Presentation on theme: "Perceptual Development"— Presentation transcript:
1Perceptual Development Chapter 5 OBJECTIVES:What senses do newborn babies have?Do their senses work like adults?How do Infants perceive the world?
2The Senses begin to function early in life 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.
3SensationTo 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 substanceIf the baby consistently responds differently to the two stimuli then the infant must be able to distinguish between them.
4A 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)
5Can 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.
6SmellInfants 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 expressionRotten eggs, fish, or ammonia produce exactly what you might expect…infants frown, grimace or turn awayNewborns can differentiate salty, sour, bitter, and sweet:Infants prefer sweet infants will nurse more after their mother has consumed a sweet-tasting substance like vanillaNewborns prefer sweet. However, at 4 months, infants will have a salty preference – they will start liking salt which was aversive to them as newborns.
7Did you know… Young infants recognize familiar odors Newborns will turn toward of a pad that is:Saturated with their own amniotic fluidSaturated with their own mother’s milk or her perfume (Porter & Winburg, 1999).Isn’t that amazing?
8TasteNewborns 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?
9Taste 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 preferenceThey will start liking salt which was aversive to them as newborns.
10TouchNewborns are sensitive to touch, many areas of the newborn’s body respond reflexively when touchedWhat do YOU think?If babies react to touch, do they experience pain?Babies behavior in response to a pain-provoking stimulus suggest that they experience painPain expression:Lowering of eyebrowsPursing of lipsOpening mouth to cryShowing signs of agitation – moving arms, hands, and legs
11OUCH!?The infant’s nervous system is definitely capable of experiencing painReceptors 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 experience pain.
12What 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.Lack of visual acuity is due to the lack of cone developmentAcuity improves as cones elongate and migrate – they move closer together to form the fovea
13Newborn visual acuity is 20/400 to 20/800 20/200 or worse defines legal blindness in adultsBy 6 months, infant visual acuity is 20/25By 1 year, infant visual acuity is at adult levels (20/20)Click on the baby to see like an infant!
14What 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 stimuliTo estimate an infant’s visual acuity, we pair gray squares with squares that differ in the width of their stripes.By measuring the width of the stripes and their distance from the infant’s eyes, we can estimate acuity – being able to detect thinner stripes indicates better acuity
15When 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 squareThere comes a point at which the black and white stripes become so fine that they simple blend together and appear gray – just like the solid gray pattern
16As for acuity:The improvements in contrast sensitivity is due to the elongation and tighter packing of cones in the retina and is associated with development of the visual cortexImproving contrast sensitivity:This picture provides a gray scale representation of how an infant might see contrast information at 3, 6, and 9 months compared to an adult. The infant is increasingly able to see fine detail, low contrast elements in their environmentAt birth, infants’ sensitivity to fine, high-spatial frequency gratings, like their acuity, is very poor but improves steadily with age.
17Light SensitivityNewborns begin to see the world not only with greater acuity but also in colorAt birth, infants have the greatest sensitivity to intermediate wavelengths (yellow/green) and less to short (blue/violet) or long (red/orange).
18Newborns 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).
19At 1 week, the infant can discriminate the desaturated red from gray At 2 months, the infant can discriminate the desaturated blue from grayAt 1 week, the infant is likely to perceive the desaturated red to be different from the gray. However, a difference between the desaturated blue and the gray is not likely to be perceived until about 2 months
20What 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 trimesterSudden 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.
21Auditory ThresholdThe 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.Hearing is not at adult levels until 5-8 years of ageSigns of hearing impairment:Infant never responds to sudden, loud soundsInfant has repeated ear infectionsInfant does not turn head in direction of sounds by 4-5 monthsInfant does not respond to his/her own name by 8-9 monthsInfant does not imitate speech sounds and simple words by 12 months
22Do 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 consonantsAt 4 months, can recognize own nameInfants also use sound to locate objects and estimate distance.
24Perceptual Constancies An important part of perceiving objects is that the same object can look very differentInfants master size constancy very early onThey recognize that an object remains the same size despite its distance from the observer
25You can recognize that the woman in this picture has not shrunk…she is just farther away
26Depth PerceptionInfants are not born with depth perception, it must develop. The images on the back of our eyes are flat and 2-dimensionalTo create a 3-D view of the world, the brain combines information from the separate images of the two eyes, retinal disparityVisual experience along with development in the brain lead to the emergence of binocular depth perception around 3-5 months of age
27Perception in infantsCan infants process sensory information accurately?This was a question posed by Walk and Gibson in 1960The Visual cliff experiment was designed to provide the illusion of a sudden drop off between one horizontal surface and another
28Face RecognitionInfants 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 facea 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)
29By 2 months of age, infants begin to attend to the internal features of the face – such as the nose and mouthBy 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).
30Infants 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
31Perceiving FacesInfants are particularly interested in looking at human faces, but focus on different areas of the face depending on their age
33Test your KnowledgeAt what age can at least 50% of children begin to display each of these behaviors?Pedal a tricycleSit without supportWalk unassistedStand on one foot for 10 secondsRoll overKick a ball forwardCrawl2 years (90% by 3 years)5-6 months (90% by 7-8 months)11-12 months (90% by months)4.5 years3 months (90% by 5 months)20 months (90% by 2.5 years)7 months (90% by 9 months)
34How Did You Do? Roll over 3 months, 90% by 5 months. Pedal a tricycle2 years, 90% by 3yearsSit without support6 Months, 90% by 7-8 months.Walk unassisted12 Months, 90% by 14 months.Stand on one foot for 10 seconds4 ½ yearsRoll over3 months, 90% by 5 months.Kick a ball forward20 months, 90% by 9 months.Crawl7 months, 90% by 9 months
35Motor Milestones 50 percent 90 percent Roll over 3.2 months 5.4 months Grasp rattle3.3 months3.9 monthsSit without support5.9 months6.8 monthsStand holding on7.2 months8.5 monthsPincer grasp8.2 months10.2 monthsCrawl7.0 months9.0 monthsStand alone11.5 months13.7 monthsWalks well12.3 months14.9 monthsBuild tower (2 cubes)14.8 months20.6 monthsWalk steps16.6 months21.6 monthsJump in place23.8 months2.4 yearsCopy circle3.4 years4.0 yearsRolls from side to back – average at 2 months, 90% at 5 monthsRolls from back to side – average at 4.5 months, 90% 7 monthsPulls to stand – average at 8 months, 90% as 12 monthsWalks on tiptoe – average at 25 months, 90% at 30 months
36Head ControlAt birth infants can turn their heads from side to side while lying on their backsBy 2-3 months they can lift their heads while lying on their stomachsBy 4 months infants can keep heads erect while being held or supported in a sitting positionHold chin up while on stomach: around 1 monthHold chest up while on stomach: around 2 months
37Before you walk, you must learn to…. At around 6-8 months, infants become capable of self-locomotionTo master walking (around months), infants must acquire distinct skillsStanding uprightMaintaining balanceStepping alternatelyUsing perceptual information to evaluate surfaces
38Crawling Begins as belly-crawling The “inchworm belly-flop” styleMost belly crawlers then shift to hands-and-knees, or in some cases, hands-and-feetSome infants will adopt a different style of locomotion in place of crawling such as bottom-shuffling while some infants skip crawling altogetherDue to the “back-to-sleep” movement, infants spend less time on their tummies which may limit their opportunity to learn how to propel themselvesStart around 6 months:Over the next couple months, the infant learns to move confidently from the sitting position to being on all foursThe infant realizes that he/she can rock backAround 9-10 months:Pushing off with knees gives the boost needed to get mobileWith practice, the infant will learn to go from sitting to crawlingWith practice, infant will learn “cross-crawling” – moving opposite hand and leg rather than arm and leg from same side of the bodyBy 12 months – competent crawler
40Walking – SteppingChildren do not step spontaneously until approximately 10 months because they must be able to stand in order to stepMaintaining balance when transferring weight from foot to foot seems to be keyThelen 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 treadmillCalled a toddler around months: stands alone and can “toddle”
41Gross 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
42Fine Motor SkillsAfter infancy fine motor skills progress rapidly and older children become more dexterous because these movements involve the use of small muscle groupsThese 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.
43HandednessYoung babies reach for objects without a preference for one hand over the otherThe preference for one hand over the other becomes stronger and more consistent during preschool yearsBy the time children are ready to enter kindergarten, handedness is well established and very difficult to reverseHandedness is determined by heredity and environmental factorsApproximately 10% of children write left-handedTwo right-handed parents will have right-hand children. If a parent is left-hand then there is a possibility for a left-handed childCulture:School desks, scissors, and can openers are designed for right-handed peopleIslam religion dictates that the left hand is unclean – the religion forbids people from using their left hand to eat or to greet othersWriting with the left hand is cultural taboo in China