Introduction to Sensation & Perception
Terms
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- Heraclitus
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540-480 BCE
Greek philosopher
Best know for: "You can never step into the same river twice" - Democritus
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480 - 370 BCE
Greek philosopher
Completely trusted senses
World is made of atoms that collide with one another - sensory transducer
- receptor that changes energy into neural energy
- Nativism
- Plato's idea that certain mental abilities must be innate
- Rene Descartes
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Only humans have minds
Had a dualist view (mind and body exist separately)
Even after death the mind survives
You cannot trust your senses
Cogito ergo sum (I think, therefore I am) - Monism
- The idea that mind and matter are made from the same thing
- Materialism
- A type of monism; idea that everything is matter
- Mentalism
- things only exist if the mind is aware of it
- Mind-Body dualism
- idea by Descartes that there are 2 separate principles in the world, spirit/soul and matter/body
- Thomas Hobbes
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Only matter exists
Rejected the idea of God and the idea of spirits
All knowledge comes from senses
Empiricism
Didn't believe in thinking/imagination - Empiricism
- the idea that experiences from the senses in the only source of knowledge
- John Locke
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British philosopher
A newborn mind is a tabula rasa, blank slate, written on by experiences - George Berkeley
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Irishman, philosopher
All knowledge comes from experience
Esse est percipi ("to be is to be perceived") - Gustav Fechner
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-German scientist-philosopher
-mathematically described the relationship between sensation(mind) and the energy that gave rise to that sensation - Panpsychism
- the idea that all matter has consciousness
- Fechner's law
- the principle describing the relationship between the physical magnitudes of stimuli and the perceived strength of the stimuli
- Ernst Weber
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-Anatomist and physiologist
-Used a device that allowed him to measure the distance between 2 points it took for a person to feel 2 points instead of one: called the two-point threshold
-The just noticeable difference (JND) or difference threshold is the smallest difference between 2 stimuli that can be correctly judged at different - Method of constant stimuli
- the process of exposing to different stimuli in order to find the lowest intensity that can be detected
- Method of Limits
- exposing to stimuli in order (in the case of tones) from the faintest sound to the loudest sound, and detecting the first tone heard.
- Method of adjustment
- when the subject adjusts the intensity of the stimuli (not usually used to find a threshold
- 2AFC (2 alternative forced choice)
- subject has to choose either left or right, or first or second time interval
- Signal detection theory
- means to quantify the ability to discern between signal and noise measured with the sensitive to the noise and criterion of theex observer.
- Olfactory (I)
- the first pair of cranial nerves that conduct impulses from the mucous through openings in the skull.
- Optic (II)
- comes from the retina and carry visual info to the thalamus and other parts of the brain
- Auditory (VIII)
- connects the inner ear with the brain, sending impulses concerned with hearing and balance.
- Oculomotor (III)
- supplies nerves to all the extrinsic muscles of the eye except the lateral rectus, and which supplies nerves to the elevator muscle of the upper eyelid, the ciliary muscle, and the sphincter.
- Trochlear (IV)
- supplies nerves to the superior oblique muscles of the eyeballs.
- Abducens (VI)
- Supply nerves to the lateral rectus muscle of each eye
- Johannes Muller
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-German physiologist
-Came up with the doctrine of specific nerve energies, stating that the nature of a sensation depends on which sensory fibers are stimulated, not on how. - Hermann von Helmholtz
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- believed that life forces are active in living organisms so that life cannot be explained solely by mechanism, vitalism.
-First to measure how fast neurons transmit their signals
-Invented the ophthalmoscope which allows you to look directly at the retina - Santiago Ramón y Cajal
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-Created a detailed drawing of a neuron and their connections
-Drawing suggested neurons don't touch and that they are separate cells with tiny gaps in between - Sir Charles Sherrington
- -Named the gap between the axon of one neuron and the dendrite of the next a synapse
- Otto Loewi
- -Knew that electrical waves did not cross synapses because some neurons increased while others decreased the response of the next neuron
- Sir Alan Hodkin (1914 - 1998) and Sir Andrew Huxley (1917-?)
- -Conducted experiments in where they isolated a single neuron and tested how the nerve impulse travels along the axon