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Midterm

All midterm notes, includes lecture AND readings


Department
Psychology
Course Code
PSYB51H3
Professor
Matthias Niemeier
Study Guide
Midterm

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PSYB51 – PERCEPTION AND COGNITION
Midterm #1 Notes
Chapter 1 – Introduction
Early philosophy of perception
Plato's allegory of the cave
our reality is defined (restricted) by our senses
most of what we perceive depends on what changes, not what if constant
Heraclitus: you can never step into same river twice... everything is always changing
experiencing the first event changes the way we experience the same event a second time
perception also depends on qualities of the perceiver
our senses have evolved to match just the sorts of energy in environment that are most important for our
survival
things that move/ change draw our attn
adaptation: reduction in response caused by prior/ continuing stimulation ... perception quickly comes to
ignore anything that stays same for very long
Democritus: believed that sensations are caused by atoms leaving objects and making contact with our sense
organs
our senses should be trusted becuz perception is result of physical interaction b/w world and our bodies
primary qualities = directly perceived (weight + texture)
secondary qualities = requires interaction b/w atoms from objects and atoms in perceiver
sensory transducers = receptor that converts physical energy from environment into neural activity
perception is likley to depend more on experience than sensory reception does
Nativism
idea that the mind produces ideas that are not derived from external sources, that we have innate abilities that
are not learned
Plato believed in this, that body and mind are separate entities
Plato: truest sense of reality comes from ppl's mind and souls
Descartes: dualist, mind to be quite separate from the body
all true ideas must come from the mind, didn't trust his senses
monism: mind and matter are made up of/ reducible to a single ultimate substance
materialism: physical matter is the only reality
mentalism: mind is the true reality, objects exist only as aspects of mind's awareness (type of monism)
Empiricism
Hobbes: only matter exists
model of human nature relies entirely on experience
he thought memories were simply sensory experiences that were old and faded
and imagination is nothing but decaying sense
Locke: all thoughts ccould be constructed from experience with a collection of sensations
Fechner: inventor of psychophysics, true founder of experimental psychology
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Psychophysical methods (4)
absolute threshold: faintest amount of stimulation that can be detected
1. method of limits: stimuli is presented in order of increasing/ decreasing intensity varied incrementally
until participant responds diff
2. method of adjustment: participant is the one who steadily increases/ decreases intensity of stimulus
3. method of constant stimuli: many stimuli (ranging from rarely to almost always perceivable), presented
one at time, repeated, then scores are averaged,
4. magnitude estimation: participant assigns values according to perceived magnitudes of the stimuli
Signal Detection Theory
Stevens’ Power Law: A principle describing the relationship between stimulus magnitude and
resulting sensation magnitude, such that the magnitude of subjective sensation is proportional to the stimulus
magnitude raised to an exponent
S = aIb... S: sensation; I: stimulus intensity/magnitude; b: exponent; a: constant
psychophysical theory that quantifies the response of an observer to the presentation of a signal in the
presence of noise
cross-modality matching: ability to match intensities of sensations that come from diff sensory modalities
(matching sound with light)
what influences biases: costs of decisions, probability of events, personality
doctrine of specific nerve energies: Muller, nature of a sensation depends on which sensory fibers are
stimulated, not how they're stimulated
vitalism: believing that specialvital forces drive living organisms
Cranial nerves: Twelve pairs of nerves that originate in the brain stem and reach the periphery through
openings in the skull (roman numerals correspond to order of locations beginning from front of the skull)
– Olfactory (I) nerves (exclusive sensory info)
– Optic (II) nerves (exclusive sensory info)
– Oculomotor (III) nerves (moves the eyes)
– Trochlear (IV) nerve (moves the eyes)
– Abducens (VI) nerves (moves the eyes)
– Auditory (VIII) nerves (exclusive sensory info)
Helmholtz invented the ophthalmoscope.... to look at retina, blood vessels, receptors, neurons across back of
the eye
neural firing is actually electrochemical
Chapter 2 – Vision
light = A wave; a stream of photons, tiny particles that each consist of one quantum of energy
the shorter the wave length, the more powerful the wave is
light doesn't actually have a colour, it is our brain that assigns it
5 ways: absorbed, diffracted, reflected, transmitted, or refracted
wave
oscillation that travels through a medium
by transferring energy from one particle/
point to another w/o causing any
permanent desplacement of the medium
photon quantum of visible light or other form of
electromagnetic radiation demonstrating
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both particle and wave properties
Absorbed
Transduced/ taken up, not transmitted at
all
some light is lost if it passes through an
object (eg: dust)
if a surface is black, it'll absorb a lot of
light
if a surface is white, it'll reflect
filters abosrb light, we see the colour that
isn't absorbed
when light is absorbed, it is turned into
heat
Diffracted
Bent/ spread out (as they pass through a
narrow aperture)
1st reflection = Purkinjie reflections
ReflectedRedirect smth that strikes a surface,
usually back toward its point of origin
TransmittedEnergy that is passed on through a surface
Refracted
As light is transmitted (neither reflected/
absorbed), it can be refracted (altered by
another medium
part of an eye exam in which eye doctor
checks the patient's description is often
called a “refraction becuz doctor
determines how much light must be bent
by eyeglasses for it to be properly focused
on the retina
Refraction is necessary to focus light rays
and this is done by the lens
The Eye
human eye is somewhat similar to a camera
corneacornea doesn't contain any blood vessels
even tho it's a living tissue
most light photons are transmitted through
cornea
transparent cuz made of a highly ordered
arragnement of fibers
sclera protects our eye... front part of
sclera = cornea
nutrition to cornea comes from aqueous
humour (instead of blood vessels)
ciliary muscles stretch the lens... changes
degree of refraction
lens change degree of refraction so it is
focused into a single point on the retina,
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