Lecture 5: Perceptual development

Question 1

Sensation

Answer 1

the processing of basic information from the external world by sensory receptors in the sense organs and the brain. Sensory input is often ambiguous or incomplete.

Question 2

Perception

Answer 2

organising and interpreting sensory information about the objects, events, and spatial layout of our surrounding world. Perception organises sensory input into representations that the brain can use.

Question 3

Perception research in infants

Answer 3

Measured how long infants look at stimuli.
Fantz used this to demo that infants had visual preferences.

Question 4

what did newborn perception research reveal

Answer 4

infants could discriminate between stimuli using the preferential looking and habituation techniques

Question 5

Preferential-looking

Answer 5

involves showing infants two patterns or objects at a time to see if the infants have a preferences for one over the other.

Question 6

habituation

Answer 6

involves repeatedly presenting an infant with a given stimulus until the response declines. If the infants response increases when a novel stimulus is presented, the researcher infers that the baby can discriminate between the old and new stimuli

Question 7

Operant conditioning

Answer 7

for example, rewarding the infant with a particular sound (or taste, or smell) according to their sucking pattern. Measure which pattern the child responds with to ascertain which reward is preferred. can be used in prenatal listening.

Question 8

William James

Answer 8

“The baby, assailèd by eyes, ears, nose, skin, and entrails at once, feels it all as one great blooming, buzzing confusion”
However is is not as chaotic as james predicted.

Question 9

what can newborn children see

Answer 9

Visual acuity- sharpness of visual discrimination

Question 10

How does visual acuity develop

Answer 10

The sharpness of infants’ visual discrimination develops so rapidly that it approaches that of adults by age 8 months and reaches full adult acuity by 6 years of age

Question 11

How can visual acuity be estimated

Answer 11

An infant’s visual acuity can be estimated by comparing how long the baby looks at a striped pattern such as this one versus a plain grey square of the same size and overall brightness

Question 12

Contrast sensitivity

Answer 12

Very young infants (up to 2 months) prefer to look at patterns of high visual contrast because they have poor contrast sensitivity (the ability to detect differences in light and dark areas)
This is because the cones (light-receptors) of the eye, which are concentrated in the fovea (the central region of the retina), differ from adults’ in size, shape, and spacing

Question 13

Childrens eyes

Answer 13

Immaturity of children’s cone cells - not very well developed
Light sensitive neurons concentrated in the fovea in the retina
Different size and shape and further apart than in adults
Newborns have about 20/120 vision
develops rapidly from then
Implications for colour vision

Question 14

Colour vision

Answer 14

Very young infants have limited colour vision, although by 2-3 months of age their colour vision is similar to that of adults’ (Kellman & Arterberry, 2006)
Infants can discriminate between two bright, vivid colours (high contrast) better than between two faint, pastel colours (low contrast)- due to cone cells

Question 15

Scanning

Answer 15

Scanning One-month-olds (a) scan the perimeters of shapes, while two-month-olds (b) scan both the perimeters and the interiors of shapes (Maurer & Salapatek, 1976)- eyes move around something stationary. Begins at perimeter then develops to interior

Question 16

Tracking

Answer 16

Tracking Although infants begin scanning the environment right away, they cannot track even slowly moving objects smoothly until 2 to 3 months of age (Aslin, 1981)
Smooth tracking movements

Question 17

Faces

Answer 17

From birth, infants are drawn to faces because of a general bias toward configurations with more elements in the upper half than in the lower half

Newborns look longer at the left-hand images than the right-hand images (Simion et al., 2002)
From paying attention to real faces, the infant comes to recognize and prefer his or her own mother’s face after about only 12 cumulative hours of exposure (Bushnell, 1998)-

Question 18

Developing face expertise- Pascalis et al (2002)

Answer 18

Adult humans able to tell the two (unfamiliar) men apart quite easily , but may still not be sure whether the two monkey photos are of different individuals or not
Pascalis et al. (2002) – adults and 9-month-old children have difficulty distinguishing monkey faces
But 6-month-olds just as good at distinguishing monkey faces as human faces-
Expertise helps us tell human faces apart.

Question 19

Developing face expertise (Quinn et al., 2002)

Answer 19

From birth onward, infants look longer at faces that adults find more attractive than those adults rate as less attractive
Prefer female faces by around 3 months of age, unless primary caregiver is male (Quinn et al., 2002)
With experience, infants not only develop a preference for the type of face they see most often, but also come to understand the significance of different facial expressions – ~4-5 months

Question 20

Pattern perception

Answer 20

Two-month-old infants can analyse and integrate separate elements of a visual display into a coherent pattern
Subjective contour.
Illusory square.

Question 21

Kaniza arrangement

Answer 21

Only infants familiarised to the Kaniza arrangement in the top left show a significant preference away from squares (Ghim, 1990).
Hence, they must perceive a subjective square.
May not be present in newborns. Acuity?

Question 22

Perceptual constancy

Answer 22

The perception of objects as being of constant size, shape, colour, etc., in spite of physical differences in the retinal image of the object
If an infant looks at the larger, but further away cube, researchers will conclude the child has size constancy (Slater et al., 1990) - they understand that it is twice as big but twice as far away.
Supporting the nativist position, visual experience does not seem to be necessary for perceptual constancy

Question 23

Object segregration and movement

Answer 23

Infants who see the display in figure (a) perceive it as two separate objects, a rod moving behind a block
After habituating to the display, they look longer at two rod segments than at a single rod (b), indicating that they find the single rod familiar but the two segments novel
If they first see a display with no movement, they look equally long at the two test displays
This result reveals the importance of movement for object segregation (Kellman & Spelke, 1983)

Question 24

Object segregation and gravity

Answer 24

young infants use common movement to perceive object segregation
Older infants, like adults, can use additional sources of information for object segregation, including their general knowledge about the world

Question 25

Depth Perception

Answer 25

young infants use common movement to perceive object segregation
Older infants, like adults, can use additional sources of information for object segregation, including their general knowledge about the world

Question 26

Stereopsis

Answer 26

Process by which the visual cortex combines the differing neural signals caused by binocular disparity (the slightly different signals sent to the brain by the two eyes)
Emerges suddenly at around 4 months of age (Held et al., 1980)

Question 27

Depth perception

Answer 27

about 6–7 months of age, infants become sensitive to a variety of monocular or pictorial cues, the perceptual cues of depth that can be achieved by one eye alone
These include relative size (larger is closer), interposition (overlapping) and linear perspective (convergence of parallel lines)- meaning a single point of origin

Question 28

7 month old infant and depth perception

Answer 28

This 7-month-old infant is using the monocular depth cue of relative size (Yonas et al., 1978)
Wearing an eye patch to take away binocular depth information, he is reaching to the longer side of a trapezoidal window - aims window.
This behaviour indicates that the baby sees it as the nearer, and hence more readily reachable, side of a regular window

Question 29

Pictorial representations

Answer 29

Despite the fact that even newborns can recognize two dimensional versions of three dimensional objects, children must come to understand their symbolic nature
Before they reach about 19 months of age and have substantial experience with pictures, infants and toddlers attempt to treat pictures as though they were real objects (DeLoache et al, 1998)

Question 30

How does hearing develop

Answer 30

Although the human auditory system is relatively well developed at birth, hearing does not approach adult levels until age 5 or 6

Question 31

Auditory perception

Answer 31

Newborns turn toward sounds, a phenomenon referred to as auditory localization.
Wertheimer (1961) – 10 mins old
Clarkson & Clifton (1991) – Continuous sound is best.

Infants are remarkably proficient in perceiving subtle differences in human speech

Question 32

Perception of speech sounds

Answer 32

At 2 months of age (Eimas, 1985):

Allow infant to suck on soother (dummy) that is connected to a computer and measure baseline sucking rate

Present phoneme (/pa/) repeatedly

Sucking rate first increases and then infant habituates (i.e., returns to baseline sucking rate)

Present new phoneme (/ba/)

Infant dishabituates (i.e., sucking rate increases)

Question 33

Perception of music (biological)

Answer 33

Biological foundation

Butt and Kisilevsky (2000)
Heel lance procedure on premature infants 31 weeks GA

Heart rate returned to normal more quickly when played Brahms lullaby (regardless of instrument)

Not present for infants <31 weeks GA (gestational age)

Control condition?

Question 34

Perception of music

Answer 34

Infants share the strong preferences adults have for some “pleasing” music sounds over others (Trainor & Heinmiller, 1998)

Infants respond to rhythm and temporal organisation in music, preferring music that had pauses between musical phrases rather than in the middle (Krumhansl & Jusczyk, 1990)

Infants are also sensitive to melody, showing habituation to the same tune (a particular sequence of notes) regardless of changes to the musical key (pitch) (Chang & Trehub, 1977)

Question 35

Preference for sweetness shown at birth studies. Marlier

Answer 35

Marlier et al. (1998)
Newborn infants prefer the smell of their “own ‘’ amniotic fluid relative to that of another baby.

Question 36

Teicher & Blass (1977)
taste and smell

Answer 36

Amniotic fluid promotes post-birth feeding behaviour in RATS
Baby rats navigate to mother rat for feeding very soon after birth
If mother rat is washed immediately after birth – pups don’t find food source

Question 37

Marlier and Schall

Answer 37

Newborns prefer the smell of breast milk, their natural food source (Marlier & Schall, 2005)
Regardless of whether they have been breastfed or bottle fed (i.e., have never tasted breast milk)

Question 38

Taste and smell in the newborn

Answer 38

By two weeks of age, babies appear to be able to differentiate the scent of their own mothers from that of other women, an ability shared by a variety of infant mammals (MacFarlane, 1975)

Question 39

Touch and intermodal perception (video)

Answer 39

Very young infants link sight and sound, oral and visual experience, and visual and tactile experience how info from more than once sense is put together

When two videos are presented simultaneously, 4- month-old infants prefer to watch the images that correspond to the sounds they are hearing (Spelke, 1976, 1979) - will watch video that corresponds with sounds

Using a similar technique, researchers have found that by 5 months of age, infants associate facial expressions with emotion in voices (Walker-Andrews, 1997)

Question 40

Intermodel perception (rings)

Answer 40

Infants held two rings, one in each hand, under a cloth that prevented them from seeing the rings or their own bodies

For some infants the rings were connected by a rigid bar and therefore moved together

For others the rings were connected by a flexible cord and therefore moved independently

All the infants were allowed to hold and feel just one or the other type of rings until they had largely lost interest (habituated).

They were then shown both types of rings and looked longer at the rings that were different from those they had been exploring with their hands (Streri & Spelke, 1988)