HUMAN DEVELOPMENT 1
PSYCHOLOGY 3050:
Infant Perception and Cognition Ch 4
Dr. Jamie Drover
SN-3094, 864-8383
e-mail – jrdrover@mun.ca
Winter Semester, 2015
Basic Perceptual Abilities of Young Infants
• It was once thought that infants were born deaf and
blind and with limited pain sensitivity.
• Although far from mature, all of the infant’s senses
are functioning.
– They even prefer some sights, smell, and sounds over
others.
• Infants are also sensitive to pain
– ELBW infants’ response to pain is affected by repeated
painful episodes.
Basic Perceptual Abilities of Young Infants
• Vision and hearing develop rapidly over the
first year.
• Tactile stimulation is very important to
infants.
– Pre-term infants who receive massage gain more
weight, spend more time awake, and display more
advanced cognitive and motor skills than do
normal treated preterm babies (Schanber & Field,
1987).
Basic Perceptual Abilities of Young Infants
• The chemical senses (taste and smell) develop early.
• Six-day olds prefer the scent of their mother’s breast
pads over those of a stranger (Macfarlane, 1975).
Methodologies of Infant Perception
• To assess infant perception, we must observe a
behavior that an infant can control and use that to
infer perception.
Sucking Response
• Researchers often use infants’ sucking rates.
• DeCasper and Spence (1986) had pregnant women
read one of three passages aloud twice per day.
Methodologies of Infant Perception
• Shortly after birth, headphones were placed on the
infants.
• One of several passages could be played over the
headphones based on sucking rates.
• Infants would alter their sucking rates in order to
hear the reading of familiar passages.
Methodologies of Infant Perception
Visual Preference Paradigm
• Fantz (1958, 1961) placed
babies in a looking chamber
and presented them several
visual stimuli.
• If they spend more time
gazing at one pattern more
than another, it is assumed
they can discriminate
between them.
Habituation/Dishabituation
• Habituation: the decrease in response to a stimulus
as a result of repeated presentations of that
stimulus.
• Infants can habituate to a visual stimulus.
• The longer infants are exposed to a stimulus, the less
time they will spend looking at it.
• Habituation occurs when there is a substantial
decrease in looking time following repeated
presentation.
Habituation/Dishabituation
• Often defined as when fixation to the stimulus is
50% of what it was initially.
• If a new stimulus is then presented, the infant may
show a sudden increase in looking time.
– This is dishabituation.
• Thus, the infant can discriminate between the two
stimuli.
• Also indicates that infants can remember the earlier
stimulus.
Habituation/Dishabituation
Habituation/Dishabituation
Habituation/Dishabituation
• Using this paradigm, Friedman (1972) found
evidence that 1- to 3-day-old infants will habituate
and dishabituate to visual stimuli.
• Newborns are capable of visual memory.
The Development of Visual Perception
• Infants can perceive light (pupillary reflex) but
because of poor accommodation, much of what they
see is blurry.
– Accommodation is adult-like at 3 months.
• Newborns can track a moving object, but the eyes do
not always move in harmony.
• Convergence and coordination are adult-like by 6
months.
Testing Infants’ Visual Acuity
• Visual acuity of newborns is
20/600 to 20/400.
• Can be tested using forcedchoice preferential looking.
• Infants are presented with
rectangular cards that contain
black and white stripes on
one side of a central
peephole, while the other
side is blank.
– Teller Acuity Cards
Testing Infants’ Visual Acuity
• Given an infant’s
preference for patterned
stimuli over unpatterned
stimuli, if he/she can
detect the stimulus,
he/she will fixate it.
• A naïve observer must
determine the location of
the stripes based on the
fixation of the child.
Testing Infants’ Visual Acuity
• The thinnest stripewidth at which the observer can
determine the location of the stripes provides a
measure of visual acuity.
The Development of Visual Perception
• Vision is poor at birth because the
fovea is underdeveloped.
– Point on the retina where vision
is sharpest. Packed with cones.
• The infant fovea contains large, less
densely packed cones.
• Newborns can discriminate
between red and white, but can not
differentiate blue, green, and
yellow from white (Adams et
al.1994).
The Development of Visual Preferences
• Until 2 months of age, an infant’s visual preferences
are affected by physical properties of the stimulus.
• Babies prefer moving stimuli over stationary stimuli.
– See Haith (1966) p. 193.
• Infants prefer high contrast stimuli over low contrast
stimuli.
– See Salapatek and Kessen (1966) p. 193.
The Development of Visual Preferences
The Development of Visual Preferences
• Infants at 1 month of
age focus their
attention primarily on
the outside of a figure.
• Externality effect.
The Development of Visual Preferences
• At 4 months, infants start to show a preference for
vertical symmetry.
• They prefer to process stimuli that are vertical and
symmetrical as opposed to asymmetrical and
horizontal stimuli.
• Curvature, or curvilinearity is a also important to
infants.
– Fantz demonstrated that infants sometimes prefer cuved
stimuli over linear stimuli.
The Development of Visual Preferences
• Infants as young as 3 to 4 months of age prefer the
curvilinear and concentric stimuli (Ruff & Birch, 1974).
• Even newborns prefer curvature.
Psychological Stimulus Characteristics
• At around 2 to 4 months, psychological
characteristics of a stimulus become important to
infants.
– Eg., familiarity and novelty
• Kagan (1971) proposed that at 2 months, infants
form schemas.
– Sensory representations of a stimulus.
– The similarity of a stimulus to a previously determined
stimulus will determine attention.
Psychological Stimulus Characteristics
• Infants are most attentive to
stimuli that are moderately
discrepant from a schema.
– Discrepancy principle.
– They are less attentive to stimuli
that are highly familiar, or highly
discrepant.
• McCall et al. (1977) familiarized 24 month-old infants to stimuli and
later showed them stimuli that
varied in their similarity with the
original.
Psychological Stimulus Characteristics
• Stimuli that were highly similar, or highly discrepant
to the original received less attention than those that
were moderately similar or moderately discrepant.
• There are instances when infants prefer similar, not
novel, stimuli.
Psychological Stimulus Characteristics
• Generally, young infants prefer familiar stimuli, then
show no preference, then they prefer novel stimuli.
• Takes time to create schemas.
The Development of Face Processing
• Infants prefer vertical, symmetrical stimuli with
curved lines making them well-suited to attend to
faces.
• A bias to human faces would make evolutionary
sense and would facilitate attachment.
• Johnson et al. (1991) showed newborns paddle
stimuli which resembled faces, did not resemble
faces, or were blank.
The Development of Face Processing
• They presented these stimuli and moved them.
• Measured how much infants followed the stimuli by moving
their eyes and head.
• Following this paradigm, infants will show a preference for
face-like stimuli as early as 5 days of age.
The Development of Face Processing
• There is evidence that newborns may be able to
make discriminations between faces.
– Look longer at photos of their mothers than at photos of
other women (Bushnell et al., 1989) .
– They will alter sucking rate to see a photo of their mother
over another woman (Walton et al., 1992).
• Babies also show a preference for attractive faces
over unattractive faces (Langlois, 1987).
– Infants as young as two months will look longer at
attractive faces as opposed to unattractive faces.
The Development of Face Processing
• This might be because infants prefer upright,
curvilinear, symmetrical stimuli.
– It might be evolutionary since symmetry is a sign of health.
– Important for mate selection.
Auditory Development
• Hearing develops substantially in the first year, but is
not adultlike until about 10 years of age.
• Auditory perception is well-developed in the
newborns, particularly at high frequencies.
• DeCasper and Fifer (1980) found that 1- to 3-day-old
infants will alter their sucking rates to hear a tape
recording of their mothers as opposed to that of a
stranger.
Auditory Development
• DeCasper’s and Spence’s (1986) earlier research on
infants and sucking rate shows that they’re capable
of auditory learning prenatally.
• Studies measuring heart rate in response to familiar
and novel passages during the third trimester reveals
similar findings.
Speech Perception
• Infants can perceive most and perhaps all phonemes
found in all human languages.
– Phonemes: the basic units of speech.
• Eimas et al. (1971) repeatedly presented 1-montholds with a phoneme along the ba/pa continuum
until they showed a decrease in sucking rate (i.e.,
habituation).
Speech Perception
• Infants would show an increase in sucking rate
(dishabituate) if a phoneme was presented on
the other side of the ba/pa continuum.
• They use the same dividing line as older
children and adults.
Speech Perception
• Infants can make phoneme discriminations that
adults can not make.
• They can make discriminations in foreign languages
that adults can not make.
• However, this ability is quickly lost.
• At the same time, they are able to make increasingly
fine discriminations between phonemes in their
mother tongue (Kuhl et al., 2006).
Speech Perception
• This language flexibility is probably not adaptive
after a certain age.
– The brain should dedicate neurons to processing sounds in
the language its exposed to.
• Infants are able to recognize frequently heard sound
patterns at least by 4.5 months of age.
Violation-of-Expectation Method
• An infant’s reaction to an unexpected event is used to infer
what he/she knows.
• Uses infants’ looking behavior along with preference-fornovelty and habituation/dishabituation procedures.
• If what they see differs from what they expect, they should
look longer at this event.
Core Knowledge
• Infants possess core knowledge.
• They are born with a small set of distinct systems of
knowledge that have been shaped by natural
selection and upon which new skills and belief
systems are built.
• According to Spelke, there are three core knowledge
systems in infancy.
– Object representation, knowledge of people and actions,
ability to represent numbers or quantities.
Object Representation
• What infants know about the nature of objects.
• Object Constancy: Knowledge that an object remains the
same despite changes in how it is viewed.
– As an object gets closer, its retinal image gets larger
– We perceive it as getting “closer” rather than “larger”
• Newborns possess object constancy (Slater, Mattock, &
Brown, 1990).
• Infants were habituated to an object of a particular size.
Object Constancy
• Then shown one of two objects.
– Same object as seen at a different distance
– New object of a different size (yet retinal image is the
same).
– Infants remain habituated to the first object
Object Continuity and Cohesion
• Individual objects are seen as cohesive wholes with
distinct boundaries.
• Kellman and Spelke (1983) tested this with 4 montholds.
– Habituated to a stick moving back and forth
underneath a bar
– Tested with one stick or two stick displays
Condition 1
Habituation + 2 Object Test
Condition 1
Habituation + 2 Object Test
Condition 1
Habituation + 2 Object Test
Condition 2
Habituation + 1 Object Test
Condition 1
Habituation + 2 Object Test
Recover (dishabituate):
unexpected
Condition 2
Habituation + 1 Object Test
Don’t recover (dishabituate):
expected
Object Continuity and Cohesion
• 4-mo dishabituate to condition 1 but not condition 2
– But only if the object was moving
– Not if stationary
• 2- and 4-month-olds infer object unity in some
situations, but not in others.
• Newborns don’t appear to be born with
continuation.
Objects Continuity and Cohesion
• Baillargeon et al. (1995) investigated whether infants
understood the notion of support.
Objects Continuity and Cohesion
• 3-month-old infants weren’t surprised with the impossible
outcome.
• 6.5-month-olds expect the box to fall unless a large portion
maintains contact with the platform.
Objects Continuity and Cohesion
• Initially, infants believe that any contact between two
objects is enough for one to support the other.
• They progress until they reach an adult-like concept
of support.
• However, 2-year-old children will fail on a similar task
(see Hood et al., 2000; p. 215).
Objects Continuity and Cohesion
• Baillargeon proposed that infants possess the
principle of persistence.
• Objects exist continuously, remain cohesive, and
retain their individual properties.
• Yet this notion is underdeveloped at first, and later
becomes enriched with experience.
Objects Continuity and Cohesion
Familiarize:
(a)
(b)
(c)
Hood et al. (2000) study with 2- and 2.5-yr-olds
Test event: Where is
The ball?
Objects are Continuous, Solid, and Require Support
• Perhaps the difference in the nature of the tasks
explain these findings.
• That is, 2-year-olds need to demonstrate an explicit
understanding of spatial relations, whereas infants
need only display an implicit understanding.
Object Permanence
• The understanding that objects continue to exist
when they can not be perceived.
• According to Piaget, until 4 months of age objects
exist merely as extensions of their perceptions or
actions upon them.
• At 4 months, they will retrieve an object that is
partly hidden.
– Will not search for a completely hidden toy.
Object Permanence
• At 8 months, infants will retrieve a completely
hidden toy.
• Yet, they can not solve the A not B task.
• At 12 months, they can solve A not B, but cannot do
invisible displacement.
– Object is hidden in one container and then in another
container out of the vision of the observer.
– Need to mentally represent objects.
A New Look at Object Permanence
• Infants as young as 3.5 months possess more
knowledge than Piaget proposed.
– Some believe object permanence is innate.
• Baillargeon (1987) studied this using the violation-ofexpectation method (p 140).
• 3.5- and 4.5-month-old infants were habituated to a
screen moving 180° in space.
• A block was then placed behind the screen to
produce an impossible event.
A New Look at Object Permanence
A New Look at Object Permanence
• No differences were found for the control
condition.
• In the experimental condition, infants looked
longer at the impossible event.
• They believed the block continued to exist when
out of their sight and were surprised when the
screen dropped.
• They have knowledge of object permanence and
that one solid can’t pass through another.
A New Look at Object Permanence
• Newcombe et al. (1999) buried a toy in a
sandbox in front of 5-month-olds, and then dug it
out 10 sec later.
• After multiple trials, the object was dug out from
6 inches away.
• Infants looked significantly longer at these trick
trials.
• They weren’t surprised when a different object
was dug out of this location.
A New Look at Object Permanence
• Even when using the traditional A not B
task, infants as young as 7.5 months will
search correctly on B trials.
– The delay must be short.
– Thus, inhibition is likely involved.
Early Number Concepts
• Numerosity: the ability to determine the number
of items in a set without counting.
• Ordinality: a basic understanding of more than
or less than.
• Infants as young as 10 months can distinguish
between two boxes containing different amounts
of crackers.
Early Number Concepts
• Infants as young as 6 months of age can tell the
difference between arrays, but the ratio must be
relatively large.
Simple Arithmetic
• Wynn has used the violation-ofexpectations method to show that infants
can add and subtract small quantities.
Simple Arithmetic
Simple Arithmetic
• But, it’s not clear exactly what’s going on here.
• Maybe infants are not responding to number, but
the total amount of substance present.
Arguments Against Core Knowledge
• Bogartz et al (1998) argue that it is not
necessary to use innate knowledge of objects to
explain infants’ looking behavior.
• Infants acquire object knowledge through
perceptual experience.
Arguments Against Core Knowledge
• This perceptual processing produces the looking
patterns others interpret as innate knowledge.
• Perceptual processing takes time.
• Novel events (impossible events) simply take
longer to process because initial encoding of the
stimuli needs to be done.
• This takes time and results in longer looking
times.
Category Representation
• Babies show preferences indicating that they have
some form of visual memory.
• This implies that they form categories.
• Items from similar categories are treated as being
the same.
Measuring Categorization
• Often measured using habituation/dishabituation.
• Stimuli are varied slightly during habituation trials.
• Eg., when habituating infants to faces, multiple faces
can be used.
– Infants will still show decrease in looking times.
• Cohen and Strauss (1979) did this with 30-week-olds.
– Infants can form a human face category.
– Human face is distinct from other perceptual categories.
Measuring Categorization
• Infants as young as 3 months can form categories
(see Eimas and Quinn, pp 147-8).
• But do these categories exist when infants enter the
lab?
• Or can infants merely distinguish the physical
features necessary to discover the categories in the
experimenters’ minds?
– It’s probably a little of both.
The Structure of Infants Categories
• Category Prototype: An abstract representation of a
category. A best example of a category.
• Infants appear to form category prototypes
– See Roberts and Horowitz, p 149.
– Infants will form a category for the concept of birds when
habituated to highly typical exemplars.
– The same is not the case when atypical exemplars are
used.