Developmental Psychology Chapter 7.pdf

7 Andrea Nord Early Cognitive Foundations: Sensation, Perception, and...

7 Andrea Nord Early Cognitive Foundations: Sensation, Perception, and Learning I magine that you are a neonate, only 5 to 10 minutes old, who has just been sponged, swaddled, and handed to your mother. As your eyes meet hers, she smiles and says, “Hi there, sweetie,” in a high-pitched voice as she moves her head closer and gently strokes your cheek. What would you make of all this sensory input? How would you interpret these experiences? Developmentalists are careful to distinguish between sensation and per- sensation ception. Sensation is the process by which sensory receptor neurons detect detection of stimuli by the sensory information and transmit it to the brain. Clearly, neonates “sense” the envi- receptors and transmission of this ronment. They gaze at interesting sights, react to sounds, tastes, and odours, information to the brain. and are likely to cry up a storm when poked by a needle for a blood test. But perception do they “make sense” of these sensations? Perception is the interpretation process by which we categorize and of sensory input: recognizing what you see, understanding what is said to interpret sensory input. you, or knowing that the odour you’ve detected is fresh-baked bread. Are newborns capable of drawing any such inferences? Do they perceive the world, or merely sense it? We might also wonder whether very young infants can associate their sen- sations with particular outcomes. When, for example, might a baby first asso- ciate his or her mother’s breast with milk and come to view Mom as a valuable commodity who eliminates hunger and other kinds of distress? Are infants capable of modifying their behaviour to persuade Mom to attend to them? These are questions of learning—the process by which our behaviours change as a result of experience. Maybe we should start with a more practical question. Why should we concern ourselves with the development of sensation, perception, and learning? Perhaps because these three processes are at the heart of human functioning. Virtually everything we do depends on our interpretations of and reactions to sensory input—the things we experience. So the study of early sensory, percep- tual, and learning capabilities can provide some fundamental clues about how we gain knowledge of reality. 178 NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Chapter 7 | Early Cognitive Foundations: Sensation, Perception, and Learning 179 ‫اﻟﺧﻼﻓﺎت‬ Early Controversies about Sensory and Perceptual Development Nature versus Nurture Long before anyone conducted any experiments to decide the issue, philosophers were already debating what newborns might sense and perceive. Empiricist philosophers believed that an infant was a tabula rasa (blank slate) who must learn to interpret sensa- tions. In fact, William James (1890) argued that all senses are integrated at birth, so that sights, sounds, and other sensory inputs combine to present the newborn with a “blooming, buzzing confusion.” By contrast, nativist philosophers such as René Descartes (1638/1965) and Immanuel Kant (1781/1958) took the nature side of the nature/nurture issue, arguing that many basic perceptual abilities are innate. For example, they believed that we are born with an understanding of spatial relations. Presumably, infants do not need to learn that receding objects appear smaller or that approaching objects seem to increase in size; these were enrichment theory said to be adaptive perceptual understandings that were built into the human nervous theory specifying that we must add to sensory stimulation by drawing on system over the course of evolution. stored knowledge in order to perceive Today’s developmentalists take less extreme stands on this nature/nurture issue. a meaningful world. Although most would concede that babies see some order in their surroundings from day 1, differentiation theory they recognize that the perceptual world of a human neonate is rather limited and that theory specifying that perception both maturational processes and experience contribute to the growth of perceptual involves detecting distinctive features awareness (Smith & Katz, 1996). or cues that are contained in the sensory stimulation we receive. distinctive features characteristics of a stimulus that Enrichment versus Differentiation remain constant; dimensions on Now consider a second issue that early philosophers debated: is the coherent reality that which two or more objects differ and can be discriminated (sometimes we experience through the senses simply “out there” to be detected? Or, rather, do we called invariances or invariant construct our own interpretations of that reality based on our experiences? This issue is features). hotly contested in two modern theories of perceptual development: enrichment theory and differentiation theory. Both of these theories argue that there is an objective reality out there to which we respond. However, enrichment theory (Piaget, 1954, 1960) claims that sensory stimulation is often fragmented or confusing. To interpret such ambiguous input, we use our available cognitive schemes to add to or enrich it. You have probably heard radio contests in which people call in to identify a song after hearing only a note or two. According to enrichment theory, contest winners can answer correctly because they draw on their memory of musical passages to add to what they have just heard and infer what the song must be. In sum, the enrichment position is that cognition Figure 7.1 Expectations affect enriches sensory experience. Our knowledge helps us construct meaning from the sen- perception. If told to name the animal in this drawing, you would sory stimulation we receive (see Figure 7.1). likely see a rat with large ears and its By contrast, Eleanor Gibson’s (1969, 1987, 1992) differentiation theory argues that tail circling in front of the body. But sensory stimulation provides all we need to interpret our experiences. Our task as fledg- if you saw the drawing amid other ling perceivers is simply to detect the differentiating information, or distinctive features, drawings of faces, you would likely that enable us to discriminate one form of experience from another. Consider that many perceive an elderly bald man with 2-year-olds are apt to say “doggie” whenever they see a dog, a cat, or some other small, glasses (see him?). So, as Piaget and furry animal. They have not yet noticed the critical differences in sizes, shapes, manner- other enrichment theorists have isms, or sounds that enable us to discriminate these creatures. Once children master this argued, cognition does affect our perceptual learning, however, their continuing quest for differentiating information may interpretation of sensory stimulation. soon enable them to distinguish long-nosed collies from pug-faced boxers or spotted Source: Adapted from “‘Perceptual Set’ in Dalmatians, although they understand that all these animals are properly labelled dogs. Young Children,” by H. W. Reese, 1963, Child Development, 34, pp. 151–59. Gibson’s point is that the information needed to make these finer distinctions was always Copyright © 1963 by the Society for there in the animals themselves, and that the children’s perceptual capabilities blossom as Research in Child Development. they detect these distinctive features. NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  180 Part Three | Language, Learning, and Cognitive Development So which theory is correct? Maybe both of them are. The research we will review in this chapter provides ample support for Gibson’s view: children do get better at detecting information already contained in their sensory inputs. Yet Piaget’s view that existing knowledge provides a basis for interpreting our sensations is also well documented, as we will see in examining Piaget’s theory of cognitive development in Chapter 8. Research Methods Used to Study the Infant’s Sensory and Perceptual Experiences In the early 1900s, many medical texts claimed that human infants were functionally blind, deaf, and impervious to pain for several days after birth. Babies were believed to be unprepared to extract any “meaning” from the world around them. Today, we know otherwise. Why the change in views? It is not that babies have become any more capable or any smarter. Instead, researchers have gotten smarter and have developed some inge- nious research methods for understanding what nonverbal infants can sense and perceive (Bornstein, Arterberry, & Mash, 2015). Let’s briefly discuss some of these techniques. The Preference Method preference method The preference method is a simple procedure in which at least two stimuli are method used to gain information presented simultaneously to see whether infants will attend more to one of them than about infants’ perceptual abilities the other(s) (Houston-Price & Nakai, 2004; Dunn & Bremnar, 2017). This approach by presenting two (or more) stimuli and observing which stimulus the became popular during the early 1960s after Robert Fantz used it to determine whether infant prefers. very young infants could discriminate visual patterns (e.g., faces, concentric circles, newsprint, and unpatterned disks). Babies were placed on their backs in a looking habituation decrease in response to a stimulus chamber (see Figure 7.2) and shown two or more stimuli. An observer located above that has become familiar through the looking chamber then recorded the amount of time the infant gazed at each of the repetition. visual patterns. If the infant looked longer at one target than the other, it was assumed that he or she preferred that pattern. Fantz’s early results were clear. Newborns could easily discriminate (or tell the differ- ence between) visual forms, and they preferred to look at patterned stimuli such as faces or concentric circles rather than at unpatterned disks. Apparently, the ability to detect and discriminate pat- terns is innate (Fantz, 1963). The preference method, with a modern setup (see Figure 7.3), continues to be used to study infants’ abilities such as numeracy (McCrink & Wynn, 2004). The preference method has one major short- coming. If an infant shows no preferences among the target stimuli, it is not clear whether she or he failed to discriminate them or simply found them equally interesting. Fortunately, each of the fol- lowing methods can resolve this ambiguity. The Habituation Method Perhaps the most popular strategy for measuring infant sensory and perceptual capabilities is the habitu- ation method. Habituation is the process in which a repeated stimulus becomes so familiar that responses Chris Linton initially associated with it (e.g., head or eye move- ments, changes in respiration or heart rate) no longer Figure 7.2 The looking chamber that Fantz used to study infants’ occur. Thus, habituation is a simple form of learning. visual preferences. As infants stop responding to familiar stimuli, they are NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Chapter 7 | Early Cognitive Foundations: Sensation, Perception, and Learning 181 telling us that they recognize them as old hat—something that they have experienced before (Aslin, 2007). For this reason, the habituation method is also referred to as a “familiarization–novelty” procedure (Bornstein & Colombo, 2012). To test an infant’s ability to discriminate two stimuli that differ in some way, the investigator first presents one of the stimuli until the infant stops attending or otherwise responding to it (habituates). Then the second stimulus is presented. If the infant discriminates this second stimulus from the first, he or she will dishabituate—that is, attend closely to it while showing a change in respiration or heart rate. If the infant fails to react, it is assumed that the differences between the two stimuli were too subtle for him or her to detect. Joanne Lee Because babies habituate and dishabituate to so many different kinds of stimulation—sights, sounds, odours, tastes, and touches—the habituation method is very useful for assessing their sensory and Figure 7.3 A modern version of the preference method to study infants’ numeracy ability. perceptual capabilities. However, distinguishing between habituation and preference effects can be tricky (Houston-Price & Nakai, 2004). Infants display dishabituation preference when they are familiar with—but not too familiar with—a stimulus. When pre- an increase in responsiveness that sented with two stimuli, initially infants show no preference—they don’t look at one toy, occurs when stimulation changes. person, and picture any more frequently than they look at the other. When one stimulus does capture their attention, they begin to look at it more often and, for a short time, when presented with this partially familiar stimulus and an unfamiliar stimulus, they will spend more time looking at the partially familiar stimulus. When they become thoroughly familiar with the original stimulus, they become ready to move on and will spend less time looking at the familiar stimulus than its unfamiliar partner (see Figure 7.4 for an example of this sequence of attentional events). To properly categorize infant looking behaviours, researchers must pay careful attention to the familiarization time line of each infant being tested (Houston-Price & Nakai, 2004). The High-Amplitude Sucking Method Most infants can exert enough control over their sucking behaviour to use it to show us what high-amplitude sucking method they can sense and to give us some idea of their likes and dislikes. The high-amplitude a method of assessing infants’ sucking method, which is appropriate for infants between birth and 4 months old, provides perceptual capabilities that capitalizes on the ability of infants to make interesting events last by varying Novel the rate at which they suck on a special pacifier. Preference None Familiar Familiarization time No preference Familiar No Novel preference preference preference Figure 7.4 A model of the effect of familiarization time on an infant’s preference for a novel versus familiar stimulus. Source: From Michael A. Hunter and Elinor W. Ames, A multifactor model of infant preferences for novel and familiar stimuli, Fig. 2, Advances in Infancy Research, Volume 5, Rovee-Collier, Lewis P. Lipsitt (eds.), 1988. NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  182 Part Three | Language, Learning, and Cognitive Development infants with a special pacifier containing electrical circuitry that enables them to exert some control over the sensory environment (see Figure 7.5; Jusczyk, 1985). After the researcher establishes an infant’s baseline sucking rate, the procedure begins. Whenever the infant sucks faster or harder than he or she did during the baseline observations (high-amplitude sucking), the infant trips the electrical circuit in the pacifier, thereby activating a slide pro- jector or tape recorder that introduces some kind of sensory stimulation. Should the infant detect this stimulation and find it interesting, she or he can make it last by displaying bursts of high-amplitude sucking. But once the infant’s interest wanes and her or his sucking returns to the baseline level, the stimulation stops. If the investigator then introduces a Figure 7.5 The high-amplitude sucking apparatus. second stimulus that elicits a dramatic increase in high-amplitude sucking, he or she could conclude that the infant has discriminated the second stimulus from the first. Source: Republished with permission of John Wiley, from C. Moon, This procedure can even be modified to let the infant tell us which of two stimuli is H. Lagercrantz, and P. Kuhl, “Language preferred. If we wanted to determine whether babies prefer their mother’s voice to that experienced in utero affects vowel of a female stranger, we could adjust the circuitry in the pacifier so that high-amplitude perception after birth: a two-country sucking activates the mother’s voice and low-amplitude (or no) sucking activates the study,” Acta Pædiatrica, Volume 102, other (DeCasper & Fifer, 1980). By then noting what the baby does, we could draw Issue 2. Copyright ©2012; permission conveyed through Copyright Clearance some inferences about which of these voices is preferred. Center, Inc. The Evoked Potentials Method Yet another way of determining what infants can sense or perceive is to present them with a stimulus and record their brain waves. Electrodes are placed on the infant’s scalp above those brain centres that process the kind of sensory information that the investi- gator is presenting (see Figure 7.6). This means that responses to visual stimuli are recorded from the back of the head, at a site above the occipital lobe, whereas responses to sounds are recorded from the side of the head, above the temporal lobe. If the infant senses the particular stimulus present, she will show a change in the patterning of her brain waves, or evoked potential triggered by the neural firing of cells. Stimuli that are evoked potential not detected will produce no changes in the brain’s electrical activity. This evoked a change in patterning of the brain potentials procedure tells us when the brain activity is occurring following the detection waves that indicates that an of a particular stimulus. It can even tell us whether infants can discriminate various sights individual detects (senses) a stimulus. or sounds, because two stimuli that are sensed as “different” produce different temporal patterns of electrical activity (Molfese, Fonaryova Key, Maguire, Dove, & Molfese, 2008). Brain Imaging Techniques While the evoked potentials method records the electrical activity in the brain, magnetoen- cephalography (MEG)—a neuroimaging technique—records the magnetic fields generated by the brain’s electric activity (Hamalainen, Hari, Ilmoniemi, Knuutila, & Lounasmaa, 1993) a few milliseconds after the neural firing. Unlike the evoked potentials method, this technique tells us when and where the brain’s activity is occurring when the newborn or infant detects particular stimuli, such as speech versus nonspeech (Imada, Yang, Cheour, Taulu, Ahonen, & Kuhl, 2006) or native speech versus non-native speech (Kuhl, Ramírez, Bosseler, Lin, & Imada, 2014). The most common neuroimaging technique is the functional magnetic resonance imaging (fMRI). Instead of recording the brain’s electric activity, this technique measures the amount of oxygen-rich blood flow to specific brain areas to replace the deoxygenated blood Oli Scarff/Getty Images used by these areas to detect a particular stimulus (Logothetis, Pauls, Augath, Trinath, & Oeltermann, 2001; Ogawa et al., 1992). This procedure tells us where the brain activity has occurred when an infant detects a particular stimulus, but not when the brain activity occurs, as it measures brain activity at the level of seconds (and not milliseconds). Not only are Figure 7.6 An EEG cap is used researchers curious to understand how specific brain areas are recruited to perform a function to place electrodes around the or behaviour, they are also interested in studying the brain areas that are recruited when baby’s head to record electrode infants are not doing anything. Hence, the fMRI procedure has been modified to what is activity at appropriate places on known as the resting-state fMRI to allow us to know more about how brain areas are function- the baby’s brain. ally organized in neonates and infants as they develop (Zhang, Shen, & Lin, 2018). NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Chapter 7 | Early Cognitive Foundations: Sensation, Perception, and Learning 183 Infant Sensory Capabilities Let’s now see what these creative methods have revealed about babies’ sensory and perceptual capabilities. How well do newborns sense their environments? Better, per- haps, than you might imagine. Let’s begin our exploration of infants’ sensory world by examining their auditory capabilities. Hearing Using the evoked potentials method, researchers have found that soft sounds that adults can hear must be made noticeably louder before a neonate can detect them (Aslin, Pisoni, & Jusczyk, 1983). In the first few hours of life, infants may hear about as well as an adult with a head cold. Their insensitivity to softer sounds could be due, in part, to fluids that have seeped into the inner ear during the birth process. Despite this minor limitation, habituation studies indicate that neonates are capable of discriminating sounds that differ in loudness, duration, direction, and frequency (Bower, 1982). They hear rather well indeed. And they impart meaning to sounds fairly early. For a sound to be detected, its intensity has to be about 40 to 55 decibels for 1-month-olds but only about 10 to 30 deci- bels for 6- to 12-month-olds (Olsho, Koch, Carter, Halpin, & Spetner, 1988; Trehub, Schneider, & Edman, 1980). At 4 to 6 months, infants react to a rapidly approaching auditory stimulus in the same way that they react to approaching visual stimuli: they blink in anticipation of a collision (Freiberg, Tually, & Crassini, 2001). Hearing is highly developed at birth; however, in their first 6 months of life, infants are not always consistent in responding to noises when noises are presented to them. In fact, many researchers have noted a U-shaped curve in studies where infants are pre- sented sounds and measured to see if they turn toward the sound. That means that infants at first always turn to the side where a sound is presented, then they seem to stop responding, and then at a later time start responding again. For example, when newborns are held facing the ceiling and hear a rattle sound on their left, they turn their heads to face the sound source (Muir & Field, 1979). By about 1 month of age, infants stop turning reliably toward off-centred sounds; they may even turn away. By 3 to 4 months of age, infants successfully orient toward the same sounds again. By 5 months of age, infants successfully use sound to localize objects in their environment (Neil, Chee-Ruiter, Schieer, Lewkowicz, & Shimojo, 2006). So what can explain this U-shaped curve for audi- tory localization? Muir and Hains (2004) suggest that neural maturation might be the best explanation. They argue that, similar to the stepping reflex (which appears at first as a reflex, disappears, and then returns later as a coordinated function controlled by another part of the now more mature brain), auditory localization may start out like a reflex and eventually come under the control of the mid- and forebrain structures as they mature. The work of Sandra Trehub and her colleagues at York University indicates that although a baby’s hearing improves over the first 4 to 6 months of life, even newborns are remarkably well prepared for such significant achievements as using voices to identify and discriminate their companions (Trehub, Schneider, Thorpe, & Judge, 1991). This is significant because hearing is especially important to development, as the research on hearing loss in Box 7.1 suggests. Reactions to Voices Young infants are particularly attentive to voices, especially high-pitched feminine voices (Ecklund-Flores & Turkewitz, 1996). But can they recognize their mother’s voice? Research by Anthony DeCasper and his associates (DeCasper & Fifer, 1980; DeCasper & Spence, 1986, 1991) reveals that newborns suck faster on a nipple to hear a recording of their mother’s voice than a recording of another woman. In fact, when mothers were instructed to recite a passage (e.g., portions of Dr. Seuss’s The Cat in the Hat) many times during the last 6 weeks of their pregnancies, their newborns sucked faster and NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it. 184 Part Three | Language, Learning, and Cognitive Development 7.1 FOCUS ON RESEARCH Causes and Consequences of Hearing Loss How important is hearing to human development? We gain some insight on this issue from the progress made by other- wise healthy youngsters whose hearing is impaired by a common childhood infection. otitis media Otitis media, a bacterial common bacterial infection of the infection of the middle middle ear that produces mild to ear, is the most frequently moderate hearing loss. diagnosed disease among infants and preschool children in Canada (Touchie, 2013). About 75 percent of children are infected at least once and recurrence is common (Vergison et al., 2010). Antibiotics can eliminate the bacteria that cause this disease but will © Bill Aron/PhotoEdit do nothing to reduce the buildup of fluid in the middle ear, which often persists without any symptoms of pain or discomfort. Unfortunately, this fluid may produce mild to moderate hearing loss that can last for months after an infection has been detected and treated (Halter et al., 2004; Very young infants are particularly responsive to the sound Vergison et al., 2010). of human voices. Otitis media strikes hardest between the ages of 6 months and 3 years. As a result, developmentalists feared that language) (Nittrouer & phonemes youngsters with recurring infections may have difficulty Burton, 2005). Older the basic units of sound that are understanding others’ speech, which could hamper their children with histories of used in a spoken language. language development and other cognitive and social skills chronic OM have that normally emerge early in childhood (Roberts, Rosenfeld, more difficulty when asked to recall a series of words, as & Zeisel, 2004; Vernon-Feagans, Hurley, Yont, Wamboldt, well as more difficulty comprehending syntactically complex & Kolak, 2007). sentences (Nittrouer & Burton, 2005). Children with recurring Research indicates that children who have had recurring infections show poorer academic performance early in ele- ear infections early in life do show delays in language devel- mentary school than peers whose bouts with the disease were opment. For example, Susan Rvachew and her colleagues at less prolonged (Friel-Patti & Finitzo, 1990; Teele et al., 1990). McGill University demonstrated that not only do infants with A longitudinal study conducted with over 1000 children in early-onset otitis media (OM) not produce speech-like babble New Zealand revealed that poor academic performance in at the expected age (Rvachew, Slawinski, Williams, & Green, reading as well as hyperactive and inattentive behaviour 1999), they have difficulties discriminating syllables (e.g., boo issues associated with chronic otitis media persist later into vs goo) (Polka & Rvachew, 2005). They also exhibit impaired childhood and adolescence (Bennett, Haggard, Silva, & Stewart, auditory attention skills (Asbjørnsen et al., 2005). In addition, 2001). The early returns clearly imply that young children with compared to those who have no history of chronic OM, very mild to moderate hearing loss are likely to be developmentally young children with histories of chronic OM perform more disadvantaged and that otitis media, a major contributor to poorly on tasks that involve syllable and phoneme awareness early hearing loss, needs to be detected early and treated (syllables are made up of consonant-vowel clusters, and aggressively (Jung et al., 2005). phonemes are basic units of sound that are used in a spoken harder to hear those particular passages than to hear other samples of their mother’s speech. Might these preferences reflect the experiences a baby had before birth, as he or she listened to his mother’s muffled voice through the uterine wall? Probably so, because researchers (DeCasper et al., 1994; Kisilevsky et al., 2003) have found that fetuses in their third trimester experience changes in their heart rate when responding to information provided by mothers. Specifically, DeCasper and Spence (1994) found changes between familiar and novel passages read by their mothers, and Barbara Kisilevsky and colleagues at Queen’s University (2003) found changes between passages read by their mother and a stranger. These studies provide a clear indication that the fetuses were learning sound patterns before birth. This special responsiveness to mother’s voice after birth may even be highly adaptive if it encourages a mother to talk to her infant and to provide the attention and affection that foster healthy social, emotional, and intellectual development. NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Chapter 7 | Early Cognitive Foundations: Sensation, Perception, and Learning 185 Clearly, in the healthy fetus, learning the mother’s voice occurs under naturalistic conditions with no environmental manipulation necessary. It is speculated that fetal rec- ognition of the mother’s voice is based on prosodic cues (pitch, juncture, stress, etc.), as has been suggested for infants (Floccia, Nazzi, & Bertoncini, 2000). If so, then the fetuses must have learned the prosodic information specific to their mother’s voice during repeated exposure. This indicates that, before birth, environmental sounds are available for shaping neural networks and laying the foundation for language acquisition. Fetal recognition of the mother’s voice also provides evidence that prenatal learning influences neonatal preferences. In particular, it supports the speculation that the pre- natal learning of the mother’s voice is responsible for the newborn’s preference for the maternal voice (DeCasper & Fifer, 1980) and face (Sai, 2005), compared to those of a female stranger. Fetal learning of the mother’s voice raises other questions about auditory informa- tion processing before birth. For example, does the fetus learn the father’s voice, which also would be expected to be experienced frequently? What about recognition of the native versus a foreign language? Understanding more about what sounds the fetus is learning and how this learning affects auditory development and behaviour is critical for a better understanding of brain development before birth. Reactions to Speech Babies not only attend closely to voices but also to speech. Using the high-amplitude sucking method, newborns have been shown to demonstrate a preference for speech that was modified to mimic speech they heard in utero instead of nonspeech sounds (Vouloumanos & Werker, 2007). By 3 months old, infants will turn their heads to hear non-native speech but not other nonspeech (e.g., human vocalizations) and water envi- ronmental sounds (e.g., boiling or dripping water; Shultz & Vouloumanos, 2010). By 4½ months, they will reliably turn their heads to hear their own name but not to hear other names, even when these other names share the same stress pattern as their own— such as “Abbey” versus “Johnny,” for example (Mandel, Jusczyk, & Pisoni, 1995). Babies this young probably do not know that the word for their name refers to them, but they are able to recognize such frequently heard words very early in life. At 5 months, if the speaker is loud enough, infants are able to detect their own names against a background of babbling voices. The volume of the spoken name must be around 10 decibels higher than the volume of the background voices. At about 1 year, infants turn in response to their own names when the names are only 5 decibels louder than background voices (Newman, 2005). Taste and Smell Infants are born with some very definite taste preferences. For example, they apparently come equipped with something of a sweet tooth, because both full-term and premature babies suck faster and longer for sweet liquids than for bitter, sour, salty, or neutral (water) solutions (Crook, 1978; Smith & Blass, 1996). Different tastes also elicit different facial expressions from newborns, as young as 2 hours old (Oster, 2005). Sweets reduce crying and produce smiles and smacking of the lips, whereas sour substances cause infants to wrinkle their noses and purse their lips. Bitter solutions often elicit expressions of disgust—a down-turning of the corners of the mouth, tongue protrusions, and even spit- ting (Blass & Ciaramitaro, 1994; Ganchrow, Steiner, & Daher, 1983). Furthermore, these facial expressions become more pronounced as solutions become sweeter, more sour, or more bitter, suggesting that newborns can discriminate different concentrations of a particular taste. Newborns are also capable of detecting a variety of odours, and they react vigorously by turning away and displaying expressions of disgust in response to unpleasant smells ‫ﻣﺛل اﻟﺧل واﻷﻣوﻧﯾﺎ‬ such as vinegar, ammonia, or rotten eggs (Rieser, Yonas, & Wilkner, 1976; Steiner, 1979). ‫واﻟﺑﯾض اﻟﻔﺎﺳد‬ NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it. 186 Part Three | Language, Learning, and Cognitive Development In the first 4 days after birth, babies already prefer the odour of milk to that of amniotic fluid (in which they have been living for 9 months; Marlier, Schall, & Soussignan, 1998). And a 1- to 2-week-old breastfed infant can already recognize her or his mother (and discriminate her from other women) by the smell of her breasts and underarms (Cernoch & Porter, 1985; Porter, Makin, Davis, & Christensen, 1992). Like it or not, each of us has a unique “olfactory signature”—a characteristic odour that babies can use as an early means of identifying their closest companions. To demonstrate this discrimination of mother by smell, Macfarlane (1977) asked nursing mothers to wear breast pads in their bras between nursings (such pads absorb milk and odours from the breast that may be emitted between nursings). Next, 2-day-old or 6-day-old nursing infants were observed lying down with a breast pad from their own mother on one side of their heads and the breast pad of another nursing mother on the other side of their heads. Macfarlane found that the 2-day-old infants showed no differ- ence in which breast pad they turned to. In contrast, the 6-day-old infants consistently turned to the side facing their mother’s breast pad. This demonstrated that the infants had learned their mother’s unique smell in their first week of life and had also developed a preference for her smell over the smells of other nursing women. WHAT DO YOU THINK? ? Touch, Temperature, and Pain Based on what you now know Receptors in the skin are sensitive to touch, temperature, and pain. We learned in Chapter about a newborn’s sensory capa- 5 that newborn infants reliably display a variety of reflexes if they are touched in the bilities, prepare a brief descrip- appropriate areas. Even while sleeping, neonates habituate to stroking at one locale but tion of what a newborn might respond again if the tactile stimulation shifts to a new spot—from the ear to the chin, for sense as he or she gazes at his or example (Kisilevsky & Muir, 1984). her attentive mother and other parent. Can you think of any Sensitivity to touch clearly enhances infants’ responsiveness to their environments. reason that the baby might be Premature infants show better developmental progress when they are periodically quicker to orient to one parent stroked and massaged in their isolettes. Touch and close contact promote developmental than the other? If so, which progress in all infants, not just premature babies. Touch lowers stress levels, calms, and parent, and why? promotes neural activity (Diamond & Amso, 2008; Field et al., 2004). The therapeutic effect of touch is also due, in part, to the fact that gentle stroking and massaging arouses inattentive infants and calms agitated ones, often causing them to smile at and become more involved with their companions (Field et al., 1986; Stack & Muir, 1992). Later in the first year, babies begin to use their sense of touch to explore objects—first with their lips and mouths, and later with their hands. So touch is a primary means by which infants acquire knowledge about their environment, which contributes to their early cognitive development (Piaget, 1960). Newborns are also quite sensitive to warmth, cold, and changes in temperature. They refuse to suck if the milk in their bottles is too hot, and they try to maintain their body heat by becoming more active should the temperature of a room suddenly drop (Pratt, 1954). Do babies experience much pain? Apparently so, for even 1-day-old infants cry loudly when pricked by a needle for a blood test. In fact, very young infants show greater distress upon receiving an inoculation than 5- to 11-month-olds do (Axia, Bonichini, & Benini, 1999). However, such pain experienced by newborns could be reduced drastically if they are held by their mother, providing them with skin-to-skin contact (Gray, Watt, & Blass, 2000). In fact, infants who had skin-to-skin contact with their mothers cried 82 percent less and grimaced 65 percent less than those who were in a crib during a blood test. Besides skin-to- skin contact, pain experience (once again, measured by crying and grimacing) caused by a needle prick can also be reduced simply by keeping newborns in a warm environment (Gray, Lang, & Porges, 2012). Keeping newborns warm is a more effective analgesia than a sugar solution and pacifier during vaccination (Gray et al., 2012). Male babies are highly stressed by circumcision, an elective operation that is usually done without anesthesia because giving pain-killing drugs to infants is itself very risky (Hill, 1997). While the surgery is in progress, infants emit high-pitched wails that are NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Chapter 7 | Early Cognitive Foundations: Sensation, Perception, and Learning 187 similar to the cries of premature babies or those who are brain-damaged (Porter, Porges, & Marshall, 1988). Moreover, plasma cortisol, a physiological indicator of stress, is sig- nificantly higher just after a circumcision than just before the surgery (Gunnar, Malone, Vance, & Fisch, 1985). Findings such as these, however, challenge the medical wisdom of treating infants as if they are insensitive to pain. Researchers have found that babies treated with a mild topical anesthetic before circumcision—though even topical anesthetics can pose risks (Engberg et al., 1985)—and given a sugary solution to suck afterward are less stressed by the operation and are able to sleep more peacefully (Hill, 1997). In 1996, the Canadian Paediatric Society re-evaluated its position on circumcision and suggested that the procedure is largely unnecessary, and currently most Canadian provincial health insurance plans no longer pay for this procedure. Vision ‫ﺷﻌور ﻻ ﻏﻧﻰ ﻋﻧﮫ‬ Although most of us tend to think of vision as our most indispensable sense, it may be the least mature of the newborn’s sensory capabilities. Changes in brightness will elicit a subcortical pupillary reflex, which indicates that the neonate is sensitive to light (Pratt, 1954). Babies can also detect movement in the visual field and are likely to track a visual stimulus with their eyes, as long as the target moves slowly (Banks & Salapatek, 1983). Newborn infants are more likely to track faces (or facelike stimuli) than other pat- terns ( Johnson, Dziurawiec, Ellis, & Morton, 1991), although this preference for faces disappears within 1 or 2 months. Demonstrating this preference, Johnson and his col- leagues prepared three head-shaped cutouts with different drawings on them: one was a human face, one a scrambled version of face parts, and one was blank. They moved these cutouts in the visual field of infants just minutes old to 5 weeks old. They found that the infants were more likely to follow (both with their eyes and their heads) the movement of the cutout with the human face than either of the other two stimuli. This demon- strated that infants just minutes old could track a visual stimulus with their eyes and heads and that they showed a preference for the human face. How do newborns recog- nize faces? Despite their poor vision, they use both outer facial features (such as hair and ears) as well as inner facial features (such as eyes, nose, and mouth), although outer facial features are preferred over inner ones (Turati, Cassia, Simion, & Leo, 2006). Given their ability in facial recognition, do they have a visual preference for their mother’s face? Steve McAlister/Getty Images Steve McAlister/Getty Images (a) Newborn’s view (b) Adult’s view The newborn’s limited powers of accommodation and poor visual acuity make the mother’s face look fuzzy (photo A) rather than clear (photo B), even when viewed from close up. (Try it yourself by moving the photos to within 15 to 20 cm of your face.) NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it. 188 Part Three | Language, Learning, and Cognitive Development In fact, studies show that they do. Newborns who are only a few hours old prefer their mother’s face over that of a female stranger (Bushnell, 2001; Bushnell, Sai, & Mullin, 1989; Field, Cohen, Garcia, & Greenberg, 1984; Pascalis, de Schonen, Morton, Deruelle, & Fabre-Grenet, 1995). Why do babies display this preference? One possibility is that it represents an adaptive remnant of our evolutionary history—a reflex, controlled by sub- cortical areas of the brain, that serves to orient babies to their caregivers and promote social interactions ( Johnson et al., 1991). Using the habituation method, Russell Adams and Mary Courage of Memorial University of Newfoundland (1998) have found that neonates see the world in colour, but they have trouble discriminating blues, greens, and yellows from whites (Adams & Courage, 1998). However, rapid development of the visual brain centres and sensory pathways allows their colour vision to improve quickly. By 2 to 3 months of age, babies can discriminate all the basic colours (Bornstein, 2015; Brown, 1990; Matlin & Foley, 1997), and by 4 months they are grouping colours of slightly different shades into the same basic categories—the reds, greens, blues, and yellows—that adults do (Franklin, 2015; Bornstein, Kessen, & Weiskopf, 1976). Despite these impressive capabilities, very young infants do not resolve fine detail visual acuity very well (Kellman & Arteberry, 2007). Neonates are born “legally blind,” with visual person’s ability to see small objects acuity around 20/400, which means they can see at 6 m what an adult with excellent and fine detail. vision sees at 120 m. What’s more, objects at any distance look rather blurry to a very young infant, who has trouble accommodating—that is, changing the shape of the lens of the eye to bring visual stimuli into focus. Given these limitations, it is perhaps not sur- prising that many patterns and forms are difficult for a very young infant to detect; visual contrast infants simply require sharper visual contrasts to “see” them than adults do (Kellman & amount of light/dark transition in a Arteberry, 2007). However, acuity improves very rapidly over the first few months visual stimulus. (Courage & Adams, 1996). By age 6 months, babies’ visual acuity is about 20/100 (Marg, Freeman, Peltzman, & Goldstein, 1976; Norcia & Tyler, 1985), and by age 12 months they see about as well as adults do (Kellman & Arteberry, 2007). In sum, the young infant’s visual system is not operating at peak efficiency, but it certainly is working. Even newborns can sense movement, colours, changes in bright- ness, and a variety of visual patterns—as long as these patterned stimuli are not too finely detailed and have a sufficient amount of light/dark contrast. Visual functions evident in newborns are largely experience-independent. As infants explore the world with their eyes, experience-dependent mechanisms—such as synaptic reinforcement—begin to contribute to the development of visual acuity. Thus, both experience-independent and experience-dependent mechanisms promote the development of the infant’s visual sys- tems (Fox, Levitt, & Nelson, 2010; Johnson, 2001). Overall, each of the major senses is functioning at birth (see Table 7.1 for a review), so even neonates are well prepared to see their environments. But do they interpret this input? Can they perceive? TAbLE 7.1 The Newborn’s Sensory Capabilities Sense Newborn’s Capabilities Vision Least well-developed sense; accommodation and visual acuity limited; is sensitive to brightness; can discriminate some colours; tracks moving targets. Hearing Turns in direction of sounds; less sensitive to soft sounds than an adult would be but can discriminate sounds that differ in such dimensions as loudness, direction, and frequency; particularly responsive to speech; recognizes mother’s voice. Taste Prefers sweet solutions; can discriminate sweet, salty, sour, and bitter tastes. Smell Detects a variety of odours; turns away from unpleasant ones; if breastfed, can identify mother by the odour of her breast and underarm area. Touch Responsive to touch, temperature change, and pain. NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Chapter 7 | Early Cognitive Foundations: Sensation, Perception, and Learning 189 Visual Perception in Infancy Although newborn infants see well enough to detect and even discriminate some pat- terns, we might wonder what they “see” when looking at these stimuli. If we show them a , do they see a square, or must they learn to construct a square from an assortment of lines and angles? When do they interpret faces as meaningful social stimuli or begin to distinguish the faces of close companions from those of strangers? Can neonates per- ceive depth? Do they think receding objects shrink, or do they know that these objects remain the same size and only look smaller when moved away? These are precisely the kinds of questions that have motivated curious investigators to develop research methods to determine what infants see. Perception of Patterns and Forms Recall Robert Fantz’s observations of infants in his looking chamber. Babies only 2 days old could easily discriminate visual patterns. In fact, of all the targets that Fantz pre- sented, the most preferred stimulus was a face! Does this imply that newborns already interpret faces as a meaningful pattern? Early Pattern Perception (0 to 2 Months) Apparently not. When Fantz (1961) presented young infants with a face, a stimulus consisting of scrambled facial features, and a simpler stimulus that contained the same amount of light and dark shading as the facelike and scrambled face drawings, the infants were just as interested in the scrambled face as the normal one (see Figure 7.7). Later research revealed that very young infants prefer to look at high-contrast patterns with many sharp boundaries between light and dark areas, and at moder- ately complex patterns that have curvilinear features (Kellman & Arteberry, 2007). So faces and scrambled faces may have been equally interesting to Fantz’s young subjects (a) (b) (c) because these targets had the same amount of contrast, 60 curvature, and complexity. By analyzing the characteristics of stimuli that very young infants will or will not look at, we can estimate what they see. Seconds of fixation in 2-minute test 50 A Figure 7.7, for example, indicates that babies less than B 2 months old see only a dark blob when looking at a highly 40 complex checkerboard, probably because their immature eyes don’t accommodate well enough to resolve the fine detail. 30 However, the infant sees a definite pattern when gazing at the moderately complex checkerboard (banks & Salapatek, 1983). 20 Martin Banks and his associates (see also Banks & Ginsurg, 1985) have summarized the looking preferences of very young C infants quite succinctly: babies prefer to look at whatever they 10 see well, and the things they see best are moderately complex, high-contrast targets, particularly those that capture their 4 days 1 month 2 months attention by moving. Age of infants Clearly, very young infants can detect and discriminate different patterns. But can they perceive forms? If shown a Figure 7.7 Fantz’s test of young infants’ pattern preferences. Infants preferred to look at complex stimuli rather than at a simpler triangle, do they see the ∇ that we do? Or, rather, do they black-and-white oval (c). However, the infants did not prefer the detect only pieces of lines and maybe an angle (such as /)? facelike figure (a) to the scrambled face (b). Although the answers to these questions are by no means Source: Adapted from “The Origin of Form Perception,” by R.l. Fantz, May established, most researchers believe that 1- to 2-month-old 1961, Scientific American, 204, p. 72 (top). Copyright © 1961 by Scientific infants detect few if any forms because they see so poorly American, Inc. and they scan visual stimuli in a very limited way NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it. 190 Part Three | Language, Learning, and Cognitive Development What we see (see Figures 7.8 and 7.9) (Haith, 2004). So unless the form is very small, they are unlikely to see all of it, much less put all Moderately complex Highly complex 66 1616 this information together to perceive a unified whole. Later Form Perception (2 Months to 1 Year) Between 2 and 12 months of age, the infant’s visual system is rapidly maturing. He or she now sees better and is capable of making increasingly complex visual discriminations, eventually being able to discriminate temporal movement sequencing (Kirkham, Slemmer, Richardson, & Johnson, 2007). The infant is also organizing what she or he sees to perceive visual forms and sets of separate forms (Cordes & Brannon, 2008). By 5 months old, the infant is able to form an What the young infant sees accurate image of an object in three-dimensional form after seeing a series of two-dimensional images of the object from multiple per- spectives. He or she is able to recognize the object even when it was inverted upside-down (Mash, Arteberry, & Bornstein, 2007). The most basic task in perceiving a form is to discriminate that object from its surrounding context (i.e., other objects and the general background). How do you suppose an infant eventu- ally recognizes that a bottle of milk in front of a centrepiece on the dining room table is not just a part of the centrepiece? What information does the infant use to perceive forms, and when does Figure 7.8 What patterns look like to the young eye. By the time these two checkerboards are processed by eyes with poor he or she begin to do so? vision, only the checkerboard on the left may have any pattern Philip Kellman and Elizabeth Spelke (1983; Kellman, Spelke, & left to it. Poor vision in early infancy helps explain a preference Short, 1986) were among the first to explore these issues. Infants for moderately complex rather than highly complex stimuli. were presented with a display consisting of a rod partially hidden by Source: Adapted from “Infant Visual Perception,” by M.S. Banks, in a block in front of it (see Figure 7.10, A and B). Would they perceive collaboration with P. Salapatek, 1983, in Handbook of Child Psychology, the rod as a whole object, even though part of it was not visible, or Vol. 2: Infancy and Developmental Psychobiology, by M.M. Haith & would they act as though they had seen two short and separate rods? J.J. Campos (Eds.). Copyright (c) 1983 by John Wiley & Sons. Adapted To find out, 4-month-olds were first presented with either dis- by permission of John Wiley & Sons, Inc. play A (a stationary hidden rod) or display B (a moving hidden rod) and allowed to look at it until they habituated and were no longer interested. Then infants were shown displays C (a whole rod) and D (two rod segments) and their looking preferences were recorded. Infants who had (a) (b) habituated to the stationary hidden rod Finish (display A) showed no clear preference for Start display C or D in the later test. They were apparently not able to use available cues, such as the two identical rod tips oriented along the same line, to perceive a whole rod Finish when part of the rod had been hidden. By contrast, infants did apparently perceive the moving rod (display B) as “whole,” for after Start habituating to this stimulus, they much pre- ferred to look at the two short rods (display D) than at a whole rod (display C, which they 1-month-old 2-month-old 1-month-old 2-month-old now treated as familiar). It seems that these latter infants inferred the rod’s wholeness Figure 7.9 By photographing eye movements, researchers can determine what babies are looking at when scanning a visual stimulus. Although very young infants rarely scan an from its synchronized movement—the fact entire form, 1-month-olds scan much less thoroughly than 2-month-olds do, that its parts moved in the same direction at concentrating most on specific outer edges or boundaries and least on internal features. the same time. So infants rely heavily on Source: Adapted from “Pattern Perception in Infancy,” by P. Salapatek, 1975, in Infant Perception: From kinetic motion cues to identify distinct forms Sensation to Cognition, by L.B. Cohen & P. Salapatek (Eds.). Copyright © 1975 by Academic Press, ( Johnson & Mason, 2002; Kellman & Inc. Adapted by permission. Arteberry, 2007). NEL Copyright 2020 Nelson Education Ltd. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Nelson Education reserves the right to remove additional content at any time if subsequent rights restrictions require it.  Chapter 7 | Early Cognitive Foundations: Sensation, Perception, and Learning 191 Habituation stimuli Test stimuli (a) (b) (c) (d) Figure 7.10 Perceiving objects as wholes. An infant is habituated to a rod partially hidden by the block in front of it. The rod is either stationary (a) or moving (b). When tested afterward, does the infant treat the whole rod (c) as “old hat”? We certainly would, for we could readily interpret cues that tell us that there is one long rod behind the block and would therefore regard the whole rod as familiar. But if the infant shows more interest in the whole rod (c) than in the two rod segments (d), he or she has apparently not been able to use available cues to perceive the whole rod. Source: Adapted from “Perception of Partly Occluded Objects in Infancy,” by P.J. Kellman & E.S. Spelke, 1983, Cognitive Psychology, 15, pp. 483–524. Copyright © 1983 by Academic Press, Inc. Interestingly, this impressive ability to use object movement to perceive form is apparently not present at birth (Slater et al., 1990) but has developed by 2 months of age ( Johnson & Aslin, 1995). By 3 to 4 months, infants can even perceive form in some sta- tionary scenes that capture their attention. Look carefully at Figure 7.11. Do you see a square in this display? So do 3- to 4-month-olds (Ghim, 1990)—a remarkable achievement indeed, for the boundary of this “square” is a subjective contour that must be constructed mentally rather than simply detected by the visual system. Further strides in form perception occur later in the first year as infants come to detect more and more about structural configurations from the barest of cues (Craton, 1996). At about 8 months, infants no longer need kinetic cues to perceive a partially obscured rod as whole ( Johnson & Richard, 2000; Kavšek, 2004). By 9 months, infants exposed to the moving point-light displays shown in Figure 7.12 pay much more attention to display A than to displays B and C, as if they were interpreting this stimulus as a representation of (a) (b) (c)