Psychological aspect

1. Perceptual Development
Chapter 5 OBJECTIVES:
What senses do newborn babies have?
Do their senses work like adults?
How do Infants perceive the world?

2. The Senses begin to function
early in life. But how can we
actually know what an infant
senses?
Since infants can’t tell us, researchers have
devised ways to find out.

3. Sensation
To understand what an infant can sense
researchers often present two stimuli and
record the baby’s response.
‐ For example a baby is given a sweet tasting
substance and a sour tasting substance
If the baby consistently responds
differently to the two stimuli then the infant
must be able to distinguish between them.

4. A technique called Habituation is
often used in researching infant
preference
This is the process of getting used to
something.
Click on the baby to view a video clip
(also provided in your textbook DVD)

5. Can infants use their senses
like adults?
NO, we do not arrive with all of our
senses fully functioning. This is yet
another area that will develop and mature
with the infant.

6. Smell
Infants have a keen sense of smell and
respond positively to pleasant smells and
negatively to unpleasant smells (Menella,
1997).
‐ Honey, vanilla, strawberry, or chocolate:
relaxed, produces a contented-looking facial
expression
‐ Rotten eggs, fish, or ammonia produce exactly
what you might expect…infants frown,
grimace or turn away

7. Did you know…
Young infants recognize familiar odors
Newborns will turn toward of a pad that is:
‐ Saturated with their own amniotic fluid
‐ Saturated with their own mother’s milk or
her perfume (Porter & Winburg, 1999).
‐ Isn’t that amazing?

8. Taste
Newborns also have a highly developed
sense of taste. They can differentiate
salty, sour, bitter & sweet tastes
(Rosenstein, 1997).
Do you think infant’s have a favorite
taste?

9. Taste
Most infants seem to have a “sweet
tooth”.
‐ Infants will nurse more after their mother
has consumed a sweet-tasting substance
like vanilla (Menalla, 1997)
Newborns prefer sweet. However, at 4
months, infants will have a salty
preference
‐ They will start liking salt which was aversive

10. Touch
Newborns are sensitive to touch, many
areas of the newborn’s body respond
reflexively when touched
What do YOU think?
‐ If babies react to touch, do they experience
pain?

11. OUCH!?
The infant’s nervous
system is definitely capable
of experiencing pain
Receptors for pain in the
skin are just as plentiful in
infants as they are in
adults.
Babies behavior in
response to a pain-
provoking stimulus
suggests that they

12. What Do Infants See?
Vision is the least mature of all the
senses at birth because the fetus has
nothing to look at, so visual
connections in the brain can’t form
until birth.

13. Newborn visual acuity is 20/400 to 20/800
‐ 20/200 or worse defines legal blindness in
adults
Newborn visual acuity is 20/400 to 20/800
‐ 20/200 or worse defines legal blindness in
adults
By 6 months, infant visual acuity is 20/25
By 1 year, infant visual acuity is at adult levels
(20/20)
Click on the
baby to see
like an infant!

14. What is the clarity of infant vision
and how can we measure it?
Visual acuity is defined as the smallest
pattern that can distinguished
dependably.
‐ Infants prefer to look at patterned stimuli
instead of plain, non-patterned stimuli
To estimate an infant’s visual acuity, we
pair gray squares with squares that differ
in the width of their stripes.

15. When the infant looks at the two stimuli equally
long, it indicates they are no longer able to
distinguish the stripes of the patterned stimulus
from the solid gray square

16. At birth, infants’ sensitivity to fine, high-spatial
frequency gratings, like their acuity, is very poor
but improves steadily with age.

17. Light Sensitivity
Newborns begin to see the world not only with
greater acuity but also in color
At birth, infants have the greatest sensitivity to
intermediate wavelengths (yellow/green) and
less to short (blue/violet) or long (red/orange).

18. Newborns can perceive few colors, but By
3-4 months newborns are able to see the
full range of colors (Kellman, 1998).
‐ In fact, by 3-4 months infants have color
perception similar to adults (Adams, 1995).

19. At 1 week, the infant
can discriminate the
desaturated red from
gray
At 2 months, the infant
can discriminate the
desaturated blue from
gray

20. What do babies hear?
Hearing is the most mature sense at birth. In fact,
some sounds trigger reflexes even without
conscious perception.
‐ The fetus most likely heard these sounds in the womb
during last trimester
Sudden sounds startle babies-making them cry,
some rhythmic sounds, like a heartbeat/lullaby
put a baby to sleep.
Yes, infants in first days of life, turn their head
toward source of sounds and they can
distinguish voices, language, and rhythm.

21. Auditory Threshold
The fetus can hear in utero at 7-8 months,
so it is no surprise that newborns respond
to auditory stimuli but, do infants hear as
well as adults??
No they cannot. The Auditory threshold
refers to the quietest sound that a person
can hear.
The quietest sound an newborn responds
to is about 4 times louder than the quietest
sound an adult responds to.

22. Do infants hear like adults?
Research reveals that adults hear better than
infants because adults can hear some very quiet
sounds that infants cannot.
Research shows that infants hear sounds best
that have high pitches in the range of human
speech (Jusczyk, 1995).
‐ Can differentiate vowels from consonants
‐ At 4 months, can recognize own name
Infants also use sound to locate objects and
estimate distance.

23. How DO Infants
Perceive the World?

24. Perceptual Constancies
An important part of perceiving objects is
that the same object can look very
different
Infants master size constancy very early
on
‐ They recognize that an object remains
the same size despite its distance from
the observer

25. You can recognize that the
woman in this picture has not
shrunk…she is just farther away

26. Depth Perception
Infants are not born with depth perception,
it must develop. The images on the back of
our eyes are flat and 2-dimensional
To create a 3-D view of the world, the brain
combines information from the separate
images of the two eyes, retinal disparity
Visual experience along with development
in the brain lead to the emergence of
binocular depth perception around 3-5

27. Perception in infants
Can infants process
sensory information
accurately?
This was a question
posed by Walk and
Gibson in 1960
The Visual cliff
experiment was
designed to provide the
illusion of a sudden
drop off between one
horizontal surface and

28. Face Recognition
Infants enjoy looking at faces, a
preference that may reflect innate
attraction to faces, or a fact that faces
may attract infant’s attention.
At birth, infants are attracted to the
borders of objects When looking at a
human face
‐ a newborn will pay more attention to the
hairline or the edge of the face (even though
the newborn can see the features of the face)

29. By 2 months of age, infants begin to attend to the
internal features of the face – such as the nose and
mouth
By 3 months of age, infants focus almost entirely on
the interior of the face, particularly on the eyes and
lips. At this age, infants can tell the difference
between mother’s face and a stranger’s face.
Theorist’s believe that infants are attracted to
human faces because faces have stimuli that move
(eyes and lips) and stimuli with dark and light
contrast (the eyes, lips and teeth).

30. Infants readily look at faces, a
preference that may reflect an
innate attraction to faces or the
fact that faces have many
properties that attract infant’s
attention

31. Perceiving Faces
Infants are particularly interested in
looking at human faces, but focus on
different areas of the face depending on
their age

32. Motor Development

33. Test your Knowledge
Pedal a tricycle
Sit without support
Walk unassisted
Stand on one foot
for 10 seconds
Roll over
Kick a ball forward
Crawl
At what age can at least 50% of children begin to
display each of these behaviors?

34. How Did You Do?
Pedal a tricycle
2 years, 90% by 3years
Sit without support
6 Months, 90% by 7-8
months.
Walk unassisted
12 Months, 90% by 14
months.
Stand on one foot for 10
seconds
4 ½ years
Roll over
3 months, 90% by 5
months.
Kick a ball forward
20 months, 90% by 9
months.
Crawl
7 months, 90% by 9
months

35. Motor Milestones
50 percent 90 percent
Roll over 3.2 months 5.4 months
Grasp rattle 3.3 months 3.9 months
Sit without support 5.9 months 6.8 months
Stand holding on 7.2 months 8.5 months
Pincer grasp 8.2 months 10.2 months
Crawl 7.0 months 9.0 months
Stand alone 11.5 months 13.7 months
Walks well 12.3 months 14.9 months
Build tower (2 cubes) 14.8 months 20.6 months
Walk steps 16.6 months 21.6 months
Jump in place 23.8 months 2.4 years
Copy circle 3.4 years 4.0 years

36. Head Control
At birth infants can turn their heads from
side to side while lying on their backs
By 2-3 months they can lift their heads
while lying on their stomachs
By 4 months infants can keep heads
erect while being held or supported in a
sitting position

37. Before you walk, you must learn
to….
At around 6-8 months, infants become
capable of self-locomotion
To master walking (around 13-14 months),
infants must acquire distinct skills
‐ Standing upright
‐ Maintaining balance
‐ Stepping alternately
‐ Using perceptual information to evaluate
surfaces

38. Crawling
Begins as belly-crawling
‐ The “inchworm belly-flop” style
Most belly crawlers then shift to hands-and-
knees, or in some cases, hands-and-feet
Some infants will adopt a different style of
locomotion in place of crawling such as bottom-
shuffling while some infants skip crawling
altogether
Due to the “back-to-sleep” movement, infants
spend less time on their tummies which may limit
their opportunity to learn how to propel

39. Belly-crawling
Hands-and-feet crawling
Hands-and-knees crawling

40. Walking – Stepping
Children do not step spontaneously until
approximately 10 months because they
must be able to stand in order to step
Maintaining balance when transferring
weight from foot to foot seems to be key
Thelen and Ulrich (1991) found that 6-
and 7-month-olds, if held upright by an
adult, could demonstrate the mature
pattern of walking of alternating steps on a
treadmill

41. Gross motor skills
Emerge directly from reflexes.
These are physical abilities involving
large body movements and large muscle
groups such as walking and jumping.
Involve the movement of the entire body-
‐ Rolling over, standing, walking climbing,
running

42. Fine Motor Skills
After infancy fine motor skills progress
rapidly and older children become more
dexterous because these movements
involve the use of small muscle groups
These consist of small body movements,
especially of the hands and fingers.
‐ such as drawing, writing your name, picking
up a coin, buttoning or zipping a coat.

43. Handedness
Young babies reach for objects without a
preference for one hand over the other
The preference for one hand over the other
becomes stronger and more consistent during
preschool years
‐ By the time children are ready to enter kindergarten,
handedness is well established and very difficult to
reverse
Handedness is determined by heredity and
environmental factors