Applied History of Psychology/Cognitive Development

Jean Piaget
From the 1920's through 1960's, behaviorism was the dominant force in psychology. However, psychologists eventually began to move away from strict behaviorism and move towards an emphasis on cognition or mental processes. This shift is often referred to as the "cognitive revolution" because the emphasis on cognition had such a profound influence on psychology. Much of this can be attributed to the work of Jean Piaget.

Born on August 9, 1896 in Neuchâtel, Switzerland, Jean Piaget, a Swiss philosopher, natural scientist and developmental psychologist began his career as a biologist at the early age of ten, when he published his first paper - a one-page report about his sighting of an albino sparrow. Piaget's interests in science soon began to reflect a deeper curiosity around science itself and the thinking involved in practicing science. It is from these beginnings that Piaget became interested in the nature of 'thought' and the development of 'thinking' and his work in this area resulted in one of the most famous and widely-accepted theories of cognitive development.

The Piagetian Model of Children's Thinking


 * Sensorimotor Period (birth to 2 years)
 * Key ideas in cognitive development at this stage:
 * Coordination of sensory input and motor responses
 * Development of object permanence
 * Little or no capacity for symbolic representation
 * Milestones:
 * Birth to 1 month: Child displays modification of reflexes to make one more adaptive.
 * 1 to 4 months: Primary circular reactions and coordination of actions occur.
 * 4 to 8 months: Child displays secondary circular reactions but will not search for hidden objects.
 * 8 to 12 months: Coordination of secondary circular reactions. The infant can retrieve hidden objects but continues searching where objects were previously found rather than where they were last hidden (A not B error).
 * 12 to 18 months: The child engages in tertiary circular reactions. The baby will systematically vary the height from which he/she drops things.
 * 18 to 24 months: The child is beginning to form true mental representations. There is deferred imitation.


 * Preoperational Period (2 to 7 years)
 * Key ideas in cognitive development at this stage:
 * Development of symbolic thought
 * Irreversible, egocentric thinking
 * Milestones:
 * 2 to 4 years: Development of symbolic capacities, as indicated by language, make-believe play, drawings, and understanding of spatial symbols. Growth of language and mental imagery occurs but communication remains egocentric.
 * 4 to 7 years: Child has good language and mental imagery skills, but an inability to represent transformations. She/he focuses on single perceptual dimensions in conservation, class inclusion, time, seriation, and other problems. The child also replaces magical beliefs about fairies, goblins, and events that violate expectations with plausible expectations and shows improved ability to distinguish appearance from reality. They are capable of creating more realistic drawings, which begin to depict the third dimension.


 * Concrete Operational Period (7 to 12 years)
 * Key ideas in cognitive development at this stage:
 * Mental operations applied to concrete objects and events
 * Development of conservation, mastery of concept of reversibility
 * Milestones:
 * Whole period: The child can now perform true mental operations, represent transformations and static states, and solve conservation, class, inclusion, time, and many other problems. She/he still has difficulty thinking of all possible combinations and transformations.


 * Formal Operational Period (12 years through rest of life)
 * Key ideas in cognitive development at this stage:
 * Mental operations applied to abstraction
 * Development of logical and systematic thinking
 * Milestones:
 * Whole Period: The adolescent can think about all possible outcomes, interpret particular events in terms of their relation to hypothetical events, and understand abstract concepts such as conservation of motion and chemical interactions.

Criticisms of Piaget's Stage Model

Although it is undeniable that Piaget’s work was highly influential and groundbreaking, it is not without criticism. Some theorists and developmental psychologists actually question whether or not development occurs in the stagewise fashion as Piaget suggested; that is, is cognitive development in children all or nothing (e.g. a child is either in the sensorimotor stage or the preoperational stage but not between) or do cognitive structures and abilities develop more gradually? These developmental psychologists point to experimental research that demonstrates that children can actually accomplish certain tasks earlier than Piaget would have thought.

For example, the work of Renee Baillargeon (1987) has demonstrated that the concept of object permanence may actually develop much sooner than the age of 8–12 months (as Piaget would have predicted). Object permanence is usually studied by showing an infant a highly desirable toy and then removing that toy and hiding it from view (for example, under a blanket). After viewing the toy being placed under the blanket, Piaget showed that infants as young as eight months would attempt to reveal the toy by pulling off the blanket. Piaget posited that this action demonstrated that the infant understood that the object continued to exist even though it was out of sight. Infants younger than eight months rarely attempted to remove the blanket, demonstrating that they failed to understand that the object continued to exist when hidden.

Baillargeon believed that infants younger than eight months failed Piaget’s task because they were lacking in the gross and fine motor movement required to reach out and remove the blanket from atop of the toy. As a result, Baillargeon (1987) designed a study to test object permanence that did not require a motor movement from the infant. In her study, Baillargeon (1987) seated a child in front of a large rotating cardboard screen. She showed the infant several trials of the screen moving back and forth in a 180 degree motion (starting flat on the table and moving away from the child until it again came to rest flat on the table). On some trials Baillargeon placed a block behind the rotating screen. On these trials the screen would rotate away from the child and come to rest on the block (moving only approximately 110 degrees) (possible task). Finally, on some trials the block was placed in sight but then as the rotating screen blocked it from view it was removed, allowing the screen to rotate the full 180 degrees and seemingly right through the block (impossible task). Results from this study revealed that infants as young as three and a half months looked significantly longer at the seemingly impossible task when compared to the possible tasks (screen resting on the block or screen rotating through air). Baillargeon (1987) interpreted this longer looking time as evidence that the infants knew that the block continued to exist even though it was blocked from view and that they were ‘shocked’ that the screen seemingly rotated right through it.

Another task that Piaget is famous for involves having an experimenter show an infant a highly desirable toy and place it within reach of either their left or right hand. The placement location of the toy is referred to as ‘Location A.’ The desirable toy is then covered with an object, such as a blanket, and the infant is given the opportunity to retrieve the toy. After hiding and retrieving the toy several times at Location A, the experimenter moves the toy to the opposite side of the child (but in view of the child). This is referred to as ‘Location B.’When the toy is hidden again, and the child is given another chance to retrieve it, surprisingly infants between 8 and 12 months of age reach for Location A rather than Location B! This is what Piaget called the ‘A not B Error.’

But many child development researchers following Piaget have questioned whether infants really do not understand that the toy has moved locations and that it now exists elsewhere. It was noted that a small percentage of infants in Piaget's studies actually looked at Location B (where the toy was) while reaching for Location A. These observations lead other researchers to come up with and use a novel design – termed the 'violation of expectancy paradigm' - to further test Piaget’s notions about young infants’ ability to search for objects and their memory for object location.

Ahmed and Ruffman (2000) conducted a series of three experiments to further explore the A not B errors that infants make. In their first study the authors attempted to replicate the results of Piaget’s original task, requiring infants to search for an object using a motor response. In the second study the authors used a ‘nonsearch task.’ Here the infants saw a toy being hidden and retrieved at Location A by an experimenter. Then the infant watched the experimenter move and hide the toy at a new location – Location B. The toy was then retrieved by the experimenter from Location A (impossible event) or Location B (possible event). If the infants understood that the toy was at Location B, retrieval from Location A should violate their expectancy and as a result, infants’ looking times should be longer for the impossible rather than the possible event. In the third study the authors used a nonsearch task that only involved one location. Infants were shown the toy only being hidden and retrieved from Location A. The violation of expectation would be when the experimenter retrieved the hidden toy from Location B (a location in which the toy was never hidden).

Results from these studies showed that tasks requiring a motor response replicated Piaget’s early findings, that is infants made the A not B error (Ahmed & Ruffman, 2000). However, when tasks did not require a motor response, infants who were aged 8 to 12 months looked longer at impossible events when compared to possible events – inconsistent with the A not B error (Ahmed & Ruffman, 2000). Together these results suggest that the ability to remember the location of objects develops prior to 8 to 12 months and earlier than Piaget believed.

Lev Vygotsky
Lev Semyonovich Vygotsky was born in Russia in 1896. In 1916, he graduated from Moscow University with a degree in Law and later worked in his native town of Gomel before he moved in Moscow in 1924, where he lived until his death in 1934. At the same time Piaget was working on his theory, this pioneering psychologist brought a new perspective to cognitive development research that stressed the importance of social interaction to cognitive growth. While his work was left incomplete after his unfortunate death at the age of 38, Vygotsky’s cultural-historical theory of higher mental functions development has had a significant impact on the history of the cognitive sciences. Often compared and contrasted with Piaget’s cognitive-developmental theory, the sociocultural perspective challenges Piaget’s universalist notion of development in favour of a cultural relativist approach that considers specific cultural context and social interactions, with a particular emphasis on belief systems, language structure and social environment.

The main principles of his sociocultural theory suggest:
 * That cognitive growth occurs within a sociocultural context that affects its form and processes.
 * "Many of a child’s cognitive skills evolve from social interactions with parents, teachers, and other more competent associates” (Shaffer, 1999, p. 259).
 * Language plays a central role in mental development.

Vygotsky claimed that infants are born with very few elementary mental functions – attention, sensation, perception and memory – that are eventually stimulated and nurtured by culture, developing into new and more sophisticated mental processes he labeled “higher mental functions” (Shaffer, 1999). He suggested that each culture transmitted beliefs, values, and preferred methods of thinking and problem-solving which were then internalized by its children. Thus, culture played a significant role in teaching younger generations what to think and how to go about it. Vygotsky categorized these types of cultural information as “tools of intellectual adaptation” which allowed elementary mental functions to be adapted more readily to the particular social environment (1978).

The central tenant of sociocultural theory indicates that children acquire cultural information in the context of collaborative dialogue and exchange with a more knowledgeable partner. The child learner begins to internalize the directions of the instructor in order to complete tasks which are otherwise too complex to be completed by the child alone. While Vygotsky agreed with Piaget that children were actively involved in learning and discovery, he placed less importance on self-initiated discovery choosing instead to focus on the contributions of social interaction or dialogue (Shaffer, 1999). Within Vygotsky’s framework, truly important discoveries occur when the learner is operating within the “zone of proximal development”; that is, where the encouragement and instruction of a skillful tutor can push the learner’s level of accomplishment well beyond the level attained through independent discovery.

Vygotsky’s sociocultural theory also raised significant questions about the relationship of language and thought. From his perspective, language:
 * Is the primary vehicle through which adults pass cultural systems of thought and problem-solving on to their children.
 * Is one of the more powerful tools of intellectual adaptation.

Of particular importance was Vygotsky's view on the significance of verbal self-directed utterances of pre-school aged children as it contrasts sharply with Piaget’s perspective.

Egocentric Speech (Piaget) vs. Private Speech (Vygotsky)

Both theorists recognize the pre-school child’s self-directed monologues but disagree on the significance of such verbal expressions to the child’s cognitive development. Piaget regards this as “egocentric” – merely reflecting the child’s ongoing mental activity. On the other hand Vygotsky recognized such self-directed speech as communicative rather than egocentric; it is “speech for self” or “private speech” (Shaffer, 1999, p. 265). He suggests that this type of speech helps young children to plan strategies and regulate their behaviour so that they are more likely to accomplish their goals. As such, language plays a critical role in cognitive development by helping children organize their thoughts and become more proficient problem solvers. Further, Vygotsky’s position suggests that this early speech pattern or “private speech” never fully disappears, but becomes a silent inner speech that serves as a “cognitive self-guidance system” used to regulate everyday behaviour in later years.

Vygotsky’s sociocultural theory has greatly impacted the historical trajectory of developmental psychology as it has posed a strong challenge to universalist notions of cognitive development and has reminded us that cognitive growth is best understood within the cultural and social contexts in which it occurs.