How do we see the world
Structuralism
One of the first schools of thought
Perceptions like a camera view of the world, views as a mosaic
our perceptions are the sum of sensations produced by each element of the mosaic
“The ‘taste’ of lemonade is made up of a sweet taste, an acid taste, a scent (the fragrance of lemon), a sensation of temperature and a pricking (cutaneous) sensation” - Tichener 1901
Titchener
spread strucuralism
fostered one of the largest PhD programmes in the US
Key elements of analysis are sensations
every experience is a collection of each sensation
different aspects
intensity
extent
duration
Investigated with introspection
Wundt
Visual perception
like a passive camera
images from the world are painted in our eyes to give rise to sensations
1896 psych
Had their own psych flavoured periodic table
about 44,000 different qualifications of consciousness
Issues
Introspection is flawed
not easily quantified
not able to observate from an objective measure
disagreement between psychologists as to what sensations to include
Questioned by Gestadlt psychology
Gestalt theory
perception is NOT a mosaic- the whole is more than just the sum of all its parts, context is critical to perception
Perceptual experiences are dynamic and organised by laws that govern the perceptual systems
Visual perceptions are more than direct registration of sensations, they're about perceptual constancies
Colour perceptions
colours can seeem to be different to what they actually are depending on what colours their surroudnings are
this shows that context is important to perceiving colour
not just about relaying the wavelength from the isolated colours into our retinas
context effects
therfore perception is more than just a sum of sensations and context is important, which is what can lead to illusions
Muller-Lyer illusion
T illusion
you perceive size and shape as differently when affected by orientation and context
perceptual systems also routine impose structures onto the things we see
certain parts can seem more salient than others
Bistability
Closure
Similarity
Goodness
2 stable states
e.g FedEx arrow
amolar edge
(not actually there)
when things look similar we tend to group them together
an attempt to capture all organizational principles with one physical law
lots of natural phenomena leas to this effect
Psychophysical isomorphism
organises incoming information
Isomorphism hypothesis: perceptual organization phenomena reflect similar organization laws of neural networks in our brain
2 groups of neurons
one works to see the one part of the illusion, the other works to see the other
when one group gets tired the other takes over
states that a conscious experience is structurally identical to the activity of the brain.
This means that the isomorphism is between the perception of a stimulus and brain activity, not between the physical stimulus and the brain activity itself.
examples
colour constancy
form constancy
objects in different coloured lighting are not perceived as changing colours even thought the colour of the light that hits the eyes changes
objects are not perceived as changing shape every time they change orientation despite the shape of the image painting (on our eyes) being different
issues
use of non ecological stimuli
nativism
grouping principles are innate properties of our brain? if so then what about learning? what;s the point of that?
we see things the way we do because our brain is wired that way? that's not reaaaally an explanation, it's more just saying "hey this is it shush now"
interesting demonstrations but poor quantification of any phenomena
Functionalism
The mind cannot be studied in isolation, without taking into account the environment
The function of the mind is to determine the best course of action that is likely to improve the state of the organism
The purpose of perception is to increase the survival chances of an organism
The function of colour perception
- must be important for survival
- colour borders; defeating camouflage
- both food finding and evading predators
- identifying objects with similar luminance and shapes
- reading emotions and health cues
Brunswik's probabilistic functionalism
created the term ecological validity
- set up first psych lab in turkey
objects usually produce a cluster of cues
cues produces by objects in the world are unreliable
the key problem of perception is to figure out (infer) which objects produced what cue
to survive organisms must be able to to make these inferences
perceiver as an intuitive statitician
many cues need to be combined and properly wighed
ecological vailidty
e.g., small retinal images tend to be produced by small objects, but not always
how reliable a cue is for a certain object property
functional validity
whether a cue is actually used
e.g colour blind people do not use colour as a cue
external world
internal world
lens model
Visual perception frameworks
empiricism
Perception is made of constructive processes that register the stimulus and add something using pre-existing knowledge, muchly from "top-down processes" (based on internal knowledge of the world
- hanmanan von Helmholtz 1821-1894
- psychological optics 1909-11
- richard gregory
- perception as hypothesis testing
- devised and popularised many new perceptual demonstrations
The information hitting our retinas us ambiguous
so perception must be a constuctice processs to use those images to extract real world properties
Form perception
VonHelmholtz
the visual world is not random and some objects are more liely to produce retinal images than others
our brian perform unconcious inferenecses using knowledge about statistical regularities in the world (e.g we know that t closing door produces a rectangle image so we correct for it)
Gregory
modern idea of VonHelmholz
sensory inputs trigger events in our nervous system (bottom up processes)
rgwn existing knowledge in our brain inerects with these inputs and create psychological data
based on this data, hypothesizes are made and tested by our brains to interpret the ambiguous physical world (top-down processes)
Example
- a vertical (or near vertical) line is perceived to be about 10% longer than a horizontal line of the same length on the retina
- perception of form does not correspond to what is in the retina
T illusion
- Objects tend to produce shorter near-vertical than horizontal retinal images because of foreshortening
- This regularity leads us to overestimate the length of near-vertical lines
- idea of unconscious intereferences
Forn constancy
our visual system compensates fro the foreshadowing of elongated objects extending in depth so objects don't seem to change shape and size as they change orientation or distance
perspective cues
using an illusion of tiles, you can see that they get smaller as they get further away, this makes the illusion that they are different sizes
form constancy demonstrates how we use internal knowledge (top-down processes) to interpret ambiguous information
visual mental imagery
we can recognize impoverished pictures (pictures with bits missing) becasue our knowledge that drive top-down processes that test hypothesises about the objects can fill in the gaps
short term memory representations give rise to the experience of "seeing with the mind's eye" which is based on stored long term memories
there are multiple types and they aren't limited to visual memories of events that we've experienced
- practical components
- forensics (false memories)
- psychotherapy
- mental practice
- brain-computer interfaces
- Many of the experimental setups used to justify the idea of unconscious inferences or of perception as hypothesis testing are very impoverished
- Do these ideas still work in richer and less ambiguous environments?