Cognitive Connie
Understanding baillargeon and infant physical cognition
Renée Baillargeon (1951–) transformed developmental psychology by demonstrating that infants possess sophisticated knowledge of the physical world far earlier than Piaget's sensorimotor stage theory predicts. Using looking-time paradigms rather than reaching tasks, she documented surprise-like reactions in infants under 6 months — and eventually under 3 months — when objects violated basic physical principles.
Key figures
Elizabeth Spelke
1949–Harvard developmental psychologist who developed the core knowledge framework, proposing that infants begin life with domain-specific knowledge systems for objects, agents, number, and space. Her habituation research on infant physical reasoning complemented and extended Baillargeon's VOE work, situating it within a broader nativist-leaning theoretical framework.
Adele Diamond
1949–Canadian neuroscientist who provided a complementary account of the A-not-B error, arguing it reflects prefrontal and executive function immaturity rather than conceptual failure — consistent with Baillargeon's competence/performance distinction. Her work integrated developmental psychology with cognitive neuroscience.
Renée Baillargeon
1951–American developmental psychologist at the University of Illinois who, using VOE paradigms, systematically demonstrated that infants possess physical knowledge — including object permanence, solidity, continuity, and gravity — far earlier than Piaget's stage theory predicts. Her research fundamentally challenged nativist/empiricist boundaries in developmental theory.
Key concepts
Violation-of-expectation (VOE) paradigm
The primary methodology in Baillargeon's research. Infants are habituated to a possible event (their looking time decreases with repetition). They are then shown either a physically possible or a physically impossible ("impossible") test event. If infants look significantly longer at the impossible event, this is taken as evidence that they expected the physical event to unfold differently — implying possession of the relevant physical knowledge. Bypasses the motor limitations of reaching tasks by using looking time as the dependent measure.
Object permanence (Baillargeon)
Baillargeon's research revealed evidence for object permanence far earlier than Piaget's 8–12 month estimate. Baillargeon, Spelke & Wasserman (1985) found evidence at 5.5 months using the drawbridge task; Baillargeon (1987) replicated at 3.5 months. The dissociation — infants showing surprise at violated object permanence but still failing reaching tasks — suggests the concept is present but expression is motor-limited. The A-not-B error reflects executive and inhibitory limitations rather than absence of the object permanence concept.
The drawbridge study
Baillargeon, Spelke & Wasserman (1985): infants were habituated to a drawbridge rotating 112° back and forth. They were then shown either a possible event (drawbridge stops when it should hit a hidden box) or an impossible event (drawbridge rotates 180° through the hidden box as if it did not exist). Infants looked significantly longer at the impossible event — indicating they expected the hidden box to block the drawbridge. This was the foundational demonstration of early object permanence via VOE.
Continuity principle
One of the core physical principles Baillargeon identified in infant cognition: objects move on spatiotemporally continuous paths — they do not teleport, appear or disappear spontaneously, or travel discontinuous trajectories. Infants as young as 2.5 months show surprise when this principle is violated (Wang, Baillargeon & Paterson, 2005). The continuity principle is among the earliest and most robustly documented of infants' physical expectations.
Solidity principle
Infants expect that two distinct solid objects cannot occupy the same space simultaneously. Violations — such as a solid object appearing to pass through another solid object — elicit prolonged looking. The solidity principle is central to understanding the drawbridge paradigm: the impossible event violates the expectation that a solid box prevents a solid drawbridge from rotating through it.
Gravity principle
Infants expect that unsupported objects will fall. Spelke et al. (1992) showed that 6-month-olds look longer when a ball remains suspended after being pushed off a surface without support, compared to a ball that falls. The understanding of gravity and support develops in a coarse-to-fine progression, with early sensitivity to gross violations (floating objects) and later sensitivity to more subtle conditions (partial vs. full support).
Coarse-to-fine developmental progression
Baillargeon's (2004) framework for how physical knowledge develops: infants first appreciate a coarse, categorical version of each physical principle (e.g., "objects don't pass through each other"), then progressively learn which variables modulate this — developing sensitivity to magnitude, configuration, and contextual conditions. This contrasts with Piaget's stage model, which implies uniform absence of understanding before a stage transition.
Core knowledge systems
Spelke & Kinzler's (2007) framework proposing that infants begin life with several domain-specific systems of knowledge — covering objects, agents, number, and geometric space. These systems are characterised as early-emerging, universal across cultures, present in non-human animals, and informationally encapsulated. Baillargeon's findings fit within this framework: object knowledge is not constructed from scratch through sensorimotor experience but reflects an initial, innate representational system that is then elaborated through experience.
Competence–performance distinction
The key theoretical contribution of Baillargeon's research: infants may possess implicit knowledge (revealed by looking behaviour) that they cannot yet express in explicit action (reaching, searching). This undermines stage theories that infer competence solely from successful performance on action tasks. The A-not-B error, on this view, reflects executive and motor limitations, not conceptual absence — younger infants may hold a concept they cannot yet act upon correctly.
Test your knowledge
Sources
Last reviewed July 2025- 1.
Baillargeon, R., Spelke, E. S., & Wasserman, S. (1985). Object permanence in 5-month-old infants. Cognition, 20(3), 191–208. https://doi.org/10.1016/0010-0277(85)90008-3
+About this source
Foundational VOE drawbridge study demonstrating object permanence at 5 months — far earlier than Piaget predicted.
- 2.
Baillargeon, R. (1987). Object permanence in 3.5- and 4.5-month-old infants. Developmental Psychology, 23(5), 655–664. https://doi.org/10.1037/0012-1649.23.5.655
+About this source
Replication and extension of the drawbridge paradigm demonstrating object permanence at 3.5 months.
- 3.
Spelke, E. S., & Kinzler, K. D. (2007). Core knowledge. Developmental Science, 10(1), 89–96. https://doi.org/10.1111/j.1467-7687.2007.00569.x
+About this source
Proposes the core knowledge framework situating Baillargeon's findings within a nativist account of infant cognition.