PSC 1 Lecture Notes - Lecture 5: Thalamus, Ganglion Cell, David H. Hubel
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Lecture 5: Perception I
Sensation and perception
• RQ: How and why do people perceive the world the way they do?
o Hypothesis: humans perceive the environment with 100% accuracy.
• Perception process--> is NOT the exact copy of the environment.
• Because we have lots of experience, expectations, memories, biases etc. which
lead to perceiving the world in a unique way.
o Thus, perception processes do not yield a mental copy of the environment.
• People filter stimuli (attention)
▪ We focus only on the stuff that is useful at that moment and filter rest
out.
• We become aware of a tiny fraction.
o Analogy - perception is like cell phones
• Energy in the environment
• Cellphones only pick up part of that energy spectrum, thus neural processing.
• Distal and proximal stimuli:
▪
Cell phone
vision
Distal S.
Cell tower
Object in
environment
Proximal S.
Signal at phone
receiver.
Light at retina.
• Vision
o Energy = light
o Eyes focus light on the retina
o The retina transduces light into neural signals (action potentials)
• Taking in energy in one form and transforming into another form of energy
• Receptor cells, a form of neurons, that react when hit by a photon and then
generates neural energy.
• Start with light end up with neural energy, thus transducal.
o The brain interprets neural signals from the retina.
• Optics
o Light hits the objects and scatters
o Lenses bend light
• Take all the divergent light and focus it on one point.
o The eye focuses light (via cornea & lens)
o Myopia:
• glasses supplement the focus of light
• Shortsighted.
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• Concave lens is used
• A myopic person has clear vision when looking at objects close to them, but
distant objects will appear blurred. This is because light is focused in front of
the retina and, being too far forward in the eye, things in the distance look
blurred.
o Hyperopia:
• the image of a nearby object is formed behind the retina. This means that light
is focused too far back in the eye, causing things which are close up to appear
blurred.
• Longsighted
• Convex lens is used.
• Visual fields
Horses perceive the world differently than us as they have eyes on eithers ides of
their heads.
• They have monocular vison
• They have blind spots
• Most herbivores have this
Humans have binocular vison like other predators.
We have left visual field and right visual field
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