1.3 Major Theories and Theorists

Stage Theory of Cognitive Development

Swiss biologist Jean Piaget is famous for contributing theories regarding changes in cognitive ability that occur as we move from infancy to adulthood. He spent his early years as a scientist studying various animals. He then worked on creating some of the earliest measures of intelligence. As he was writing test items, he interviewed children and asked them to explain the thought process behind their answers to sample questions. One of Piaget’s early insights was to focus on the children’s incorrect answers because they provided a window into their reasoning abilities. From these observations, he developed his prominent stage theory of cognitive development (Piaget, 1952, 1954). Piaget’s theory, like Erikson’s, is an organizing framework for the modern study of lifespan development.

Piaget’s theory views development as occurring through a series of age-based stages (Table 1.2). As we age and our brain and bodily systems mature, we are afforded new ways of interacting with the world. The combination of these new physical and sensory capabilities with the new experiences the environment offers drives the development of thinking abilities that are acquired across the first twenty years or so of life. Along the way, individuals are active participants in their own development, testing out ideas and capabilities in the world and formulating a coherent sense of how the world works. Piaget’s emphasis on the active nature of learning and development, his focus on the reasoning behind wrong answers, and his delineation of the psychological processes occurring in cognitive development made for a groundbreaking theory.

Sociocultural Theory of Cognitive Development

Russian psychologist Lev Vygotsky explored learning and cognitive development in children during the early twentieth century, and demonstrated how important social interaction is for learning and growing. He died in his thirties and his work did not become widely known outside Russia until the 1970s, when his theory became very influential in the field of developmental psychology.

Vygotsky (1978, 1998) proposed a sociocultural theory of cognitive development, emphasizing that thinking abilities are embedded within an individual’s social and cultural context. Whereas Piaget’s theory focused on a person’s step-like journey of coming to understand the world, Vygotsky saw cognitive development as supported and propelled by social tools available to the individual learner. These social tools include language, direct support from others, and technological aids. Vygotsky, then, was among the first to recognize that language guides cognition and gives shape to ideas that can be readily communicated with others through words. One such example is private speech, whereby the learner may use words to audibly (or not) keep themselves on track during a difficult problem-solving session. If you’ve ever rehearsed a list of grocery items out loud while you searched for a place to record them, you’ve used language in such a way. Acronyms for remembering complex math concepts, such as PEMDAS (parentheses, exponents, multiplication, division, addition, and subtraction) for the order of arithmetic operations, are another example of language use supporting cognition.

The application of various forms of technology, another social tool, can allow an individual to perform complex tasks more easily than by relying on brain power alone. From this perspective, using a calculator to do basic calculations frees up the mind to think about the more important and complex parts of a word problem, for example. Word processing programs and apps that autocorrect spelling and grammar support thinking by allowing the writer to focus on the ideas of their message, instead of on the mechanics of writing.

Vygotsky is best known for championing social supports in propelling cognitive development and educational achievement. His notion of the zone of proximal development (ZPD) states that all of us are capable of thinking and achieving at a higher level than we may realize: there are concepts and ideas just beyond our current abilities that we are ready to master if only we have a little help, often from others. Educators and parents have used the idea of scaffolding to help learners achieve beyond their current level, gradually withdrawing support as the student becomes more competent. Learning how to ride a bicycle is a great example of scaffolding. Support for learning this difficult task can come through training wheels, or from a caregiver holding the bicycle seat while running alongside the child. As the child gains a sense of balance and masters the mechanics of pedaling and steering, the training wheels become less necessary and are eventually removed, and the caregiver lets go of the seat. The child has reached a new level of development with guided and temporary support.

Information Processing Theory

Our digital age has also brought new ways of thinking about how the human brain works. Although the computer was conceptualized via ideas about how the human brain functions, psychologists now use the functioning of a computer as a metaphor for understanding how we think.

From the 1960s onward, the metaphor of information processing has been a helpful way to think about cognition and cognitive development (Atkinson & Schriffrin, 1968). One key concept is that of information flowing into the brain, being processed or acted on, and then leaving the brain in the form of behavioral output, just like data in a computer. This concept also relies on a modular view of the brain: the idea that discrete structures within our brain specialize in various cognitive tasks, such as memory, sensory processing, language comprehension, and spatial reasoning. As information flows into the brain through various senses, it is routed to the appropriate brain region and acted on, and then behaviors emerge through actions and words. From a developmental perspective, cognitive development is fostered as the various parts of this information processing system mature and gain operational efficiency.

While the information processing model is useful, it has also become more simplistic as science has progressed. Our brain indeed has many functional modules that are connected and share information back and forth. The advent of brain imaging technology brought insight into further complexities of how the brain and its cognitive abilities are organized.

Cognitive Neuroscience

Advancement in computing technology ushered in increasingly sophisticated ways to image, or view, the brain. At first, technologies such as x-rays and CT-scans (computed tomography scan) were used to make images of brain structures. Often, researchers would correlate brain injury and loss of functionality with changes seen in these images. The invention of MRI (magnetic resonance imaging) scanning made highly detailed imaging possible. Finally, an innovative software development allowed many such images to be made quickly and spliced together into a real-time video of the brain at work. This technique is called fMRI (or functional magnetic resonance imaging.)

Together, these are imaging tools that psychologists working in cognitive neuroscience use to connect brain structure and function with behavior. Scientists can now see which areas of the brain become more active when participants solve math problems, think about a romantic partner, or perform a memory recall task, among many other fascinating findings (Figure 1.9). Periodic brain scans allow researchers to observe the effects of learning and mastering a challenging task over time, and to look for changes in connectivity among various brain regions as individual’s age. The Dallas Lifespan Brain Study (DLBS) is an example of the advances made by using these technologies to think about the aging brain. For example, contrary to the expectation that brain changes and symptoms of Alzheimer’s disease and other forms of dementia begin in late adulthood, research from DLBS has shown a steady relation between changes in the brain and a decline in cognitive function beginning much earlier in adulthood (Smith et al., 2023). This provides hope for advancements in the identification, prevention, and treatment of these diseases.

Figure 1.9 Psychologists use fMRI (functional magnetic resonance imaging) to learn more about which areas of the brain respond to different stimuli. (credit: modification of work “Haxby2001” by US Department of Health and Human Services: National Institute of Mental Health/Wikimedia Commons, Public Domain)

Ethology

The study of animal behavior is called ethology. Developmental psychologists who use this approach study animals, especially other mammals, as models to discover and test ideas relevant to understanding human functioning. In 1930s England, John Bowlby used his medical and psychoanalytic training to research the experience of children growing up in orphanages and similar institutions. Even though these children had all the physical necessities for health—clothing, shelter, and food—he was concerned by the emotional and social effects he observed. Using these observations and his findings from animal studies, including rodents and monkeys, Bowlby formed the theory of attachment, an enduring, emotionally significant bond that forms between two individuals, often in a caregiving context (Bowlby, 1951). The development of at least one attachment, the basis of human bonding, is essential to human development. Bowlby’s discovery of this necessary component for human flourishing opened a new area of developmental inquiry with far-ranging consequences for individuals across the entire lifespan.

Evolutionary Psychology

The approach of evolutionary psychology looks to the theory of natural selection to explain the emergence, development, and persistence of various psychological characteristics in humans. Natural selection posits that long-ago environmental conditions favored those with certain physical and psychological characteristics making them more likely to survive and be able to reproduce. These individuals could then pass on their genes, coded for those characteristics, to their offspring. Across many generations, the characteristics that conferred such a survival advantage became part of the species’ genetic package. Examples of human functioning that have been studied from an evolutionary perspective include aggression and prosocial (helping) behavior, mating preferences, attachment, wisdom, the timing of puberty, and sleep patterns, among many others.

Behavioral Genetics

The field of inquiry that most directly explores the intersection between nature and nurture is called behavioral genetics. Research in this area helps to explain how much variation in a psychological characteristic is due to genetic differences among individuals, which will shape the kinds of interventions and other applications science can offer.

To measure the heritability estimate for a given psychological characteristic, researchers frequently use a kinship study, which examines how genetic and environmental similarities between individuals relate to differences in their traits or behaviors. In twin studies, a type of kinship study, the correspondence between the genetic relatedness of twins specifically (both identical and fraternal) and resulting psychological characteristics are examined (Figure 1.10).

Figure 1.10 Studying twins helps researchers learn more about how genetics and environment influence various aspects of psychological development. (credit: “Twins” by Shannon Miner/Flickr, CC BY 4.0)

Kinship studies allow psychologists to take advantage of naturally occurring variations in the genetic similarities among individuals and compare that information with what we know about the degree of similarity or dissimilarity in the same individuals’ environments. For example, we know that identical twins who grow up together share close to 100 percent of their genes but also have a high degree of overlap in their upbringing. Fraternal twins, like any non-identical set of siblings, share approximately 50 percent of their genes, and have considerably more environmental overlap than non-twin typical siblings who may be born years apart and grow up in different stages or versions of the same household. Studies that observe family members in these contexts allow scientists to discern the relative contributions of genes and environment to the development of psychological characteristics.

Classical Conditioning

Early in psychology’s history as a science, Russian physiologist Ivan Pavlov accidentally uncovered the principles that came to be known as classical conditioning. While studying the digestive system of dogs, Pavlov noticed that his experimental subjects, dogs, would often salivate even when he hadn’t produced the meat powder that was meant to trigger their salivation. The dogs had come to associate the sound of a bell, which signaled the start of each experimental trial, with impending food, and thus they would salivate when they heard the bell, even without the meat powder. Pavlov became curious about this and soon discovered the principles of classical conditioning.

In classical conditioning, a neutral or meaningless stimulus, in the case of Pavlov’s dogs the sound of the bell, takes on the same meaning for the learner as the natural stimulus with which it is accidentally or intentionally paired, in this case the meat powder. As a result, the previously neutral stimulus then produces the same behavioral outcome as the natural stimulus. The natural stimulus, which has inherent meaning like the smell of food, is called an unconditioned stimulus, while the once-neutral trigger is called a conditioned stimulus because the learner has become conditioned to respond to it (Figure 1.11).

Figure 1.11 In classical conditioning, food initially triggers salivation, while a bell does not. After repeatedly pairing the bell with food, the bell alone triggers salivation. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

This type of learning is a form of associative learning, in which the repeated presentation of two stimuli results in linking them, making their meanings synonymous. A language learner’s vocabulary can be built this way (Smith & Yu, 2008). For example, a toddler is presented with an apple and at the same time hears the word “apple.” It doesn’t take many repetitions before the child associates the object apple with the word label “apple.”

Operant Conditioning

B.F. Skinner uncovered fundamental principles of learning theory in the early twentieth century (Skinner, 1938, 1961). Skinner’s studies built on Thorndike's law of effect—the philosophical idea that the consequences of an action tend to alter the frequency of the action (Thorndike, 1911). From this came the understanding of operant conditioning, the theory of learning that outlines how feedback from the environment shapes an individual’s behavior. Essentially, Skinner’s theory explains how behaviors are strengthened or weakened according to their consequences.

According to Skinner’s operant conditioning theory, learning starts with an individual performing a behavior. The environment can then provide encouraging feedback called reinforcement, discouraging feedback in the form of punishment, or a neutral response, including ignoring the behavior. Given positive or negative feedback, the individual learns the value of the behavior and typically modifies its frequency. The practice of shaping gradually builds complex behaviors by rewarding actions that get closer and closer to the desired outcome.

For example, in the case of language development, when a caregiver holds up an apple and a toddler says “appah,” the caregiver may exclaim excitedly, “Yes! An apple!” The next week, though, the caregiver might respond with less enthusiasm and instead repeat, “Apple . . . aaa-pulll.” Only when the child responds with the more accurate “ahpul” would the caregiver give the same enthusiastic praise as before. In this way, speech can be built and shaped over time. Notice the role of rich and varied environmental feedback in producing this type of learning.

Observational Learning

Albert Bandura studied the principles of observational learning that explain how learning can occur through the social act of observing others who are themselves learning (Bandura, 1961). Among Bandura’s contributions are two noteworthy insights to our understanding of human development and learning. First, his work recognized that humans are social animals: we live, learn, and develop within the presence of others, and we are influenced by and influence one another. Second, he demonstrated that the processes of classical conditioning and operant conditioning can guide learning: when we observe others’ actions and the consequences of those actions, we learn too. This indirect or vicarious learning through others is common in today’s media-saturated environment, where we are exposed to the actions and learning of others through our computer screens, smartphones, and televisions (Figure 1.12). Long-running educational television shows like Sesame Street and Dora the Explorer provide abundant opportunities for a child viewer to learn language, for instance, by observing others’ language learning.

Figure 1.12 Learning by viewing others can be powerful. (a) Yoga students learn by observation as their instructor demonstrates the correct stance and movement for students (live model). (b) Models do not have to be physically present for learning to occur, however. Through symbolic modeling, this child can learn a behavior by watching someone demonstrate it on video. (credit a: modification of work “Yoga Class with Ki Steelman” by Tony Cecala/Flickr, CC BY 2.0; credit b: modification of work by Andrew Hyde)

The theories and principles that together make up the behaviorist perspective offer a powerful set of explanations for the development of complex behaviors, capabilities, and characteristics, such as language and personality, especially in response to environmental feedback.