Difficulty: Introductory to Intermediate | Prerequisites: Piaget's sensorimotor period (substages I through VI)
This material covers the physical and cognitive milestones of the first two years, with a focus on how motor skills develop (walking, surface awareness), Piaget's circular reactions, infant memory, and early self-regulation (toilet training, verbal self-comfort). You need a solid grasp of Piaget's sensorimotor substages before this section will make full sense. If you cannot distinguish primary from tertiary circular reactions, start there.
Infants walk better when carrying objects and need awareness of walking surfaces for advanced motor skills. Piaget's circular reactions (primary, secondary, tertiary) describe how infants explore the world in progressively more deliberate ways. Thirteen-month-olds can remember actions they have only observed (not performed) for at least two weeks. Western cultures likely delay toilet training beyond when infants are physically ready.
Primary circular reactions
Simple, repetitive actions centred on the infant's own body, occurring in Piaget's sensorimotor substage 2 (roughly 1 to 4 months). The infant repeats an action for its own sake, such as sucking a thumb.
Think of it as: the baby does something with their own body, likes it, and does it again.
Secondary circular reactions
Repetitive actions directed at external objects, occurring in substage 3 (roughly 4 to 8 months). The infant repeats an action to reproduce an interesting effect in the environment, such as shaking a rattle.
Think of it as: the baby discovers that something they do makes something happen out there, and keeps doing it.
Tertiary circular reactions
Deliberate experimentation with variations, occurring in substage 5 (roughly 12 to 18 months). The infant intentionally varies actions to observe different outcomes, such as dropping objects from different heights.
Think of it as: the baby becomes a little scientist, trying things in different ways to see what happens.
Coordination of secondary circular reactions
Combining two previously learned schemes to achieve a goal, occurring in substage 4 (roughly 8 to 12 months). For example, pushing aside a barrier to reach a toy.
Deferred imitation
The ability to observe an action and reproduce it after a delay. By 12 to 18 months, infants can watch a multi-step sequence and re-enact it a week later.
Zone of proximal development (ZPD)
Vygotsky's concept (see Language Development notes). It is domain-general, not language-specific.
Infants walk better when they are carrying something in their hands. This is a counterintuitive but tested finding
An important ingredient of advanced motor skills is being aware of the type of surface one is walking on. Surface awareness feeds into balance and movement decisions
Primary circular reactions: body-centred repetition (substage 2). The source material's exam answer identifies a baby hitting drumsticks on various objects as primary circular reactions, though note this scenario has features that could suggest tertiary reactions (deliberate variation). Follow your course's classification
Secondary circular reactions: object-directed repetition to reproduce interesting effects (substage 3)
Coordination of secondary circular reactions: combining schemes to solve problems (substage 4)
Tertiary circular reactions: deliberate experimentation with variation (substage 5)
13-month-old infants can remember an action task even without having performed it themselves. The claim that they "cannot remember unless they perform the action" is false
Between 12 and 18 months, infants can watch an adult perform a multi-step cleaning sequence (wipe, dry, throw away) and re-enact it a week later. This demonstrates deferred imitation
During this same period, infants can correctly categorise toy animals and cars into two groups and find new ways to fit shapes into a box
Between 18 and 24 months, children do not yet have the ability to comfort themselves verbally
Infants are probably able to be toilet trained well before it typically occurs in Western culture. Cultural norms, not physical readiness, drive the timing
Students often think infants walk worse when their hands are occupied. The opposite is true: carrying something actually improves walking
Students sometimes believe 13-month-olds must physically perform an action to remember it. They can remember observed actions without performing them, and retain them for at least two weeks
The drumstick scenario in the source material is labelled as primary circular reactions, but its features (hitting different objects to hear different sounds) look like experimentation. Follow your professor's classification, but be aware this is a tricky item
Students may assume that toilet training timing is driven by physical readiness. In Western culture, the delay is largely cultural, not biological
⚠️ "Infants walk better when carrying objects" is a commonly tested true/false item
⚠️ Distinguishing primary, secondary, and tertiary circular reactions is a staple multiple-choice topic. Know the substage numbers and the key feature of each
⚠️ The 13-month memory question (can they remember without performing?) is tested as true/false. The answer is false, as they can remember without performing
⚠️ The 12 to 18 month abilities (categorisation, shape-sorting, deferred imitation of multi-step sequences) appear as "all of these" multiple-choice items
⚠️ Toilet training readiness vs cultural timing is a true/false favourite
True or false: Infants walk better when carrying something in their hands. (Answer: True)
True or false: 13-month-olds cannot remember an action unless they perform it themselves. (Answer: False)
Which Piaget substage involves deliberate experimentation with variations? (Answer: Substage 5, tertiary circular reactions)
True or false: Between 18 and 24 months, children can comfort themselves verbally. (Answer: False)
True or false: Infants could probably be toilet trained earlier than Western culture typically allows. (Answer: True)
Q: Baby Ty hits drumsticks on the drums, then starts hitting them on chairs, floors, and boxes to listen to the different sounds. Which type of circular reaction does the source material identify this as?
A: Primary circular reactions (per the source material's answer key). Note that the deliberate variation in this scenario has features resembling tertiary circular reactions. Follow your course's classification.
Q: True or false: 13-month-old infants cannot remember an action task unless they have a chance to perform the action themselves.
A: False. They can remember observed actions without performing them and retain them for at least two weeks.
Q: What abilities can be seen during the 12 to 18 month period?
A: All of the following: correctly categorising toy animals and cars into two categories, finding new ways to put shapes into a box, and watching an adult perform a multi-step cleaning sequence and re-enacting it a week later.
Q: Can children between 18 and 24 months comfort themselves verbally?
A: No. Verbal self-comfort is not yet available at this age.
Q: Are infants physically capable of toilet training earlier than it typically occurs in Western culture?
A: Yes. The delay is driven by cultural norms rather than biological readiness.
Piaget's circular reactions connect directly to the sensorimotor period covered earlier in the course. The progression from primary to tertiary reactions maps onto the infant's growing intentionality and problem-solving ability, which in turn feeds into later cognitive milestones like symbolic thought.
Motor development (walking, surface awareness) connects to the play and peer interaction material: an infant who walks confidently can engage more actively with peers and objects. The self-regulation content (verbal self-comfort, toilet training) foreshadows the emotional regulation topics covered in later developmental stages.
Primary circular reactions, secondary circular reactions, tertiary circular reactions, coordination of secondary schemes, Piaget sensorimotor stages, deferred imitation, infant memory, infant walking, surface awareness, motor development, toilet training readiness, verbal self-comfort, 12 to 18 months, 18 to 24 months, PSY 3215, developmental psychology, infant cognition