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?