stimulus and the change in perception
Change iun stimulus easy enough, but perception required new method
Two ways to measure perception
Is stimulus present or not present – absolute threshold – smallest amount of energy needed to detect a stimulus
But people usually sensing things above this thresold, so another way…
Second, how much of a difference do I need there to be to detect a change in stimulus

15. method of limits
One way that he did this with
1. Method of limits
Stimuli of different intensities presented in ascending and descending order
Observer responds to whether she perceived the stimulus
Cross-over point (dashed lines) is the threshold - the average of the crossover values - is 98.5 in this experiment.

16. The Beginnings of Experimental Psychology
Ernst Weber (1795 – 1878)
Just Noticeable Differences No
100 lbs
101 lbs
Just noticeable differnce- smallest differences b/t two stimuli that is necessary for detection
DL / S = K
2/100 = .02
4/200 = .02
Yes
100 lbs
102 lbs

17. The Beginnings of Experimental Psychology
Ernst Weber (1795 – 1878)
Two-point thresholds:
Test in which two different points were stimulated on a person’s skin
The objective was to discover how far the two points had to be away from each for the person to notice that there were two points
First systematic experimental demonstration of the concept of threshold
Also demonstrated individual differences between people
One of main people who encourage experimentation
His findings helped sever ties of emerging psychology to philosophy
Two-point thresholds:
Test in which two different points were stimulated on a person’s skin
The objective was to discover how far the two points had to be away from each for the person to notice that there were two points
First systematic experimental demonstration of the concept of threshold
Also demonstrated individual differences between people

18. Many of these physiologists were German…
Why?
Location where physiology was firmly established
Tendency to use inductive rather than deductive reasoning
Temperament of German people
Broader definition of science
Greater opportunities to make a living as a scientist
Germany was the focus of pre-psychology physiology
Location: where physiology was firmly established; not so in France and England, where chemistry/physics were predominant
Inductive: going from observed facts to conclusion, by using generalizations (instead of reasoning from theory – deduction, used more in mathematics and physics)
Temperament: conscientious, meticulous  taxonomy
Broader Definition of science: included things like anthropology, history, linguistics, literary criticism as sciences, so less prejudiced (unlike England and France, who only willing to accept physics and chemistry)
Opportunities: more universities (more city-states – England had only 2 universities at the time, neither of which encouraged experimentation), more money to support professors and research, and climate at time in Germany encouraged academic freedom for both professors and students (didn’t have to follow a fixed curriculum – England didn’t want to add new fields to curriculum) (although competition intense, so professors that made it through the system were generally brilliant and very productive)

19. The formal founding of psychology
British empiricists
Subject matter: study mind and behavior
German physiologists
Methods: experimentation
General zeitgeist: encouraged melding of philosophy and physiology
British empiricists
Subject matter: study mind and behavior
German physiologists
Methods: experimentation
General zeitgeist: encouraged melding of philosophy and physiology