Sensorimotor Intelligence

As you remember from Chapter 2, Jean Piaget was a Swiss scientist who earned his doctorate in 1918, when most scientists thought infants ate, cried, and slept but did not yet learn. When Piaget became a father, he used his scientific observation skills with his own babies, and, contrary to conventional wisdom (including that of Uncle Henry), he realized that infants are active learners, adapting to experience. His theories and observations have earned Piaget the admiration of developmentalists ever since. [Lifespan Link: See Chapter 2.]

Piaget called cognition in the first two years sensorimotor intelligence. The reflexes, senses, and motor skills described in Chapters 4 and 5 are used by infants to develop their minds, adapting to experience. Sensorimotor intelligence is subdivided into six stages (see Table 6.1).

Stages One and Two: Primary Circular Reactions

Piaget described the interplay of sensation, perception, and cognition as circular reactions, emphasizing that, as in a circle, there is no beginning and no end because each experience leads to the next, which loops back (see Figure 6.1). The first two stages of sensorimotor intelligence are primary circular reactions, involving the infant’s body.

Never Ending Circular reactions keep going because each action produces pleasure that encourages more action.

Stage one, called the stage of reflexes, lasts only a month. It includes senses as well as motor reflexes, the foundations of infant thought. Soon reflexes become deliberate; sensation leads to perception, perception leads to cognition, and then cognition leads back to sensation.

Stage two, first acquired adaptations (also called stage of first habits), begins because reflexes adjust to whatever responses they elicit. Adaptation is cognitive; it includes both assimilation and accommodation. [Lifespan Link: See Chapter 2.] Infants adapt their reflexes as their responses teach them about what the body does and how each action feels.

Here is one example. In a powerful reflex, full-term newborns suck anything that touches their lips. By about 1 month, infants adapt this reflex to bottles or breasts, pacifiers or fingers, each requiring specific types of tongue pushing. This adaptation is a sign that infants have begun to interpret their perceptions; as they accommodate to pacifiers, they are “thinking.”

During stage two, which Piaget pegged from about 1 to 4 months of age, additional adaptation of the sucking reflex begins. Infant cognition leads babies to suck in some ways for hunger, in other ways for comfort—and not to suck fuzzy blankets or large balls. Once adaptation occurs, it sticks.

For instance, breast-fed babies may reject milk from the nipple of a bottle if they have never experienced it early on. If parents of a 4-month-old thumb-sucker then decide that a pacifier would be better, it may be too late. Their baby may refuse to readapt, a refusal that is evident when the baby spits out the pacifier and finds the thumb instead. Piaget believed that people of all ages tend to be stuck in their ways for cognitive reasons; early adaptation is one example.

Stages Three and Four: Secondary Circular Reactions

In stages three and four, development advances from primary to secondary circular reactions. Those reactions extend beyond the infant’s body; they are a circular reaction between the baby and something else.

During stage three (4 to 8 months), infants attempt to produce exciting experiences, making interesting events last. Realizing that rattles make noise, for example, they wave their arms and laugh whenever someone puts a rattle in their hand. The sight of something delightful—a favorite book, a smiling parent—can trigger active efforts for interaction.

Next comes stage four (8 months to 1 year), new adaptation and anticipation (also called the means to the end). Babies may ask for help (fussing, pointing, gesturing) to accomplish what they want. Thinking is more innovative because adaptation is more complex. For instance, instead of always smiling at Daddy, an infant might first assess his mood. Stage-three babies know how to continue an experience; stage-four babies initiate and anticipate.

Time for Adaptation Sucking is a reflex at first, but adaptation begins as soon as an infant differentiates a pacifier from her mother’s breast or realizes that her hand has grown too big to fit into her mouth. This infant’s expression of concentration suggests that she is about to make that adaptation and suck just her thumb from now on.

FSTOP/PUNCHSTOCK

The impressive attribute of stage four is that babies work hard to achieve their goals. A 10-month-old girl might crawl over to her mother, bringing a bar of soap as a signal to start her bath, and then remove her clothes to make her wishes crystal clear—finally squealing with delight when the bath water is turned on. Similarly, if a 10-month-old boy sees his father putting on his coat to leave, he might drag over his own jacket to signal that he wants to go along.

At that age, babies indicate that they are hungry—and keep their mouths firmly shut if the food on the spoon is something they do not like. If the caregivers have been using sign language, among the first signs learned by 10-month-olds are “eat” and “more.” These cognitive advances benefit from new motor skills (e.g., crawling, grabbing, hand gestures), which result from brain maturation—dynamic systems again.

Piaget thought that, at about 8 months, babies first understand the concept of object permanence—the realization that objects or people continue to exist when they are no longer in sight. As Piaget discovered, not until about 8 months do infants search for toys that have fallen from the crib, rolled under a couch, or disappeared under a blanket. Blind babies also acquire object permanence toward the end of their first year, reaching for an object that they hear nearby (Fazzi et al., 2011).

Family Fun Peek-a-boo makes all three happy, each for cognitive reasons. The 9-month-old is discovering object permanence, his sister (at the concrete operational stage) enjoys making brother laugh, and their mother understands more abstract ideas—such as family bonding.

BAMBU PRODUCTIONS/GETTY IMAGES

As they grow older, toddlers become better at seeking hidden objects, which Piaget again considered symptomatic of sensorimotor advances. Piaget developed a basic experiment to measure object permanence: An adult shows an infant an interesting toy, covers it with a lightweight cloth, and observes the response. The results:

• Infants younger than 8 months do not search for the object (by removing the cloth).
• At about 8 months, infants search immediately (removing the cloth) after the object is covered but not if they have to wait a few seconds.
• At 18 months, they search quite well, but not if they have seen the object put first in one place and then moved to another. They search in the first place, a mistake called A-not-B.
• By 2 years, children fully understand object permanence, progressing through several stages of ever-advanced cognition (Piaget, 1954).

This research provides many practical suggestions. If young infants fuss because they see something they cannot have (keys, a cigarette, candy), put that coveted object out of sight. Fussing stops.

By contrast, for toddlers, hiding a forbidden object is not enough. It must be securely locked up or discarded, lest the child later retrieve it, climbing onto the kitchen counter or under the bathroom sink to do so. Since object permanence develops gradually, games such as peek-a-boo and hide-and-seek are too advanced in the first months, but they are fun once object permanence is newly understood. As comprehension of hidden objects matures, peek-a-boo becomes boring, but hide-and-seek becomes more elaborate (longer waiting, more imaginative hiding).

Piaget believed that failure to search before 8 months of age meant that infants had no concept of object permanence—that “out of sight” literally means “out of mind.” That belief has been questioned. As one researcher points out, “Amid his acute observation and brilliant theorizing, Piaget…mistook infants’ motor incompetence for conceptual incompetence” (Mandler, 2004, p. 17). A series of clever experiments in which objects seemed to disappear behind a screen while researchers traced babies’ eye movements and brain activity revealed that long before 8 months infants are surprised if an object vanishes (Baillargeon & DeVos, 1991; Spelke, 1993).

Further research on object permanence continues to raise questions and produce surprises. For instance, many other creatures (cats, monkeys, dogs, birds) develop object permanence at younger ages than Piaget found. Does this reflect slower development of the human brain or simply slower maturation of motor skills (Bruce & Muhammad, 2009)?

Stages Five and Six: Tertiary Circular Reactions

In their second year, infants start experimenting in thought and deed—or, rather, in the opposite sequence, deed and thought. They act first (stage five) and think later (stage six).

Tertiary circular reactions begin when 1-year-olds take independent actions to discover the properties of other people, animals, and things. Infants no longer respond only to their own bodies (primary reactions) or to other people or objects (secondary reactions). Their cognition is more like a spiral than a closed circle, increasingly creative with each discovery.

Piaget’s stage five (ages 12 to 18 months), new means through active experimentation, builds on the accomplishments of stage four. Now goal-directed and purposeful activities become more expansive.

Toddlers delight in squeezing all the toothpaste out of the tube, taking apart an iPod, or uncovering an anthill, activities they have never seen an adult do. Piaget referred to the stage-five toddler as a “little scientist” who “experiments in order to see.” Their scientific method is trial and error. Their devotion to discovery is familiar to every adult scientist—and to every parent.

Exploration at 15 Months One of the best ways to investigate food is to squish it in your hands, observe changes in color and texture, and listen for sounds. Taste and smell are primary senses for adults when eating, but it looks as if Jonathan has already had his fill of those. ARIEL SKELLEY/AGE FOTOSTOCK

Push Another Button Little scientists “experiment in order to see” as this 14-month-old does. Many parents realize, to their distress, that their infant has deleted a crucial file, or called a distant relative on a cell phone, because the toddler wants to see what happens. TOOGA PRODUCTIONS, INC./GETTY IMAGES.

Finally, in the sixth stage (ages 18 to 24 months), toddlers use mental combinations, intellectual experimentation via imagination that can supersede the active experimentation of stage five. Thankfully, the stage-six sequence may begin with thought (especially if the toddler remembers that something was forbidden) and then move on to action. Of course, the urge to explore may overtake memories of prohibition: Things that are truly dangerous (poisons, swimming pools, open windows) need to be locked and gated, not simply forbidden.

Another major cognitive accomplishment at the sixth stage is that toddlers can pretend. For instance, they know that a doll is not a real baby, but they can belt it into a stroller and take it for a walk. At 22 months my grandson gave me imaginary “shoe ice cream” and laughed when I pretended to eat it.

Because they combine ideas, stage-six toddlers think about consequences, hesitating a moment before yanking the cat’s tail or dropping a raw egg on the floor. Of course, their strong drive to discover may overwhelm reflection; they do not always choose wisely.

Piaget describes another stage-six intellectual accomplishment involving both thinking and memory. Deferred imitation occurs when infants copy behavior they noticed hours or even days earlier (Piaget, 1945/1962). Piaget described his daughter, Jacqueline, who observed another child

Piaget and Modern Research

As detailed by hundreds of developmentalists, many infants reach the stages of sensorimotor intelligence earlier than Piaget predicted (Oakes et al., 2011). Not only do 5-month-olds show surprise when objects seem to disappear (evidence of object permanence before 8 months) but babies younger than 1 year pretend and defer imitation (both stage-six abilities, according to Piaget) (Bauer, 2006; Fagard & Lockman, 2010; Hayne & Simcock, 2009; Meltzoff & Moore, 1999). How could a gifted scientist be so wrong? There are at least three reasons.

First, Piaget’s original insights were based on his own infants. Direct observation of three children is a start, and Piaget was an extraordinarily meticulous and creative observer, but no contemporary researcher would stop there. Given the immaturity and variability of babies, dozens of infants must be studied. For instance, as evidence for early object permanence, Baillargeon (2000) listed 30 studies involving more than a thousand infants younger than 6 months old.

Second, infants are not easy to study; there are problems with “fidelity and credibility” (Bornstein et al., 2005, p. 287). To overcome these problems, modern researchers use innovative statistics, research designs, sample sizes, and strategies that were not available to Piaget—often finding that object permanence, deferred imitation, and other sensorimotor accomplishments occur earlier, and with more variation, than Piaget had assumed (Hartmann & Pelzel, 2005; Kolling et al., 2009). For instance, if an infant looks a few milliseconds longer when an object seems to have vanished, is that evidence of object permanence? Many researchers believe the answer is yes—but only advanced cameras, programmed by computers, can measure it.

One particular research strategy has been a boon to scientists, confirming the powerful curiosity of very young babies. That research method is called habituation (from the word habit). Habituation refers to getting accustomed to an experience after repeated exposure, as when the school cafeteria serves macaroni day after day or when infants repeatedly encounter the same sound, sight, toy, or so on. Evidence of habituation is loss of interest (or, for macaroni, loss of appetite).

Using habituation as a research strategy with infants involves repeating one stimulus until babies lose interest and then presenting another, slightly different stimulus (a new sound, sight, or other sensation). Babies indicate that they detect a difference between the two stimuli with a longer or more focused gaze; a faster or slower heart rate; more or less muscle tension around the lips; a change in the rate, rhythm, or pressure of suction on a nipple. Such subtle indicators are recorded by technology that was unavailable to Piaget (such as eye-gaze cameras and heart monitors).

By inducing habituation and then presenting a new stimulus, scientists have learned that even 1-month-olds can detect the difference between a pah sound and a bah sound, between a circle with two dots inside it and a circle without any dots, and much more. Babies younger than 6 months perceive far more than Piaget imagined.

Third, several ways of measuring brain activity now allow scientists to record infant cognition long before any observable evidence is found (see Table 6.2) (Johnson, 2010). In fMRI (functional magnetic resonance imaging), a burst of electrical activity measured by blood flow within the brain is recorded, indicating that neurons are firing. This leads researchers to conclude that a particular stimulus has been noticed and processed. Moreover, scientists now know exactly which parts of the brain signify what sensations or thoughts, so electrical activity in the face area, for instance, means that the infants is processing a face.

Table : TABLE 6.2Some Techniques Used by Neuroscientists to Understand Brain Function

SPL/SCIENCE SOURCE (Top left)LANGOLIS SOCIAL DEVELOPMENT LAB (Top right)STEGERPHOTO/GETTY IMAGES (Bottom left)HANK MORGAN/SCIENCE SOURCE (Bottom right)

As time goes on, milliseconds of gaze, or blood flow in the brain, indicate that habitation has occurred. Based on advanced methods, scientists are convinced that infants have memories, goals, deferred imitation, and even mental combinations well in advance of Piaget’s stages (Bauer et al., 2010; Morasch & Bell, 2009).

Brain imagery of normal children is not only difficult and expensive, with interpretation sometimes controversial, but any scans of the head raise questions about long-term effects (Schenkman, 2011). Brain scans may provide crucial information if an infant is ill or injured, but many parents refuse to allow such measures with healthy infants. Such caution is understandable, even admirable, but it slows down neurological confirmation of infant cognition.

However, brain scans of non-human primates has revealed much about the human brain. That includes the discovery of mirror neurons. About two decades ago, scientists noticed that when a one monkey saw another reach for a banana, the same brain areas were activated (lit up in brain scans) in both monkeys. Those brain areas in the F5 area of the observing macaque’s premotor cortex were dubbed mirror neurons, because they reflected what was observed. Using increasingly advanced technology, neuroscientists have now found mirror neurons in several parts of the adult human brain (Keysers & Gazzola, 2010).

Many scientists have suggested that mirror neurons lead to exciting implications for infant cognition. Perhaps avid watching and listening enable babies to understand objects, language, and other people learn long before Piaget realized (Diamond & Amso, 2008; Rossi et al., 2011; Virji-Babul et al., 2012). A baby’s learning by observation may actually involved brain activity that mirrors what was seen and heard, so that as soon as physiological maturation makes it possible, the baby knows exactly what to do. He or she has already done it many times before—in the brain.