Lecture 2: Making Sense of Visual Input Flashcards
Which paradigm is this?
- Preferential looking paradigm.
- You would expect the baby to look longer at the dog (more saturated with colour and details).
*add habituation paradigm slide!!
kid will look longer at black cat because it is novel stimulus
Visual development review
- 2 paradigms: preferential looking and habituation paradigms.
- At birth: infants see in grayscale
- Other senses are more developed than vision.
- 5 months: colour perceptions is adult like.
- 2 months: infants can see the colour red
- 4 months: capable of object segregation using cue of movement.
- Sensitive period for binocular depth perception (0-3 years)
- 6 months: able to use monocular dept cues, assessed using cliff
- 8 months: visual acuity + visual scanning is adult-like
- Infants like to look at faces due to innate preference for top-heavy stimuli
- Almost right from birth infants prefer to look at their mom’s face.
- 9 months: face specialists as demonstrated by the other-race effect due to perceptual narrowing (synaptic pruning).
Familiarity vs Novelty
- Infants prefer to look at stimuli that are:
- More complex, more saturated in colour
- Familiar
- Natural familiarity: Stimuli infants experience often in their lives
-
Lab-induced: Familiarize infant to a new stimulus by first exposing them to it for a brief amount of time
- We then expect the infant to show a preference for the familiar stimulus when paired with a new stimulus.
Lab-Induced Familiarity
- in a lab, familiarize a baby with a photo of the dog
- show them the dog next to another stimulus
- expect baby to be more interested to look at dog shown because they are familiar with it.
What does exposure time to an initial stimulus determines what?
*In lab settings, length of exposure time to an initial stimulus determines whether an infant will show a familiarity or novelty preference:
* Short exposure = familiarity preference
* Long/ repeated exposure = novelty preference
Sweet spot of showing a stimulus just enough so that they are familiar with it but not too much that they become bored with it.
Making sense of visual input
*Humans create meaning out of their perceptions in 2 ways
* Intermodal perception
* Categorization
Intermodal Perception
*The coordinated perception of a singular object or event through 2 or more sensory systems. Most of the time when we are experiencing something, we are experiencing it in more than one modality (visual, auditory, smell…)
* Often vision and at least one other sensory modality - we rely a lot on visual input
*Intermodal perception is present very early on
Combining Vision and Touch
*Study: Can newborns integrate vision and touch?
* Familiarization: Infants sucked on a pacifier that they couldn’t see (familiarized it with pacifier) - could feel the shape and spikes on it.
* Preferential-looking procedure: Picture of the pacifier they had sucked on vs. picture of a pacifier of a different shape and texture
*Results: Newborns looked longer at the pacifier that they had sucked on
* i.e., looked at familiar pacifier (they used their tactile information to pick the pacifier they had sucked on).
*Shows that ability to combine visual information with touch is present from birth
Combining Vision and Auditory Info
*Study: Can infants combine vision with sound?
* Preferential looking procedure: 4-month olds simultaneously watched two videos side-by-side
* Video of someone playing peekaboo vs. video of someone playing drums
* At the same time, heard audio of person saying “peekaboo” –> cant hear the sound of the drums.
* i.e., audio is synchronized with only one video
Combining Vision and Auditory Info (results)
Results: looked longer at the person playing peekaboo vs. person playing drums
* Shows that infants can integrate visual and auditory information
* Learn to associate that open mouth = speech sounds
* Important for language development because children need to understand that speech sounds are linked with a moving mouth. Need this ability to learn language
Categorization in Infancy
- infants make sense of the world by making categories.
- they can categorize things by the age of 3 months old.
Study: - Habituated babies to cats, become less and less interested at each presentation of a cat.
Categorization in Infancy (results)
- Categorization begins in infancy
Study: - Showed 3 month olds various pictures of cats
- Habituated to the general category of cat
- Looked at novel cat photos less and less
- Test: photo of a dog
*Results: Infants looked longer at the dog
*Suggests that infants saw all the cats as a single category and the dog as a different category
- they never saw the same cat over and over again, they saw different cats
- realize that the dog is something different from the cats (created a category)
Categorization in Infancy
*Infants also form more general categories than “cat”
*Study:
* Habituation: 6 month olds habituated to photos of mammals
* Then, on test trial, looked longer at non-mammals (i.e., bird or fish)
* Shows that infants had formed category of mammal by recognizing similarities between mammal
Perceptual Categorization
How are they making these categories???
* Infants group things together that are similar in appearance, focus on similarities in shape.
- ie: in previous mammal question - they pick up on the fact that mamamals have 4 legs.
* Study: 12 months old
* Experimenter picked up target object and demonstrated that it rattles
* Infants were more likely to assume that an object of a similar shape also rattles vs. objects similar in colour or texture.
- more focused on the shape (opposed to the colour and texture). This is how we know infants are prioritizing the shape.
Pitfalls of Perceptual Categorization
Focus on similarities in shape results in:
- Difficulties understanding exceptions
* E.g. Failure to categorize a snail as an animal because doesn’t have legs - Mistakenly categorizing objects together
* E.g. Categorizing birds and planes together based on both having wing
* hard to understand that boats is a vehicle (because it doesnt have wheels)
Conceptual Categorization
- Around 9-month-olds, children begin categorizing objects based on their shared function or behaviour
- But still mostly categorize based on perceptual similarities
- 9-month-olds divide objects into 3 broad categories
Object Categorization Beyond Infancy
- By 2-3 years of age, children start to form category hierarchies
- Category hierarchies: organize object categories by set-subset relations.
- Allow for finer distinctions among objects within each level.
- allows child to draw valuable inferences.
Category Hierarchies
*Children usually learn basic level first
* because objects at the basic level have obvious similarities
* Similarities at superordinate level are less obvious and differences between subordinate levels are hard to detect
