Cognition and Memory in Infants and Toddlers

Learning Objectives

By the end of this section, you will be able to:

• Identify milestones in cognitive development in infants and toddlers
• Describe the different methods for studying infant cognition
• Describe the types of memory and what is known about memory development in infancy
• Compare the major theories of cognitive development in infants and toddlers
• Describe variations in cognitive development in terms of environmental factors

Dante is the fourth child in his family and is now fifteen months old. As his grandfather begins to prepare dinner, he settles Dante on the floor where he can see him and gives him a wooden spoon, some teaspoons, and some pots and pans. Dante immediately begins to bang on the pans with the wooden spoon and then does the same with the teaspoons. He also takes the teaspoons and drops them into the smaller pot and then dumps them back out again. He repeats this process several times. Dante’s grandpa may not love the noise, but he loves knowing that his grandson is actively learning. He understands that toddlers need to explore their world using their senses and their motor skills, and that even everyday objects can be entertaining for young children.

In this section, you’ll learn the main theories of cognitive development. First is Piaget’s groundbreaking work, which continues to influence the fields of child development and education. Then you’ll consider current methods used to study infant and toddler cognition and an information processing model explaining the units and capacity of our attention and memory. Finally, you’ll see how cultural and social experiences can influence our learning, and you’ll account for individual differences in cognitive development.

Stage Theory of Cognitive Development

Jean Piaget (1896–1980) was an influential cognitive psychologist who originally trained as a biologist and philosopher. He spent more than five decades studying cognitive development and is most famous for his research and theory on the cognitive development of children. You’ll consider some key principles of the first stage of his theory in this section, as well as critiques of his work.

Background of Piaget’s Work

In Paris in the 1920s, Piaget noticed qualitative differences in the way children of different ages, including his own three, responded to questions and explained the world (Lascarides & Hinitz, 2011). He then used his detailed notes and observations to create a stage theory of cognitive development (Table 1.2).

Piaget’s theory is an example of discontinuous development, which you may recall from 1.2 Themes of Development is change that occurs in sudden shifts or as qualitative and dramatic changes in skills or behaviors. In other words, cognitive development happens in stages, in the same way a caterpillar changes into a chrysalis and then a butterfly.

Piaget theorized that we are working to make sense of the world, holding our knowledge in balance or cognitive equilibrium (Piaget, 1952, 1954). As we encounter information, we create schemas in which to catalog it. A schema is a mental framework that helps us organize and interpret information we receive from our environment. For example, you might have a schema for a bird: It has feathers, a beak, and wings; it flies; it lays eggs in a nest. You might even include a pet parakeet you had as an example.

Children develop and adjust schemas when they interact with their physical and social environments, experimenting and applying trial and error. Piaget explained these adjustments as the cognitive processes of assimilation and accommodation. Assimilation occurs when the information from your environment fits what you already know. Accommodation happens when you need to make changes to your knowledge because something doesn’t fit your existing schema. For example, a child might see a parrot and realize it is a bird with a beak and wings that flies (assimilation), but the child will need to accommodate when seeing a penguin, which is flightless, or a flamingo, which has a different body shape (Figure 3.16).

Figure 3.16 Assimilation fits new information into existing schemas, while accommodation rearranges, redefines, or creates schemas to make space for new information. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Both assimilation and accommodation occur throughout life as we adapt to our environments. Piaget theorized that the organization and coordination of schemas can lead to cognitive changes. When we go through major cognitive changes, we develop a new way of thinking and may even enter a new cognitive development stage.

Stage 1: Sensorimotor Development

Although Piaget’s theory is based not on age but on skills and ways of thinking, infants and toddlers are in stage 1. This sensorimotor development stage focuses primarily on children’s early experiences of the world, when they are actively learning through their senses and gaining motor development coordination. Piaget divided stage 1 into six substages representing different abilities that appear over the first two years of life (Table 3.9).

Substage	Characteristics	Estimated Age
1	Simple reflexes: reflexes begin to be adapted	Birth–1 month
2	Primary circular reactions: infant repeats actions with own body	1–4 months
3	Secondary circular reactions: infant shifts attention to environment, explores it more	4–8 months
4	Coordination of secondary circular reactions: infant starts interacting via goal-directed behavior, coordinating sensory abilities	8–12 months
5	Tertiary circular reactions: child advances to experimenting with environment, goal-directed behavior	12–18 months
6	Beginnings of thought: child starts to use symbolic thought, language, mental representations, and deferred imitation	18 months–2 years

In substage one, Piaget classified reflexes as schemas infants had at birth and then adapted into motor skills as they used them. As the brain develops, infants gain more control over their motor skills and can, for example, suck differently on a pacifier or bottle than on a nipple. Piaget would say the adapting to different cultural tools (objects to suck on) is a way of constructing sucking schemas. In substage two, infants have more motor control and start circular reaction or repeated behaviors. These first circular reactions are considered primary because they involve the infant’s own body, such as infants enjoying sucking their thumbs. The infant can start to integrate skills, such as moving the head and mouth into position for feeding and has more opportunities for building sensory and motor skills.

In substage three, through secondary circular reactions the infant can start to coordinate motor and sensory skills with objects in the environment, such as by shaking a rattle or visually searching for a partially hidden toy. In substage four, the infant has more schemas for different activities and more knowledge of the environment. They may enjoy picking up a light-up toy and transferring it from hand to hand while watching the color change. In essence, they are combining secondary circular reactions to form more complex behaviors. The infant can also now use knowledge and skills for goal-directed behavior. For example, an infant may pull their mother’s hair a second time because they want to hear again that funny noise she made the first time (Figure 3.17). Piaget identified substage four as the time when infants also develop object permanence, the understanding that objects don’t cease to exist when they can’t be observed. For example, if you place a toy under a blanket and the baby lifts the blanket to reach for the toy, this demonstrates their understanding that the toy continues to exist even though it is hidden.

Figure 3.17 In the substages of sensorimotor development, infants learn through circular reactions. They may enjoy such activities as (a) playing with a caregiver’s face to elicit a certain reaction, or (b) squeezing a toy to produce a certain sound. (credit a: “Dad and child” by Kerry Ceszyk/Flickr, CC BY 4.0; credit b: “blue whale” by Sarah Evans/Flickr, CC BY 4.0)

In substage five, the child is an experimenter learning about the properties of an object through tertiary circular reactions (Figure 3.17). What if they drop this toy off the high chair? What if they throw it across the room, bang it on the wall? People may talk about toddlers in this stage as “little scientists.”

In substage six, at the end of the sensorimotor period, two major developments occur: symbolic thought and deferred imitation. First, according to Piaget, symbolic thought is the ability to mentally represent objects, people, or events that are not present. One of the major ways children demonstrate symbolic thought is by using language to describe objects or personal experiences, such as asking for “mama” when she is away at work. Second, children can imitate others after a delay in deferred imitation. For example, an infant might see their sibling eating with chopsticks at lunch and then try to use two markers like chopsticks later when they are playing.

Advances in Understanding of the Sensorimotor Stage

With improvements in our tools and technology for studying infants, we’ve learned that Piaget underestimated their cognitive abilities, and that infants understand object permanence and other qualities of objects earlier than he theorized (Ebersbach, 2009; Woodward & Needham, 2008). For example, to observe the development of object permanence, Piaget hid an object in one place (spot A) several times while an infant was watching. After the infant demonstrated their understanding of object permanence by finding the object in spot A, the object was hidden in a new spot (spot B), again while the infant observed. Despite seeing the object placed in the new hiding place, infants typically looked for it in spot A, making what’s called the A not B error (Figure 3.18). Piaget interpreted this error to mean infants’ understanding of object permanence is still incomplete.

Figure 3.18 When infants find the toy the first time in spot A, they show some understanding of object permanence. However, when they make the A not B error, they may show that their understanding of object permanence has not yet completely developed. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Through newer methods that don’t require the infant to use the motor skill of reaching to find the object, researchers found that infants as young as four months of age can recognize aspects of object permanence (Baillargeon, 1987, Gopnik & Meltzoff, 2021; Meltzoff, 1988). They can also show deferred imitation at as early as six months of age if given opportunities to practice.

Researchers still use Piaget’s tasks to study infant cognition, but in different ways. For example, in Baillargeon and colleagues’ (1989, 2004) A not B task, the researcher hides an object behind one of two screens (spot A), and after a brief delay, the child is allowed to look for it, a visual search task rather than Piaget’s original reach task. After two consecutive looks, the infant must shift attention when the object is hidden behind the second screen (spot B). By 7.5 months, infants can pass the A not B task if the delay is under 2 seconds for reaching or 15 seconds for looking, showing how the type of task can affect the way researchers study and understand infants’ abilities (Baillargeon, 2004; Diamond, 1985).

Piaget was one of the first psychologists to develop a comprehensive theory of the way children develop, an impressive achievement when you consider that most of his ideas came from simply observing children and taking detailed notes. Even decades later, child development researchers support many of his basic ideas. His theory changed our understanding of children’s development and became the foundation for subsequent theories of their cognitive development.

Link to Learning

Piaget tested object permanence in babies by using a manual reach task with a toy and blanket. This toy and blanket method is replicated in this video, but other tasks can also assess this skill, as shown in this clip.

Information Processing and Memory Development

Although infants cannot talk, psychologists can learn much about their information processing by observing them. What is the infant looking at? For how long? If shown the same image again, will the infant look away? If shown again later, will the infant remember it? Studying infants’ looking patterns, or shifts in attention, improves our understanding of their cognitive development. Information processing theory examines the way the human brain works, including in making attention and memory possible.

The Development of Attention

Researchers study different aspects of attention: when we attend, how long we can pay attention, when we might get distracted or disengaged, and when we are able to focus on one thing but ignore another. All these abilities start developing at a young age.

One aspect of infant attention is alertness. Infants spend less than 20 percent of the day in an alert state (Colombo, 2001), with the bulk of their time spent in sleep or rest. Extended alertness or sustained attention occurs when we hold our attention to the stimulus or task (Colombo, 2001). Infants rapidly develop their ability to direct and sustain attention over the first year (Colombo, 2001). Caregivers’ attention and external stimuli like lights and sounds can support alertness in newborns. At around four months of age, the beginnings of attentional control are evident as the infant gains the ability to shift focus (Colombo, 2001; Hendry et al., 2016). At around nine months, infants show a significant increase in control and focus (Colombo, 2001; Hendry et al., 2016).

Link to Learning

Since infants can’t tell us what they are interested in, researchers use creative methods to measure their attention. One such means is an eye tracker that measures looking time, as this video shows.

The Development of Memory

Studying memory in infants can be quite the challenge. Try for a moment to recall your earliest memory. Do you truly remember it? Or is it a story someone in your family has told so often that you feel like you remember it? How old were you? Many of us cannot recall things from our infant and toddler years, a trait known as infantile amnesia. Memory requires a range of cognitive skills as well as brain and language development (Occhionero et al., 2023). Short-term memory is the ability to store information in our mind temporarily, while long-term memory consists of more permanent retention of information and skills. Researchers use several ways to identify the memory abilities of preverbal children.

Cognitive development researcher Carolyn Rovee-Collier helped reveal just how impressive infant memory capabilities and learning can be through the mobile task (Rovee-Collier, 1999). In this task, the kick rate of a two- to six-month-old infant in a crib is measured to establish a baseline. Then a ribbon is secured around the infant’s ankle and attached to an overhead mobile. As the infant kicks, the mobile moves. Infants are then brought back to the lab after various delays, from one day to around two weeks. If their kicking response resumes, it indicates they remember the task. This study showed that even three-month-old infants could remember how to move the mobile for up to one week (Giles & Rovee-Collier, 2011). As babies age, the length of time they can hold information in memory increases from less than a day at two months of age to thirteen weeks at eighteen months of age (Rovee-Collier & Giles, 2010).

Sometimes we remember things more easily if given a reminder or prompt. For example, infants are often able to remember longer if given a reminder of the task or a context clue, such as using the same mobile design in the mobile task (Courage & Cowan, 2022). In other words, cues in their environment help their learning and memory. This research demonstrates that implicit memory, or memory that is not part of our consciousness, is present in infancy. Memory we consciously remember and recall, known as explicit memory, is more fragile in infancy, which helps explain why so many of our earliest memories begin later, in early childhood.

Infant Cognition and Habituation

We can study infant cognition by observing infants, assigning them various tasks, and applying newer technologies including eye-tracking equipment and EEGs (Figure 3.19). EEGs provide an ongoing assessment of the electrical activity in the brain in response to a sensory or cognitive event. Eye-tracking measures what the infant is looking at, for how long, whether attention shifts, and where. Eye tracking can also measure pupil dilation, which indicates attention. Another measure of infant cognition is heart rate. When a baby is paying attention to a stimulus, their heart rate decreases. By using multiple methods, researchers can get a clearer understanding of how the infant is processing information, what they attend to, and what interests them.

Figure 3.19 Technology such as EEG equipment allow researchers to study sleep and cognition in infants and toddlers. (credit: “EEGCCap” by Eric & Laurel Glenn/Flickr, CC BY 4.0)

Observing infant’s habituation, or decreased interest in and response to repeatedly presented stimuli, can also inform our understanding of infant cognition, learning, and attention. Habituation paradigms and visual preference methods measure how rates of responsiveness to a stimulus decrease as infants learn or process information across multiple exposures. In this procedure, a visual or auditory stimulus is presented, and the infant’s attention to it is measured in terms of either increased looking time (eye gaze), increased sucking frequency, EEG pattern changes, or decreased heart rate (Colombo, 2001; Phelps, 2005). As infants habituate or become familiar with the stimulus, they look away from repeated presentations at faster and faster rates, suck more slowly, or have an increased heart rate. When infants habituate quickly, they are demonstrating efficient information processing.

Link to Learning

This video demonstrates an infant losing interest in a toy, known as habituation. Observe the infant’s response when the toy is replaced with something new.

What happens if we show an infant two different objects? In the preferential-looking technique, researchers note which object the infant pays attention to, giving insights into their interest and attention. If the choice is between a novel object and a familiar one, infants will typically look longer at and pay greater attention to the novel object (Colombo, 2001; Yu & Smith, 2016). When an infant gets bored and throws a favorite toy aside, they may simply be showing that learning has occurred.

The amount of time it takes infants to process new stimuli is related to later intelligence. Several studies have associated faster habituation with improved performance on intelligence assessments, including reasoning and verbal abilities in early childhood and elementary school (Bornstein & Sigman, 1986; Fagan et al., 2007; Poli et al., 2024; Sigman et al., 1991). Observing infant habituation can also give health-care providers, researchers, and caregivers insights into an infant’s speed of processing various sensory information (sight, sound, touch), their learning and memory, and their overall cognitive development (Sicard-Cras et al., 2022). For example, a child who shows slower habituation to visual stimuli (being shown a toy) in comparison to tactile stimuli (holding the toy) may need to have their visual acuity checked.

Sociocultural Theory of Cognitive Development

Lev Vygotsky (1896–1934), who developed his theory around the same time as Jean Piaget, was particularly interested in the role of the social environment and culture in cognitive development and learning. In his sociocultural theory, Vygotsky proposed that children learn about the world and develop cognitively from their interactions with caregivers, other adults, peers, and the culture at large (Vygotsky, 1978). Cultural tools play an important role too and include language, systems of counting, memory techniques, art, writing, maps (Vygotsky, 1998), and, more recently, computers, cell phones, and other modern technology. Like Piaget, Vygotsky assumed children construct their own knowledge, but he made a stronger claim that the cultural and social environments were an inseparable part of learning.

For a child to construct their knowledge and learn, Vygotsky believed, they must be nurtured or guided by more knowledgeable people like adults, older children, or peers, and they must be aware that what they’re learning is important. As you recall from 1.3 Major Theories and Theorists, he called this process scaffolding and used the concept of the zone of proximal development to describe how scaffolding can advance cognitive growth in children. During scaffolding, the child’s cognitive partner uses language for scaffolding (social speech). Over time, children will begin using their own language as the basis for their cognitive development. They will talk to themselves as they work through a challenge, in what we call private or egocentric speech, aloud at first but then silently. For example, a child learning to put together a puzzle may mutter, “First, find the corner and edge pieces.” But as their puzzle experience grows, they may simply mentally remind themselves of that step. In short, they have internalized the skills acquired through scaffolding and can now independently demonstrate a new skill or knowledge.

Language isn’t the only means of guiding young children’s learning, since children also learn by observing others and copying their behaviors. The learning process may also include social referencing, the use of information from others to determine how to respond to a situation (Ehli et al., 2020). For example, an infant may use an adult’s facial expression, such as a stern look, as a social reference before climbing over the baby gate (or not). A caregiver can also guide an infant’s learning indirectly by placing toys nearby for the child to explore. If the infant seems unsure, the parent can use facial expressions and tone to show their feelings about the toy.

Variations in Cognitive Development

Recall the reliance on WEIRD (White, educated, industrialized, rich, and democratic) samples for much of the research on child development. The theories of cognitive development you’ve just studied were developed by studying middle-class children in WEIRD cultures. However, the cognitive development of young children is influenced by many variables, including environmental and cultural influences.

Culture

Even before birth we are immersed in culturally shaped environments. Families and others in the home frame our exposure to language, values, and norms and transmit culture through daily interactions. Family traditions, values and expectations, religious practices, holidays and celebrations, and exposure to education and the media bring specific knowledge and experiences to the child. For example, adults in the non-Western indigenous community of Vanuatu emphasize physical contact with infants more than visual, face-to-face contact, which is emphasized in Western cultures such as the United States (Little et al., 2016).⁴ In rural Africa, Kipsigi mothers carry their infants on their backs most of the day (Super & Harkness, 2002). This close body contact gives infants time to observe what their parents are doing, influencing their cognitive and emotional development (Bánovský, 2023).

Socioeconomic Influences

Family socioeconomic status (SES) can also play a role in early cognitive development. Together, factors like caregiver education and family access to resources have consistently been found to influence cognitive development, including language, memory, and executive functions (Blair & Raver, 2016; Farah et al., 2006; Weisleder & Fernald, 2013).

Children from families of low-SES consistently score lower than others on measures of cognitive ability and academic achievement (Lurie et al., 2021). Their families often have less access to educational resources, and poverty has been shown to harm the developing brain by increasing stress and reducing opportunities (Blair & Raver, 2016; Tarullo et al., 2020). But the way in which SES influences cognitive development is complicated.

Socioeconomic status is associated with access to books, exposure to environmental hazards, language exposure, the quality of parent-infant interactions, and parental warmth and sensitivity. Mothers with higher SES are more likely to have healthier lifestyle habits during pregnancy, smoke less, and exhibit less sedentary behavior (Larranaga et al., 2013). Parents with lower SES may be less confident in their parenting skills (Liu et al., 2020). The level of maternal education, an important component of SES, is one of the strongest predictors of child development (Pace et al., 2017), likely because it is strongly associated with other resources that affect child development, such as financial security, family structure, and maternal depression (Jackson et al., 2017).

What can we do to protect children in families with lower SES? We know high-quality early childhood care and education can provide many benefits (Davis & Dunn, 2022). Interventions that support parents and give them strategies for interacting with their infants at home can also be helpful (Company-Cordoba et al., 2021).

Home Environment

Home is where young children typically spend most of their time. Aspects of the home environment include parent-child interaction and support, caregivers’ promotion of autonomy, respect for the child, use of rules, and overall home environment quality (Bradley & Caldwell, 1982). A study of Malaysian infants aged twelve to thirteen months showed that infants in a low-quality home environment scored lower on cognitive tests than their peers with higher-quality home environments (Nurliyana et al., 2020). Quality of home environment has been related to cognitive development after one year, through the preschool years, and in later intellectual development (Totsika & Sylva, 2004). In fact, the home environment has been found to be a greater influence on neurodevelopment at eighteen months than SES and maternal IQ (Ronfani et al., 2015). Ultimately, the quality of infants’ experiences within the home can indicate whether any interventions should be targeted to individual families.