PSYB51H3 Lecture Notes - Not Fair, Empiricism, Power Law

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Published on 6 Jun 2012
PSYB51-Lecture 1
- Final exam will definitely have one short answer question lecture 11 and one from lecture
12, then one lecture question for first 5 lectures and then one question on second half
- Psychophysics grew from philosophy, early cornerstone of psychology which is very
important today(way of testing)
- Plato’s The Allegory of The Cave
o Our conception of reality is critically dependent on information gathered through
our senses, that is our reality(reality is based on what we are able to perceive)
o Pictured us as how we perceive the world, he claimed that we are like prisoners
born in a cave chained to a wall facing back wall, what we see are the shadows
projected onto the back wall created by objects carrying around behind your back,
the light itself is just from a fire burning
o You don’t know what’s outside of the cave because you are the prisoner of your
perception, Plato was very pessimistic
- Perception and your sense of reality are products of evolution, they came to existence to
serve certain purposes:
o Survival- plants don’t usually have behaviours, but fly traps show some sort of
behaviour upon some stimulation, the plant uses very primitive sensory-motor
mechanism that the plant developed to survive(even if the plant is limited in its
sensation it is okay because that is all it needs to survive)
o Importance of type of energy in environment determines which senses have
developed(ie colour is irrelevant to fly trap
Certain animals have senses we haven’t developed: Bees can see ultraviolet
light, snakes can sense infrared light developed for its environment and
diet, dogs can hear ultrasonic power, some birds have acute vision, chicken
etc. have 4 types of photoreceptors(better colour vision) also some can see
magnetic field
o i.e. we might not see the entire reality but we probably don’t need to worry too
much, because we have other senses
- We can sometimes develop certain types of senses we won’t have, Ben lost his eyes as a
toddler but had good ear so he learned echolocation
o Echolocation send out a sound and as it bounces off an obstacle what you hear in
the echo tells you what’s out there
- Plato:
o Perception depends on events on energy that change in the world
o Our understanding of reality is restricted to things that we can perceive
o Something forgotten? Depends on us, depends on what sort of sensory channels
we have
- Heraclitus: “You can never step into the same river twice”-if you step into the river, you
have changed in some way
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o Panta rhei: everything flows
o Idea that perceiver cannot perceive the same event in exactly the same manner
each time
Adaption- a reduction in response caused by prior or continuing
Change-our perceptual system is designed to pick up change than anything
- Adaption Demo 1: if you look long enough at the plus, and then the dot on baby picture
you don’t see the two colour differences of that picture. When you fixate at the picture on
left, the blue picture is fixated in the left visual field and the yellow colour is the right
visual field. So in the left visual field you get adapted to blue and right visual field gets
adapted to the warmer colour, so when you look at the baby’s picture your left visual field
the perception of blue is slightly reduced and your right visual field’s perception of the
warmer colour is slightly reduced so this counterbalances the discolouration of the baby
picture , simple form of adaption in early sensation level in retina
- Demo 2: 1 for male and female faces that are in competition with each other, so when you
look at one gender face, one group of neurons gets exhausted and the other one gets
stronger so the perception of the neutral face is biased in the opposite direction (ie if you
see the male face then the neutral face will look female)
- Demo 3: whether you say the rat or man biased your perception as to how you saw this
ambiguous picture(equal components of mouse and man); this is not adaption because
then it would work the opposite direction
- Democritus(460-370 BCE): The world is made of atoms that collide with one
another(came up with the idea of atoms, cannot be divide any further)
o Sensation are caused by atoms leavings objects and making contact with our sense
organs , clearly wrong for vision etc.(however, his idea was true for the sense of
smell, certain molecules peel off a rose for eg and travels through the air and that is
what you smell; also how taste works)
o He was confident that what we see is what we get
o Perception is the result of physical interaction between and world and our bodies
(sensory transduction)
Idea of primary qualities and secondary qualities(when you see something
it would be secondary quality because atoms are peeling off something and
entering eyes as opposed to touching something where you are directly
interacting with it)
(low level sensation vs. High level perception)- sensation is more of the
mechanistic aspect of how physical energy is transduced into neural signal,
perception is more cognitive, higher level, it is what we make out of
sensation, illusion will show us that they are not the same thing
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Sensory transducer: a receptor that converts physical energy from the
environment into neural activity, it’s true for every sense
- Nativism: the idea that the mind produces ideas that are not derived from external sources
We are just born with these ideas rather than learn through experience,
Plato was one of the first people to say this
Plate said truest sense of reality comes from people’s minds and souls, we
are born with it
- 2000 years later there was Descartes(1596-1650) dualist view of world: both mind and
body exist; intertwined with nativism and a bit with scientific point of view, mind is born
with these ideas, there are certain things we cannot know with experience
o Mind-body dualism: the idea positing the existence of two distinct principles of
being in the universe; spirit/soul and matter/body e.g. Descartes, Plato
o A problem with dualism is that if there is a mind that is independent of matter, then
it is hard to figure out how these two things interact with each other, how can the
non-physical mind interact with a physical body?
- A simpler explanation is the idea of monism: the idea that the mind and matter are formed
from or reducible to a single ultimate substance or principle of being
o Everything can be a thought(mentalism) or solilism(only I exist,
everything/everyone else is an illusion)
- Materialism: is another type of monism, the mind is somehow associated with the
material, electrochemical process of the brain; the idea that physical matter is only reality
and everything including the mind can be explained in terms of matter and physical
phenomena. Materialism is a type of monism.
o According to this idea there is no soul another problem occurs how can you know
things unless you experience them, thus empiricism claim this
- Empiricism: the idea that experience from the sense sis the only source of knowledge
o Hobbes believed that everything that could ever be known or even imagined had to
be learned through the senses, memory and imagery were just decayed form of
sensation according to him, everything is perception and nothing else
o Locke sought to explain how all thoughts, even complex one, could be constructed
from experience with a collection of sensations, tabula rasa(clean slate) as we
experience things we learn and understand things more
- Not everything can be learned as claimed by empiricists, nativist view can be explained
through genes, somebody else learned it or it came through mutation
o Nature vs. Nurture
- Fechner invented “psychophysics” thought to be the true founder of experimental
psychology, pioneering work relating changes in the physical world to changes in our
psychological experiences
o Came up with the idea of panpsychism: the idea that all mater has consciousness,
this motivated him to develop of psychophysics
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