Lecture 1 Flashcards
Diagram from Descartes’ Treatise of Man
- Shows the formation of inverted retinal images in the eyes, and the transmission of these images, via the nerves so as to form a single, re-inverted image (an idea) on the surface of the pineal gland.
Rene Descartes
1596-1650
Defender of Dualism.
Invented the Cartesian coordinate system (X, Y, & Z).
Father of modern philosophy.
“I think therefore I am”
The Allegory of the Cave
~380 BCE
Plato’s (429-348 BCE) Early Philosophy of Perception
A Socratic Dialogue written by Plato that involved a conversation between Socrates and Glaucon, Plato’s brother.
Morpheus’s answer to Neo in The Matrix, 1999
“What is real? How do you define real? If you’re talking about what you can feel, what you can smell, what you can taste and see, then real is simply electrical signals interpreted by your brain. This is the world that you know.”
Perception and your sense of reality are the products of evolution:
Sensory systems provide a survival advantage.
Importance of type of energy in the environment for an animal determines which senses have developed.
Human senses are limited to only certain kinds of energy in the environment.
Therefore, humans’ sense of reality is also limited.
Carl Sagan Video
Cosmos- The 4th Dimension
Key concepts
- Dimensionality
- Projections to smaller dimensions
- Experiencing larger dimensions
http://www.youtube.com/watch?v=UnURElCzGc0
The 3 basic problems of perception
What is the quantitative relationship between physical energy and sensation?
(psychophysics)
How does physical energy in the environment become transduced into neural signals within the brain?
(sensory physiology)
How are patterns of sensory stimulation interpreted as meaningful events?
(psychophysiology)
What is the quantitative relationship between physical energy and sensation?
psychophysics
How does physical energy in the environment become transduced into neural signals within the brain?
sensory physiology
How are patterns of sensory stimulation interpreted as meaningful events?
psychophysiology
psychophysics
What is the quantitative relationship between physical energy and sensation?
sensory physiology
How does physical energy in the environment become transduced into neural signals within the brain?
psychophysiology
How are patterns of sensory stimulation interpreted as meaningful events?
Dualism
The idea that the mind has an existence separate from the material world.
Mental phenomena are non-physical.
Father of modern philosophy
Rene Descartes
Materialism
The idea that only matter and energy exist.
The mind is not separate from the body.
Most psychologists are modern materialists.
Gustav Fechner:
Personal Details
Held a Medical degree.
Worked to exhaustion.
Depression.
Spent 3 years alone.
Went blind looking at the sun.
Experience a “miracle” when vision returned.
Struggled with mind-body concepts.
Had some crazy ideas.
Believed in panpsychism:
The idea that all matter has consciousness.
Wrote Nanna, or Concerning the Mental Life of Plants
Gustav Fechner
1801–1887
Invented “psychophysics” and is often considered to be the true founder of Experimental Psychology.
Struggled with the mind/body problem.
Psychophysics:
Alternate Definition
The science of defining quantitative relationships between physical and psychological (subjective) events.
Ernst Weber
1795–1878
Discovered that the smallest change in a stimulus, such as the weight of an object, that can be detected is a constant proportion of the stimulus level,
(i.e. a linear relationship).
These proportions were called Weber Fractions.
Example: Object 1 must weigh 1/40th more/less than Object 2 for the difference to be noticeable or a JND (just-noticeable difference)
Just-Noticeable Difference
An Example of a Weber Fraction.
Object 1 must weigh 1/40th more/less than Object 2 for the difference to be noticeable or a JND (just-noticeable difference).
Fechner’s law
A principle describing the relationship between stimulus magnitude and the resulting sensation magnitude, such that the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity.
S = k log R
Example: 100 candles is 2x’s as bright as 10.
10 candles is 2x’s as bright as 1.
Stevens’ power law
- Proposed relationship between stimulus energy and perceived intensity is a power function.
Sensation = a(Intensity^b)
Chronological Summary of Laws
Weber’s Law:
As stimulus level increases or decreases, the magnitude of change must increase proportionately (linearly) to remain noticeable.
Fechner’s Law:
The magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity.
Steven’s Power Law:
Stimulus energy and perceived intensity is a power function.
Doctrine of specific nerve energies
A doctrine formulated by Johannes Müller (1801–1858) stating that the nature of a sensation depends on which sensory fibers are stimulated, not on how the fibers are stimulated.
Johannes Müller
1801–1858
Formulated the Doctrine of Specific Nerve Energies. a doctrine stating that the nature of a sensation depends on which sensory fibers are stimulated, not on how the fibers are stimulated
Photic Sneeze Reflex
Doctrine of specific nerve energies example
Photic Sneeze Reflex A.K.A., Sun Sneezing
18-35% of the population
2/3 of sun sneezers are female
Correlated with having a nasal septum deviation.
Amazingly the cause is still unknown
Caused by light intensity, not spectral composition
Most believe it is caused by “crossed wires”
Icy Hot
Doctrine of specific nerve energies example
Dulls the pain
2 Active Ingredients:
- Capsaicin- Found in chili peppers; Activates warmth fibers.
- Menthol- Activates cold fibers;
Menthol “cools”
Capsaicin “heats”
Sensation of both hot and cold
NO Actual Heat Transfer
List 2 Examples of the
Doctrine of Specific Nerve Energies
Photic Sneeze Reflex
Icy Hot
Hermann von Helmholtz
1821–1894.
First person to measure the Speed of Neural Impulses.
Demonstrated that Neurons Follow the Laws of Physics.
*Against what Müller believed.
Invented the Ophthalmoscope
Wrote On the Sensations of Tone (1863), one of the first studies of Auditory Perception.
Did A ton of other stuff for which there is not room to list.
Speed of neural transmission
~50-100 meters/second
Santiago Ramón y Cajal
1852–1934.
Discovered the direction of travel of nerve impulses.
Only ~1% of neurons absorb stain.
Improved upon a previous (Golgi’s) staining method and drawings.
Created incredibly detailed drawings of neurons and neural structure.
Ramón & Golgi were 1906 Nobel prize co-winners.
Santiago Ramón y Cajal
More details….
Cajal discovered the direction of travel of nerve impulses in the brain and spinal cord.
He was the first to note that information travels one way from the dendrites to the axon and not the reverse.
He postulated that neurons are discrete entities.
He was unhappy that, because Spanish was not used in the scientific community, his work was not read outside Spain.
Many so-called discoveries by English, German, and French scientists were actually rediscoveries of his work, which had been previously published in Spanish journals.
Good information on Cajal can be found on the Nobel prize website,
http://www.nobelprize.org/nobel_prizes/medicine/laureates/1906/cajal-bio.html
Vision
Electromagnetic
Electromagnetic Senses
Vision
Mechanical force Senses
Touch
Vestibular
(Sense of balance)
Audition
(Hearing)
Proprioception
(Sense of limb positions)
Chemical Diffusion Senses
Taste
Smell
Pain
Type of Energy:
Intense pressure or heat
