Ch. 8 Physiology and Psychophysics Flashcards
What was the basis for nerve transmission knowledge going into the modern era?
Bell-Magendie law. Both found a “law of forward direction” regarding the nervous system. Sensory nerves go from receptors to brain and motor neurons from brain to muscles/glands. Showed separate sensory/motor tracts in the spinal cord.
Muller
Doctrine of specific nerve energies
- There are different types of nerves specific to a type of sensation. ex. optic nerves always give an optical sensation, even when stimulated by a blow to the head or light to the eye.
Adequate stimulation
- each type of sense organ is more sensitive to a certain stimulus. ex. eye for light, ear for sound. Its a more adequate stimulus. (he thought the nerve type was the determinant and not the brain location. He was wrong- its the brain location)
How is Muller’s findings on nerve transmission related to Kant?
Muller was Kantian. He figured that his idea of “adequate stimulation” was a physiological version of Kant’s idea of “innate categories of thought”. Rather than mental processes it was a physiological process that determines/interprets the world into what we see. We do not see the real world
Muller figured he had found Kant’s nativistic “innate categories of thought” (sense info is translated by innate categories of thought before we become conscious of it)
Muller’s system was not rationalistic like Kant’s- it was physiological. He was a fan of Kant and still found room for rationalism: believed in a mind capable of attending to some info and excluding others.
End result is the same: we don’t see the world as it is. We see it as an interpretation of a physiological process (nerves, brain, sensory organs)
Who is the most important thinker in this chapter who some consider the biggest scientist of the 19th century?
Name his important findings
Helmholtz. (was a mechanistic-materialist and against vitalism)
A. Principle of conservation of energy applied to organisms
- Frog experiment. Applied the already established principle to organisms by measuring oxygen and food consumption with energy expenditure.
B. Rate of nerve conduction
- Vitalists thought that non-material forces governed behavior. Instead, Helmholtz stimulated a frog nerve at varying lengths away from the muscle and noted response time. Used this to calculate the speed of nerve transmission.(90ft/second). Did it to humans by stimulating high and low leg and asking them to press a button. (165-330ft/second)
NOTE- early reaction time studies proven wrong and were abandoned due to poor repeatibility. Different scores across and within subjects to same test. Still important.
Trichromatic theory of vision(Young-Helmholtz theory), resonance place theory of auditory perception
TRRP
Describe Helmholtz’ theory of perception
Which thinker inspired him?
Materialist (physiological apparatus provides the mechanism for sensation) PLUS unconscious inference (sensations and perceptions)
Sensation (raw)—–unconscious inference = perception
Past experience is what turns a sensation into a perception.
Sensations: raw elements of conscious experience from the physiological apparatus
Perceptions: sensations after interpretation by past experiences
Helmholtz was a good Kantian: he saw perception through a Kantian lens. (Kant’s innate categories of thought interpret raw data into perception. ie. we do not experience the world directly it goes through a filter)
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Helmholtz saw psych as an experimental science
F.
Did not see himself as a psychologist. Too metaphysical, we was a mechanistic-materialist. Still, he had room for unconscious inference in his theory of perception
Describe Helmholtz’ theory of vision and auditory perception
Trichromatic theory of vision (Young-Helmholtz theory)
- Newton found that the actual wavelength of light doesn’t always correspond to what we see. We see certain different wavelengths as the same color.
Helmholtz used Muller’s theory of specific nerve energies to postulate we have 3 types of receptor in the retina for the primary colors. We see in combination of those and we see all 3 as white. Color-blindness was a lack of one receptor type.
Auditory perception (sympathetic vibration)
- Again used Muller’s specific nerve energies. Basilar membrane has thousands of types of nerve fibers: Longer for lower frequency and shorter for higher. (tuning fork and piano sound of same frequency causes the same nerves to vibrate)
T or F
Helmholtz was a materialist-empiricist who believed that the environment caused sensations and perception which are interpreted mechanistically through sensory apparatus of the organism. He shared the passive mind concept with the empiricists
F
Helmholtz followed the German zeitgeist of an active mind.
Sensations came from the sensory apparatus and accorded to materialistic principles. However, an active mind interprets those raw sensations using past experience. This gives us perception. (Sensation and perception)
How did Helmholtz study nerve transmission?
Studied speed of nerve transmission
- Frog muscle with nerve. Stimulated nerve at various distances from the muscle and recorded time to movement
- Got humans to press a button when stimulated high or low on the leg. (lots of variation. Reaction time not a good way to study this)
Showed that physical/chemical processes (materialist) are responsible not nativist.
Upon what core idea re. perception did Kant and Helmholtz agree? What is the difference between the two views?
What experiment did Helmholtz use to confirm his view?
We do not experience the world directly. We perceive through a filter.
Kants filter is innate faculties of the mind “innate categories of thought”
Helmholtz’ filter is past experience “unconscious inference”.
(He actually took several of Kant’s innate categories of thought and showed how they were actually due to experience)
Experiment:
- Helmholtz put glasses on subjects that shifter their visual field several inches. The subjects would make errors, then adapt within minutes. When removing the glasses they would again make errors and adapt.
(Also looked at people who were born blind and got vision- it takes time to learn to make sense of vision)
What would Helmholtz say if you asked him how we perceive an object as moving and also how we see depth perception of an object being far away?
Moving: we have experience of witnessing events that create a series of images across the retina.
Depth: we learn from experience that the bigger the image in the retina the closer it is
What is the Helmholtz-Herring debate? Who was right
What else did Herring challenge? What is the current view on this challenge?
Helmholtz believed we perceived depth as we learn to correlate raw sensory data and experiences.
Herring believed that each point on the retina, when stimulated, provide 3 things: height, left-right orientation, depth.
- Herring also challenged the Young-Helmholtz/trichromatic theory of vision
- certain pairs of colors mixed give the perception of grey
- staring at red and looking away gives a green afterimage. Blue gives a yellow one.
- Color-blind folks lose red and green typically
Herring proposed 3 types of receptors on the retina that could each respond in 2 ways. (p.224) RG, YB, BW
- Current view: trichromatic is correct (retinal cells sensitive to RGB) but neural processes exist that are more like Herring’s proposal. (explains the faults in trichromatic theory)
What was Ladd-Franklin famous for?
Woman. Studied with Helmholtz learned his theory of color vision.
Evolution of the eye (based on evolutionary theory)
- achromatic vision came first and color vision came later
- fovea is most highly evolved part of the eye. Gives best detail and color sensitivity in lighted conditions. Retina’s periphery is better for low-light and movement.
Fovea has more cones and periphera has more rods
Stages of evolution of the eye
1. Achromatic
2. BY
3. RG
- RG is the last to evolve, explains higher rates of RG color blindness.
What is webers law?
For each sense modality there is a constant fraction of JND
Psychs first quantitative law, first statement about correspondence between physical and psychological reality
