Vision: Development of Scene Perception Flashcards
How do we study visual development?
Looking behavior = e.g Preferential looking
Neuro measures = EEG, VEP, fNIRS
Observation / deprivation = Behaviour, Naturally occurring – cataracts, ‘Selective rearing’ (not humans)
Things that aren’t children= Neural networks, Robots / AI, Adult
Example of studying at baby’s looking bhvr
Preferential looking = Fantz 1956, Fantz & Nevis, 1967 saw the applications
Other ways to use looking behaviour for babies
Habituation
Novelty preference
Eyetracking
VoE
reliable + reveal biases in the infant visual system e.g bias to high contrastimages and ‘face like’ stimuli
Adult vision
Visual Acuity
Colour
Depth
Size
Shape
Orientation
Segmentation
Transparency
Opaqueness
Motion
Constancy
Etc..
What is visual acuity?
Poor at birth, but by 36 months old children have 20/20 vision
Although acuity is poor, the general pattern for CSF is very similar to adults
Kiorpes (2016) = development of contrast sensitivity
The world is very blurry when kids are very young
Is there an advantage to low initial acuity?
immaturity of the infant visual system = provide the best learning ground for discriminating faces.
Teaches weighting of configuration of faces over local processing
What is the Neural Net (vogelsgang et al, 2018)?
The image gets clearer after seeing multiple faces. Integrate where the everything.
Evidence for impaired face perception - cataracts
People w/ cataracts
Have the same amount of cell maturation but a different amount of experience you get when you are trying to see
People can see the are different people straight away = takes longer for people w/ cataracts. Real world evidence/
LeGrand et al 2001,
Geldart et al 2002.
What does low initial acuity suggest?
critical periods = period in development when perceptual
systems are sensitive to environmental stimuli
Explain colour vision in babies
although all the cones are present = infant retina + pathways to colour = immature at birth.
But, infants can see some colour from birth + by 3-4 months old = trichromatic.
Adams (1989)
newborns = look longer at the red-like than the achromatic light (grey). Look at blue + achromatic light equally. They have a reddish colour vision but not yet blue dimension
How does colour discrimination in colour vision develop in babies?
Colour discrimination is half with every doubling of age + ratio of input of the cones is the same across the
lifespan
8m = is 2x of 4 months
How does depth and size perception develop in babies?
Very young children can perceive depth, as illustrated by heart rate measurements
Visual clef experiment = support this
Size constancy = some form in newborn infants, but the integration between perception + action = unperfected.
Young children some skills for size constancy, but don’t necessarily integrate across visual cues (failing to integrate cue for depth perception, Nardini et al. 2010)
Name studies supporting size constancy in newborns
Slater et al (1990)
Granrud, et al (1987)
What is perceptual learning?
Learning to make sense of the perceptual input that we receive
What is a scale error?
A failure to integrate visual info and with the information they have already learnt
how does early visual experiences affect the way a person may behave as an adult?
Although biases in infant looking behavior from birth = refinement of perception based on visual experience in the first year of life
very important = significant influence on perception
What is perceptual narrowing?
Experience/ lack of experience shapes perceptual experience = ‘use it or lose it’ refinement
A critical period for stimulation.
What happened in Pascalis, de Haan & Nelson , 2002
6 vs 9 month old
see also similar effects for baby faces
Babies 6m = can identify the differences better than 9mths
Lost that ability at 9m
What is the other ethnicity effect
better at discrimination your race than other races
What are the effects of natural scenes?
Holes = trypophobia
Trypopobic images = excess of energy at the mid spatial frequencies = matches the spectral profile of some
hazardous animals, such as snakes.
Aesthetics are influenced by low level properties of an image.
what is natural scene statistics?
How environment vary in predictable and measurable ways e.g golden ratio
We expect that our perception is shaped by fixed adaptations and
plastic adaptations.
Any scene that you can come across
What is image analysis?
Images = broken down into low level + high level properties. We can find what’s common across all natural scenes + how / if the visual system lines up with it.
Colour information = e.g. Colour intensity (saturation). Range of colour
Spatial information = e.g Fractal dimension. Spatial frequency (low detail and fine detail
What is the applications of image analysis?
Companies like Netflix = use more/ less saturation on thumbnails to get people to watch them
What is spatial stats in the natural science
Natural scenes have a 1/f distribution of spatial frequencies, and neurons in the primary visual cortex have response profiles
optimised to process this information.
What contrast information is present?
Low spatial frequency (fine detail) + high spatial frequency (low detail) in this image
Way to describe the spatial freq. contrast vary in an image
Which slope are adults sensitive to?
The are sensitive to scenes that vary around 1/f slope and insensitive to scenes that aren’t
Children not sensitive until 10 bc immaturities in low level vision
Describe natural stats and colour
The spectral sensitivities of human colour receptors have evolved to optimally represent the variation in colour of blood flow
and diets of our ancestors
Natural scenes contain the greatest amount of variance along one particular direction in colour space (cerulean line : blue
yellow’. This is also the way that sunlight and skylight vary.
Natural scene statistics in infancy can impact on adult colour perception into adulthood
How is aesthetics and natural scenes linked ?
More ‘natural’ distributions of colour are higher in artistic merit, and less natural distributions are more uncomfortable to look
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