Perception and Brain Development

Question 1

What is visual acuity? How does visual acuity develop?

Answer 1

In adults, cones are most densely packed around the fovea
By contrast, cone cells are evenly distributed across the infant retina
This means that peripheral vision is similar to adults, but foveal acuity is immature

Question 2

How do developmental scientists test infant visual acuity using grey and striped (black and white) panels?

Answer 2

Researchers present infants with two screens, one containing a solid grey panel and the other a panel of black and white stripes. When the black and white stripes move progressively closer together, the stripes blend visually until the striped panel resembles the grey panel (black and white blend to make grey.) A researcher (who doesn’t know which side contains the striped pattern) decides on each trial whether the striped panel was on the left or the right based on infant looking and other behaviours.

Question 3

What are monocular cues and binocular cues? What is the difference between the 2?

Answer 3

Depth and distance are signalled by cues from both eyes, known as binocular cues, and also from one eye, known as monocular cues. Binocular cues arise because the two eyes have different views of the world, so they send different signals to the brain. Monocular cues also provide information about depth and distance through information about visual angles: Distant objects produce smaller angles and smaller objects on the retina compared to close objects.

Question 4

What is temporal synchrony in regards to perception?

Answer 4

When different types of perceptual information occurs at the same time, creating a unitary perceptual experience.

Question 5

Infants are able to categorise what they’re looking at. What categories do they use, conceptual or perceptual?

Answer 5

Infant categories, differ from adult categories in that infants often group things together based on their physical appearance (perceptual categories) rather than their use, what they do, or how you use them (conceptual categories)

Question 6

What is perceptual narrowing?

Answer 6

A diminished ability to distinguish among stimuli because of a lack of experience with them.

Question 7

According to Tamis-LeMonda, infants are in a constant state of exploration. What are the 4 things that they do?

Answer 7

Try new things
Gather evidence
Seek to learn about their environment
Each time they fail they try again

Question 8

How is infancy defined? How old? Who do they need support from? What support do they need?

Answer 8

Birth to 2 years of age
A period of relative helplessness
Depend on caregivers for survival
Need to acquire a vast repertoire of skills and knowledge to reach reproductive age
Collaboration between caregiver and infant

Question 9

What is the process of sensation, perception, understanding and action?

Answer 9

stimulus -> sensory receptors -> neural impulses -> perception

Question 10

How many rods and cones are there? Where are rods located? What are rods and cones useful for in terms of vision? Which one has high or low visual acuity?

Answer 10

Rods:
120 million per eye
Respond to lower visual light intensities
Low visual acuity
Located on the outer region of the retina
Great for night vision

Cones:
6 million per eye
Respond to greater light intensities
Necessary for colour vision
High visual acuity

Question 11

When is infant eye anatomy present? Is infant eyesight clear? At infancy, are coordinated eye movements possible?

Answer 11

Anatomically present at birth but not mature
Coordinated eye movement isn’t possible
Near-sighted and blurry sight
Cornea, lens and retina are immature

Question 12

What is the gestalt theory of perception?

Answer 12

Nature based theorists
Believed infants have innate perceptual abilities enabling perception of ‘wholes’
Organised perception
From early in life

Question 13

What is the ecological theory of perception? What are the 3 most important arguments? What did Piaget suggest?

Answer 13

Nurture emphasising theorists
Piaget noted that perceptual skills emerge before concepts like size and shape constancy which emerge steadily
This theory highlights that: the environment is dynamic, perceptual systems have evolved and learning involves judging possibilities for action

Question 14

Gibson and Gibson. How specific is our perceptual systems? How does learning occur? From this, how do people’s behaviour change?

Answer 14

Argued that perceptual systems have evolved at a species specific level
Learning occurs through trial and error such as failed attempts to reach an object
People perceive, act and adjust to fine tune behaviours

Question 15

Fantz study. What is the visual preference task method? What is perceptual discrimination?

Answer 15

Infants will look longer at one stimulus when paired with a second stimulus.
Recognised that by showing a consistent preference for one over the other, infants where showing evidence of perceptual discrimination

Question 16

What is shape constancy and size constancy?

Answer 16

The perception of an object as having a constant size despite changes in the size of the retinal image is called size constancy. Similarly, the perception of an object as having a constant shape despite changes to the retinal image is referred to as shape constancy.

Question 17

In a study against faces, complex patterns and plain stimuli, what pattern do infants look at the longest?

Answer 17

Neonates (28 days old) percentage of total fixation time
Preferential looking method
Faces: 41%
Complex patterns: 20%
Plain stimuli: 9%

Question 18

Fantz. What is the Habituation- Recovery task used for? When scientists use this test, what stimuli are they looking at infants responses for?

Answer 18

Created the habituation-recovery technique, now commonly known as visual paired comparison task
Preference tasks rely on a spontaneous preference, habituation can be used to create or induce preferences
This technique looks at responses to novel stimulus

Question 19

Fantz. In the Habituation-Recovery study. What was the method? What age do they show habituation? What were the age groups? What is a fixed trial?

Answer 19

Infants aged 2 months old and above generally habituate to a stimulus (photographs and adverts from magazines) and show a preference for the novel
Older they are, the more habituation they show
No preference was shown in the youngest group

Groups: 1-2 months, 2-3 months, 3-4 months and 4-6 months

Fixed trial: predetermined exposure

Question 20

What is an infant-controlled study? What is the habituation criteria?

Answer 20

Infant controlled= habituation determined by the individual infant’s looking time

Habituation Criteria: when the duration of looking on any 3 successive trials totals 50% or less than the total of the first 3 trials

e.g. trial 1 = 45 seconds, trial 2 = 30 seconds, trial 3 = 25 seconds, trial 4 = 20 seconds, trial 5 = 18 seconds, trial 6 = 15 seconds, trial 7 = 10 seconds

trial 1, 2 and 3 = 100
100 divided by 2 = 50
trial 4, 5 and 6 = 53
trail 5, 6 and 7 = 43

Question 21

Where is visual acuity highest? What is the relationship between saccades and the fovea?

Answer 21

Visual acuity is highest in the fovea
Saccades point the fovea to the areas of interest - bring them into focus

Question 22

What are saccades? At what age do saccades develop?

Answer 22

Newborns cannot make reliable saccadic movements

Make errors and sometimes produce saccades in steps

Saccades are mature by at least 4 months of age

Saccades: rapid eye movements between two fixed points

Question 23

At what age can newborns scan the environment for objects? At how old is focus good and at how old is focus adult-like?

Answer 23

From birth, newborns can scan the environment for objects of interest and tracking moving objects
Movements are slow and inaccurate but focus is good by 2 months and nearly adult like by 4-6 months

Question 23

What is exogenous and endogenous scanning in newborns?

Answer 23

Endogenous: newborns will display short eye movements, even in dark rooms
Exogenous: Newborns respond to stimulation from the environment

Question 24

How far can an infant see? Why can they only see so far in an evolutionary perspective?

Answer 24

Focus at 30cm away regardless of the object's distance Promotes attention to the important things, e.g. mothers face and breast feeding, and limits distraction to other objects

Question 25

What is contrast sensitivity? Are infants drawn to high or low contrast?

Answer 25

Contrast sensitivity: the minimum difference in brightness between an image and its background that infants can perceive, contrast sensitivity improves as the eyes biologically mature Infants are drawn to high areas of contrast

Question 26

What is the method of the visual cliff test?

Answer 26

They placed infants in a crawling position on a starting platform, at the edge of which was an apparent drop-off of 90 cm. In reality, this cliff was covered with a strong sheet of clear plastic. In the ‘shallow’ condition, the floor was placed right under the glass, signalling that it was safe to cross. Infants crawled across the cliff in the shallow condition, but did not crawl when the drop-off seemed deep, suggesting that depth cues informed their behaviours. However, this is not the only factor: it is worth being aware that infants also rely on social cues to determine whether it is safe to cross a cliff.

Question 27

How old are babies when binocular cues emerge? At what age do they improve?

Answer 27

Sensitivity to binocular cues emerge between 2-3 months of age and improve rapidly in the first year of life

Question 28

What are kinetic depth cues? What are motion parallel cues? At what age do motion parallel cues occur?

Answer 28

Kinetic depth cues: movement of body or objects, e.g. 3-4 weeks babies will blink rapidly at objects heading towards them Motion Parallax: close objects move more than distal objects when you are moving. Occurs in objects at 16 weeks of age

Question 29

How does texture and occlusion help us understand more about distance? At what age do these occur?

Answer 29

Textures closer to us will contain more detail and occlusion (when one object completely or partially blocks another object from view) of objects helps us to understand about distance. Develop between 5-7 months

Question 30

Pascalis, de Haan, & Nelson, 2002) At what age can babies distinguish between different types of monkeys faces? What brain theory does this reflect? At what age does this ability decline?

Answer 30

Early in life, babies can distinguish between different primate faces This reflects plasticity in facial processing, but this ability declines between 6 and 9 months of age

Question 30

What is retinal disparity? What is stereopsis?

Answer 30

Eyes are separated in space and give different views of the world – retinal disparity Stereopsis: the perception of depth from binocular disparity: different incoming images from each eye.

Question 31

Kelly 2005. Do babies prefer to look at their own-race faces or other-race faces? At what age does this occur?

Answer 31

Tested preference for faces of different races in neonates and 3 month old infants Newborn infants don't look preferentially at own-race faces or other-race faces 3 month old infants look preferentially at own-race races when paired with other-race faces

Question 32

Kelly 2005. Between Israeli and Ethiopia infants, do they have a preference for own-race or other-race faces? What is a social impact of how Ethiopia infants don't develop a preference between 2 races? What are these 2 races?

Answer 32

Own-race preference also reported in Israeli and Ethiopian infants Ethiopian infants raised in an absorption centre (were in Israel awaiting houses) exposed to Caucasian and African faces showed no preference

Question 33

A phoneme discrimination study. What was the method of this study? Do infants attend longer to nonspeech or speech sounds? And at what age?

Answer 33

Nonspeech sounds vs novel speech sounds When infants looked at the monitor, the sounds played, and when they looked away the sounds stopped. When infants looked back to the monitor, researchers presented a different sound. Although researchers made sure the nonspeech sounds were comparable to the speech sounds on critical features, such as pitch, infants as young as two months attended longer to the speech sounds than to the nonspeech sounds.

Question 34

Kelly 2007-2009. What were the 4 different racial faces in this study? What was the method? At what age did infants show recognition between each race-face category?

Answer 34

Tested own race face recognition in 3-6 months old and 9 months old Caucasian, Chinese, Middle eastern and African faces Initially see one face on the screen until they habituate, in the test face they have both the novel and unfamiliar face. They then have the same novel face at a different angle 3 months old: recognition in all categories 9 months old: only show recognition in their own-race face