BAILARGEON’S EXPLANATION OF INFANT ABILITIES
SPECIFICATION: Baillargeon’s explanation of early infant abilities, including knowledge of the physical world, and violation of expectation research.
KEYWORDS
OBJECT PERMANENCE: The understanding that objects continue to exist even when they are no longer visible.
OBJECT PERSISTENCE: Baillargeon’s term for the infant’s early understanding that objects continue to exist and maintain their properties when hidden from view.
VIOLATION OF EXPECTATION (VOE): A research method used in infant studies that measures how long infants look at events. Infants tend to look longer at events that violate their expectations about how the physical world should behave.
LOOKING TIME: A measure used in infant research based on the assumption that infants will look longer at surprising or unexpected events.
POSSIBLE EVENT: An event shown to infants that is consistent with normal physical laws and expectations.
IMPOSSIBLE EVENT: An event that violates physical expectations, such as objects appearing to disappear or pass through barriers.
OCCLUSION: A physical situation in which one object passes behind another object or barrier and becomes temporarily hidden from view.
CONTAINMENT: The understanding that when an object is placed inside a container and the container is closed, the object remains inside even when it is no longer visible.
SUPPORT: The principle that objects remain stable only when supported by a surface and will fall if unsupported.
PHYSICAL REASONING SYSTEM (PRS): Baillargeon’s proposed innate cognitive system that directs infants’ attention to events that violate their expectations about the physical world.
EVENT CATEGORIES: Types of interactions between objects, such as containment, support, occlusion, or collision, that infants gradually learn to understand through experience.
INFANT COGNITION: The study of how infants think, learn, and understand the world during the earliest stages of development.
IMPLICIT KNOWLEDGE: Knowledge that infants possess but cannot yet demonstrate through deliberate actions, such as searching or manipulating objects
RENÉE BAILLARGEON (1949 – )QUICK BIOGRAPHY
Renée Baillargeon is a developmental psychologist whose research focuses on infant cognition, particularly how infants understand the physical properties of the world. She completed her undergraduate studies at McGill University in Canada and later received her PhD in cognitive psychology from the University of Pennsylvania in 1981. She subsequently became a professor of psychology at the University of Illinois at Urbana-Champaign, where much of her influential research on infant reasoning has been conducted.
Baillargeon began her research during a period when Jean Piaget’s theory of cognitive development dominated developmental psychology. Piaget had argued that infants gradually develop knowledge about the physical world through active interaction with objects. According to Piaget, the concept of object permanence does not fully emerge until around eight months of age, when infants begin to actively search for hidden objects.
Baillargeon began questioning Piaget’s conclusions while working in the field of infant cognitive development, where researchers sought to understand what very young infants actually know about the physical world. During the late 1970s and early 1980s, many developmental psychologists re-examined Piaget’s claims using new experimental methods that did not require infants to physically manipulate objects.
Piaget’s conclusions about object permanence were largely based on search tasks. In these tasks, an object was hidden, and the infant’s understanding was inferred from whether the child attempted to retrieve it. If the infant failed to search, Piaget interpreted this as evidence that the infant believed the object had ceased to exist. Baillargeon and other researchers began to question whether these tasks were actually measuring cognitive understanding or were confounded by other factors, such as motor limitations, attention span, and motivation. Young infants may understand that an object continues to exist but still fail to retrieve it because they lack the physical ability to coordinate the necessary actions.
VIOLATION OF EXPECTATION RESEARCH
This question led Baillargeon to investigate whether infants might show evidence of implicit understanding of physical events even when they are unable to act on that knowledge. Her research, therefore, focused on developing methods to reveal infants’ expectations about the physical world without relying on complex motor responses. This work ultimately led to the development of the violation-of-expectation paradigm, which became a central method in modern infant cognition research.
To overcome this limitation, Baillargeon introduced the violation-of-expectation (VOE) paradigm, a method that measures infants’ looking time rather than their physical actions. The logic behind this method is that infants develop expectations about how objects should behave. When an event contradicts those expectations, infants typically look at it for longer, indicating surprise. This reaction suggests that the infant possesses some prior understanding of the physical event being shown.
Baillargeon et al. (1985) applied this method to investigate object permanence in infants aged five to six months. In the experiment, infants watched a rabbit move behind a screen that contained a window. In the event of a short rabbit disappearing behind the screen and not appearing in the window, whereas a tall rabbit passed behind the screen and was visible through the window. This outcome was physically consistent because the tall rabbit was higher than the window opening.
In the impossible event, however, neither rabbit appeared in the window. This outcome violated the laws of physical reality because the tall rabbit should have been visible if it continued along its path behind the screen. Infants looked significantly longer at this impossible event, on average, about eight seconds longer than the possible one. Baillargeon interpreted this as evidence that the infants expected the tall rabbit to remain visible. The longer looking time, therefore, suggested that the infants believed the rabbit continued to exist behind the screen and had mentally represented its height even when it was hidden.
On the basis of these findings, Baillargeon concluded that infants possess an early form of object persistence by approximately five months of age, considerably earlier than Piaget had suggested.
INFANT KNOWLEDGE AND REASONING ABOUT THE PHYSICAL WORLD ACCORDING TO BAILLARGEON
Baillargeon’s account of infant knowledge about the physical world represents a nativist explanation of early cognitive abilities.
She proposed that infants possess an inborn understanding of object permanence, in contrast to Piaget, who argued that object permanence develops gradually and only emerges at around eight months of age.
According to Baillargeon, infants are not required to construct their understanding of the physical world slowly through experience. Instead, she suggested that infants are born with a pre-existing framework for interpreting physical events.
Baillargeon later referred to this underlying mechanism as the physical reasoning system (PRS) (Baillargeon, 2012).
Within this framework, infants are assumed to possess an early understanding of object persistence, meaning that objects continue to exist even when they are occluded. To investigate this idea, Baillargeon developed a series of experimental studies designed to test whether infants show expectations about how objects should behave in the physical world
VIOLATION OF EXPECTATION IN SUMMARY
Violation of expectation (VOE) refers to events which defy logic and do not appear to be physically possible
VOE research depends upon an infant’s innate understanding of the physical world
E.g. If a dog walks behind a fence, I can’t see the dog anymore
Baillargeon researched VOE by setting up a series of experiments in which an infant’s reaction to an impossible event was observed
An impossible event is one which should not happen if objects/people/animals obey the laws of physics, i.e., solid objects should not be visible if they are obscured by another solid object
BAILLARGEON ET AL. (1985): VIOLATION OF EXPECTATION STUDY
AIM: The aim of Baillargeon et al.’s research was to investigate whether infants possess an early understanding of object permanence, or what Baillargeon later described as object persistence. The study examined whether infants expect objects to continue to exist and maintain their physical properties when temporarily hidden through occlusion.
DESIGN: The study used a controlled laboratory experiment based on the violation-of-expectation (VOE) paradigm. This design compared infants’ looking times when they observed two different events: a possible event that followed normal physical principles and an impossible event that violated those expectations.
PARTICIPANTS: The sample consisted of 24 infants aged between five and six months. As is typical of early infant cognition research conducted in American university laboratories, participants were recruited through volunteer samples, often responding to advertisements or identified through local birth records. The infants were typically from middle-class American families, most commonly with White mothers, reflecting the demographic composition of families who volunteer for developmental research in university settings.
This sampling pattern may mean that the participants are not representative of infants from other cultural or socioeconomic backgrounds. Cross-cultural research in development has shown that aspects of infant development can vary depending on environmental conditions. For example, studies of infants in parts of Uganda have reported earlier development of behaviours such as object permanence and stranger anxiety, partly because infants in those cultures often develop motor skills such as walking earlier, as caregiving practices encourage greater physical activity. Such findings suggest that cultural experiences may influence the timing of developmental milestones.
METHOD / PROCEDURE: Infants were seated facing a small stage apparatus, with a screen with a window placed between the infant and a moving object. The moving object was a rabbit that travelled horizontally behind the screen. When the rabbit moved behind the screen, it became temporarily occluded.
Two types of events were presented.
In the event of a short rabbit moving behind the screen and not appearing in the window, a tall rabbit moved behind the screen and could be seen through the window opening. This outcome was physically possible because the tall rabbit was higher than the window.
In the impossible event, neither rabbit appeared in the window as it moved behind the screen. This outcome violated expectations about object persistence, because the tall rabbit should have remained visible if it continued along its path behind the barrier.
The infants’ looking time was recorded in both conditions.
RESULTS: Infants looked significantly longer at the impossible event than at the possible event. On average, infants looked approximately 7.96 seconds longer at the impossible condition.. Within the logic of the violation-of-expectation paradigm, this longer looking time indicates that infants detected a violation of their expectations about how objects behave.
CONCLUSION: Baillargeon concluded that the infants represented the hidden rabbit and its physical properties, such as its height, even when it was no longer visible. This suggests that infants expected the tall rabbit to appear in the window as it moved behind the screen.
The findings, therefore, indicate that infants as young as five months possess an early understanding of object persistence, challenging Piaget’s claim that object permanence does not emerge until around eight months of age. Baillargeon later proposed that this early understanding reflects the operation of a developing physical reasoning system (PRS) that helps infants interpret interactions between objects and build knowledge of different event categories, including occlusion, containment, and support.
OTHER RESEARCH INVESTIGATING BAILLARGEON’S THEORY
Several studies have examined the idea that infants possess early knowledge of the physical world and expectations about how objects behave.
Bower (1982) conducted an experiment in which infants were shown both possible and impossible events while their heart rate was measured. The results showed that infants’ heart rates increased when they observed the impossible event. This physiological response suggests that infants detected something unexpected about the event, supporting the idea that they possess early expectations about how objects should behave.
Further evidence comes from Wang et al. (2003), who conducted two experiments examining whether very young infants demonstrate a violation-of-expectation (VOE) effect when observing hidden objects. Their findings showed that four-month-old infants displayed VOE responses even without the usual habituation phase often used in infant studies. This suggests that infants may already have expectations about object behaviour without requiring extensive prior exposure to the event.
Aguilar and Baillargeon (1999) also tested infants’ expectations about object persistence using a VOE procedure. Infants were first habituated to seeing a Minnie Mouse toy move from one side of a screen to the other. Two conditions were then presented. In the high-window condition, which represented a possible event, the toy passed behind the screen and was visible through the high window. In the low window condition, which represented an impossible event, the toy passed behind the screen but could not appear in the lower window. As predicted by the VOE method, infants looked significantly longer at the low window condition, suggesting that they detected the violation of their expectations about how the object should behave when it moved behind the screen
EVALUATION OF BAILLARGEON’S VIOLATION OF EXPECTATION RESEARCH
SUPPORT FOR EARLY OBJECT KNOWLEDGE
One strength of Baillargeon’s research is that it provides evidence that infants may possess knowledge about the physical world earlier than Piaget suggested. The violation-of-expectation method measures infants’ looking time, allowing researchers to investigate infants’ expectations about events even when they are too young to demonstrate their understanding through physical actions. When infants look significantly longer at an impossible event, it suggests that the event violates their expectations. This indicates that infants may be reasoning about hidden objects and their properties during occlusion, suggesting an early form of object knowledge.
Importantly, this pattern has been replicated across numerous violation-of-expectation studies examining different aspects of the physical world. Researchers have found similar results when investigating principles such as solidity, where objects cannot pass through one another, support, where objects require adequate support to remain stable, and containment, where objects must remain within the boundaries of a container unless acted upon. In these studies, infants consistently look longer at events that appear to violate these principles, suggesting that they detect inconsistencies in how objects behave.
Evidence suggesting that the PRS is universal = There are examples of infantile understanding which are innate (e.g. sucking and gripping), whilst a basic physical understanding of the world can be developed through experience. For example, many infants will recognise that if you play a toy on a table, it will stay there, but if you let a toy fall to the ground, it will do so. This suggests that some aspects of the PRS must be universal. This was further supported by Hespos and van Marle (2012), who concluded that “certain core principles about these domains [solidity, continuity, cohesion, and 5 property changes] are present as early as we can test for them and the nature of the underlying representation is best characterised as primitive initial concepts that are elaborated and refined through learning and experience”.
The replication of these findings across different physical scenarios strengthens the argument that infants possess early expectations about the behaviour of objects. Rather than reflecting a response to a single experimental display, the consistency of longer looking times across multiple studies and physical principles suggests that infants may possess a broader early sensitivity to the regularities of the physical world.
MUNDANE REALISM OF LABORATORY TASKS
Another limitation concerns the mundane realism of violation-of-expectation experiments. Baillargeon’s studies typically use highly controlled laboratory displays, such as rotating screens, hidden boxes, and simplified occlusion events. While this level of control allows researchers to isolate specific physical principles, it also means that the situations presented to infants are artificial compared with the complex object interactions they encounter in everyday life.
In natural environments, infants experience objects through active exploration, including touching, manipulating, and observing objects in dynamic social contexts. By contrast, violation-of-expectation studies often involve infants passively observing simplified visual events on a stage or screen. Because these displays are designed to highlight specific physical violations, they may capture infants’ attention in ways that differ from ordinary experiences with objects.
VALIDITY OF THE VIOLATION OF EXPECTATION MEASURE
Another limitation concerns the interpretation of looking time as evidence of infants’ understanding. In violation-of-expectation studies, longer looking at an impossible event is interpreted as a sign that the infant is surprised because the event violates an expectation about how objects behave. However, this interpretation depends on assumptions about what looking behaviour represents. Because infants cannot verbally explain their responses, researchers must operationalise cognitive processes such as surprise or expectation using indirect behavioural measures such as gaze duration. This creates a construct validity problem because it is difficult to determine whether the measure genuinely reflects the psychological process it is intended to represent.
For example, infants may look longer at an impossible event simply because it is visually unusual or perceptually interesting rather than because it violates a cognitive expectation. Displays involving unexpected movement or changes in the visual scene may capture attention more strongly than predictable events. If this is the case, a longer looking time may reflect perceptual novelty rather than reasoning about hidden objects.
Distinction drawn between behavioural response and behavioural understanding = Bremner drew this distinction, emphasising that the two are not the same. For example, just because an infant looks at an impossible condition for longer does not necessarily mean they understand the differences in height and appearance between the objects, and thus cannot consciously reason about it. This means that Baillargeon may have overestimated the significance of her results and so reached potentially incorrect causal conclusions. — Causal Conclusions = Particularly with such young infants (as used in the VOE research), it is difficult to judge what they actually understand. There may be many reasons why one infant finds a certain scene more interesting than another, and this may not necessarily be due to a violation of their expectations. The second criticism is that we are assuming their expectations have been broken and that they are ‘surprised’ by the impossible condition. However, we cannot be sure that they even experience expectations about the physical world in the first instance
Some research supports this concern. Rivera et al. (1999) suggested that infants may look longer at impossible events not because they detect a violation of physical principles but because such events contain more dynamic or visually distinctive stimuli. If infants prefer watching unusual or moving displays, then the longer looking observed in Baillargeon’s studies may reflect perceptual preferences rather than genuine understanding of object permanence.
A further difficulty arises from the nature of infant participants. Because infants cannot report their thoughts or intentions, researchers must infer their cognitive states from indirect indicators such as gaze direction, looking time, or physiological responses. This means that the same behavioural response may have multiple possible explanations. Consequently, although violation of expectation studies provide valuable insights into infant cognition, conclusions about early object knowledge must be interpreted cautiously because the underlying mental processes cannot be measured directly
As a result, infants’ longer looking times in laboratory settings may reflect responses to unusual visual displays rather than the same type of understanding that operates during real-world interactions with objects. Although the controlled design of violation-of-expectation experiments is useful for isolating specific variables, the artificial nature of the tasks means that conclusions about infants’ everyday understanding of the physical world should be interpreted with caution.
COUNTER ARGUMENT
However, some researchers argue that these findings may still reflect perceptual sensitivity rather than genuine conceptual understanding. Piaget maintained that behaviour which appears consistent with a rule does not necessarily demonstrate that the rule is understood. Infants may react to an unusual visual event without possessing knowledge of the physical principle behind it.
In violation-of-expectation studies, infants often look longer at events that appear impossible, such as an object passing through a solid barrier. Baillargeon interpreted this longer-looking time as evidence that infants understand principles such as object permanence and solidity. Critics argue that this conclusion may be premature.
Piaget’s position was that true cognitive understanding is demonstrated through action, not simply through visual attention. A child who genuinely understands that objects continue to exist when hidden should be able to search for the object or manipulate the environment accordingly. In contrast, looking behaviour may simply reflect surprise or perceptual novelty.
Therefore, infants’ longer looking times may indicate that they detect unusual patterns in visual displays rather than that they understand the physical rules governing objects. From this perspective, violation of expectation findings may demonstrate early perceptual awareness, but not necessarily a fully developed conceptual understanding of the physical world
DEVELOPMENTAL CONTINUITY
Another issue concerns whether early perceptual sensitivity necessarily reflects the same type of understanding seen later in development. Violation-of-expectation studies demonstrate that infants can detect when an event appears unusual or inconsistent with prior experience. However, recognising that something is unexpected does not necessarily mean that infants possess a fully developed concept of how objects behave. Detecting a violation may reflect perceptual sensitivity to changes in visual patterns rather than a mature conceptual understanding of physical principles such as object permanence.
From this perspective, early responses to expectation-violation tasks may reflect rudimentary sensitivity to physical regularities rather than the same type of conceptual knowledge that older children demonstrate when they can deliberately reason about objects. Later in development, children can apply their knowledge flexibly across different situations, predict outcomes, and explain why events occur. Infants’ longer looking times do not necessarily demonstrate this level of conceptual understanding.
This raises the possibility that early perceptual expectations and later conceptual knowledge may represent different stages in the development of understanding about the physical world. Detecting violations of expectation may therefore reflect an early precursor to object knowledge rather than evidence that infants already possess the same conceptual understanding observed in older children
CULTURAL RELEVANCE
One limitation concerns the cultural relevance of Baillargeon’s findings. Most violation-of-expectation studies have been conducted with infants from Western, middle-class families, yet early development can be influenced by differences in caregiving practices and everyday environments across cultures. Although the physical principles being studied, such as object persistence or solidity, are universal, the timing and behavioural expression of infants’ understanding may vary depending on experience.
Research in developmental psychology has shown that developmental milestones can occur at different ages in different cultural contexts. For example, studies of infants in parts of Uganda have reported earlier emergence of behaviours such as stranger anxiety and aspects of object-related awareness. One explanation is that infants in these environments often develop motor abilities such as sitting, crawling, and walking earlier due to patterns of physical interaction and handling by caregivers. Earlier mobility changes the infant’s visual and spatial experience of the world. A child who begins moving independently sooner encounters more situations in which objects appear, disappear, or move behind barriers, which may provide earlier opportunities to learn about the persistence and behaviour of objects.
Caregiving environments may also affect how infants attend to objects. In some cultures, infants spend more time physically attached to caregivers or carried on the body, while in others, they spend more time on the ground exploring the environment independently. Differences in physical positioning, levels of movement, and opportunities for exploration can alter the kinds of perceptual experiences infants have with objects. An infant who regularly observes objects from different vantage points while moving around may encounter occlusion events more frequently than an infant whose environment is more visually stable.
However, it is important to note that there has been relatively little direct cross-cultural replication of Baillargeon-style violation-of-expectation experiments. Most studies using this paradigm have been conducted in Western laboratory settings. This means that while the basic physical principles of the environment are the same across cultures, it is less clear whether the age at which infants demonstrate these expectations, or the specific behavioural patterns used to infer them, would appear in exactly the same way across different cultural contexts. Consequently, although Baillargeon’s theory may describe a universal aspect of early cognition, the limited cultural diversity of the research samples means that conclusions about the timing and expression of this knowledge should be interpreted cautiously
Are babies capable of understanding Baillargeon’s experiments? The tasks used in these studies are cognitively quite sophisticated. The train experiment assumes that infants as young as about five months old understand that a solid object cannot pass through another solid object. In the study, infants watched a toy train move behind a screen where a block was hidden. When the train appeared to pass straight through the block, infants looked longer, which Baillargeon interpreted as evidence that they understood the event was impossible. However, this interpretation assumes that infants of this age already possess a concept of object solidity and physical obstruction, which is a strong cognitive assumption.
WERE BAILLGOEN’S TASKS TOO DIFFICULT FOR BABIES?
A similar issue appears in Baillargeon’s window experiment, conducted with infants at about 3.5 months. In this task, a screen with a window rotated back and forth. A tall object, such as a rabbit or a carrot, was placed behind the screen. In the impossible condition, the screen appeared to rotate fully despite the object being taller than the window. Infants looked longer at this event, which Baillargeon argued shows that even very young babies understand that an object that is taller than the window cannot disappear behind it. Critics argue that such tasks may place demands on perceptual processing that infants may not fully comprehend.
Evidence from the visual cliff experiment suggests a different picture of early understanding. Research by Gibson and Walk (1960) showed that infants around six to ten months of age, particularly once they begin crawling, start to show clear avoidance of the apparent drop. This suggests that depth perception develops alongside locomotor experience. In other words, babies may need the experience of moving through the environment before they properly understand depth.
Further research also shows that infants can override their perceptual hesitation in response to social cues. In a well-known study by Sorce, Emde, Campos and Klinnert (1985), infants were placed on the visual cliff while their mothers displayed either a happy or fearful facial expression. When mothers smiled and encouraged them, many infants crossed the apparent drop. When mothers showed fear, infants refused to cross. This violates their own perception of depth, as infants initially hesitate at the edge until their mother provides incongruent non-verbal cues, demonstrating that social signals can override their perceptual judgement.
CONGENITAL BLINDNESS AND DEPTH PERCEPTION
Similarly, evidence from individuals who regain sight after early visual deprivation also highlights the importance of experience in perceptual development. For example, Project Prakash, conducted by Pawan Sinha, studied children in India who were born with congenital cataracts and regained sight after surgery. Even after their vision was restored, many initially struggled with face, object, and depth perception. These abilities improved only gradually with visual experience.
This suggests that experience-dependent plasticity operates within critical periods, during which the brain expects specific sensory input to develop normally. If that input is absent during early development, some perceptual abilities do not emerge automatically once vision is restored.
This evidence, therefore, raises a similar issue for Baillargeon’s interpretation of infant cognition. If fundamental perceptual abilities such as depth perception and object recognition depend on visual experience, it is questionable whether very young infants already possess the sophisticated physical reasoning that Baillargeon’s experiments appear to assume.
THEORETICAL DIFFERENCES BETWEEN PIAGET AND BAILLARGEON
A further evaluative issue concerns the theoretical interpretation of infants’ abilities. Baillargeon’s work is often presented as challenging Piaget’s account of early cognitive development. Piaget argued that knowledge of the physical world emerges gradually during the sensorimotor stage as infants actively interact with objects. In his view, concepts such as object permanence develop through action-based exploration, including reaching, grasping, searching, and manipulating objects.
Baillargeon, by contrast, interpreted infants’ longer looking at impossible events as evidence that some knowledge of physical principles may already be present very early in development. Her interpretation, therefore, assumes that infants possess cognitive expectations about objects even before they can demonstrate this knowledge through coordinated physical actions.
However, this raises an important theoretical question about the relationship between cognitive development and physical experience. Baillargeon’s interpretation assumes that cognitive understanding may precede the motor ability to express it. In other words, infants may already possess expectations about the behaviour of objects but lack the physical coordination required to demonstrate that knowledge in Piaget’s search tasks.
An alternative interpretation is that physical development itself contributes to cognitive development. Many aspects of early learning about the physical world are closely tied to changes in motor ability. As infants progress from lying down to sitting, crawling, and eventually walking, they encounter objects from new spatial perspectives and gain increasing opportunities to observe how objects move, disappear, and reappear in the environment. These changing vantage points can fundamentally alter how infants perceive and understand spatial relationships. For example, a crawling or walking infant experiences occlusion events far more frequently than a stationary infant, potentially accelerating understanding of object persistence.
From this perspective, cognitive development may not simply precede physical ability. Instead, physical development may actively facilitate the emergence of cognitive understanding. Motor development provides new forms of interaction with the environment, which in turn generate the experiences from which infants construct knowledge about objects and space.
Importantly, this suggests that the debate between Piaget and Baillargeon may not represent a fundamental theoretical disagreement. Both researchers assume that development involves biological maturation interacting with environmental experience. Piaget emphasised the role of action and sensorimotor exploration in constructing knowledge, whereas Baillargeon proposed that infants possess earlier expectations about the physical world than Piaget believed. In this sense, the disagreement may concern the timing and interpretation of early abilities rather than a completely different theoretical framework.
Both perspectives, therefore, accept that infants’ understanding of the physical world emerges through an interaction between biological development and environmental experience. The main difference lies in whether this knowledge appears later through active exploration, as Piaget proposed, or whether rudimentary expectations may already be present earlier in infancy, as Baillargeon’s findings suggest
ISSUES AND DEBATES
Baillargeon’s theory reflects a nativist position in the nature-versus-nurture debate. By proposing that infants possess an innate Physical Reasoning System (PRS), she suggests that some aspects of cognitive development are biologically prepared rather than constructed entirely through experience. According to this view, infants are born with core expectations about how objects behave, such as principles of solidity, persistence, and support. This places Baillargeon’s explanation on the nature side of the debate, implying that basic knowledge of the physical world emerges very early in development rather than being gradually built through learning and interaction with the environment.
However, critics argue that early cognitive abilities may still depend heavily on experience. Even very young infants are exposed to repeated physical events in which objects appear, disappear, collide, or fall. Through observing these regularities, infants may rapidly develop expectations about object behaviour without requiring an innate reasoning system. This interpretation, therefore, places greater emphasis on nurture and the role of environmental experience in shaping early cognitive development.
BAILLARGEON APPLIED
CHILDREN UNDERSTANDING PHYSICAL PROPERTIES
Baillargeon proposed that even very young infants possess a basic awareness of how objects behave. Imagine a nursery worker named Tina who accidentally drops her keys behind a desk. Instead of falling to the floor with a loud noise, the keys land quietly in an open drawer. Several children who witnessed the event stare at the drawer with great interest, which surprises Tina. She wonders why the children appear so fascinated by what happened.
QUESTIONS
Baillargeon studied early infant abilities by conducting violation-of-expectation studies. What is meant by ’violation of expectation’? (Total 1 mark)
Describe the concept of violation of expectation. (3 marks
Outline Baillargeon’s explanation of infant abilities, including knowledge of the physical world. (4 marks)
Describe one study of the violation of expectation. In your answer, include details of the procedure and findings. (6 marks)
Describe one way in which psychologists have investigated the cognitive abilities of infants under the age of two years. Refer to a specific study in your answer. (6 Marks)
Evaluate the way of investigating infant cognitive abilities that you have described in your answer to part. Do not refer to ethical issues in your answer. (Total 6 marks)
Describe and evaluate Baillargeon’s explanation of early infant abilities (10 marks)
Discuss what Baillargeon’s research has told us about early infant abilities. (Total 16 marks)
ESSAY EXEMPLAR
BAILLARGEON’S EXPLANATION OF EARLY INFANT ABILITIES
Piaget’s account of object permanence: Piaget (1954) claims that infants do not conceive of objects as having an independent existence, separate from themselves. In the infant’s world, objects pop in and out of existence as they impinge on the child’s senses or cease to do so. Before about eight or nine months, an infant will not search for a toy that is hidden under a cloth in front of it. Piaget took the child’s failure to search to mean that once the object was out of sight, it was also out of the child’s mind, since the child did not understand that the toy continued to exist whilst hidden. Around nine months, the child will begin to search for the hidden object. However, it does not have a full understanding of objects' independent existence. If a toy is hidden in one place, and then immediately moved in the child’s view to another hiding place, the child will still search for it in the first location where the object was hidden (this is called the ‘A not B error’). Piaget thought that this represented a transitional phase in the child’s understanding. The child has the notion that the object still exists whilst hidden, but believes that its own actions determine where the toy will be uncovered, as if the act of searching ‘calls the object back into existence’. The child’s belief that its own perceptions and actions are the centre of everything is a manifestation of what Piaget called egocentrism. It is not until the child is about eighteen months old that it reliably searches for an object in the correct location.
Challenges to Piaget’s account. A number of researchers have pointed out that Piaget’s search tasks may not be a valid test of infants’ object permanence. The problem is that failure to search might indicate a number of things besides the lack of an object concept: that the child has been distracted, lost interest, or can’t coordinate its muscular movements to carry out the search. Piaget assumed that an infant’s failure to perform (carry out the search) indicates a lack of competence (an understanding of object permanence). This may have led him to underestimate children’s abilities. By analogy, if you were introduced to a five-year-old child who did not talk (i.e., did not produce speech), you probably would not immediately assume that the child was unable to talk (i.e., lacked the competence to speak). More likely, you would assume that something was preventing the child from displaying its competence at speaking (shyness, for example). But Piaget seems to be making just such an error: when the child does not search, Piaget concludes that it lacks the underlying capacity to do so. If it is true that Piaget’s search task does not measure an infant’s competence, it follows that a task more in tune with what an infant can do well might be able to detect signs of object permanence at a younger age than the eight or nine months claimed by Piaget.
Bower et al. (1971) designed a task that assessed a skill infants acquire much younger than eight months: the ability to direct where they look. Infants can follow (track) a moving object with their eyes. In Bower et al’s study, four-month-old infants were shown a train moving along a track. The train went behind a screen that blocked the infant’s view. A researcher carefully observed where the infants looked. According to Piaget, as soon as the train was no longer visible, the infants should lose interest and look elsewhere, since for them the train no longer exists. Bower et al. found, however, that the infants would direct their gaze to the other side of the screen, where the train was expected to emerge. This implies an understanding that the train still exists even though the infant cannot see it. In follow-up studies, things were arranged so that instead of the train, a different object emerged from the other side of the screen. When this happened, some of the infants showed signs of surprise, suggesting again that they expected the train to emerge. All this was recorded with four-month-old children, suggesting that Piaget did indeed underestimate the age at which children develop object permanence.
Baillargeon’s violation of expectation studies. A further challenge to Piaget’s claims comes from a series of studies designed by Renee Baillargeon. She used a technique known as the violation-of-expectation (VOE) paradigm. It exploits the fact that infants tend to look for longer at things they have not encountered before. In a VOE experiment, an infant is first introduced to a novel situation. They are repeatedly shown this stimulus until they indicate, by looking away, that it is no longer new to them. In Baillargeon et al’s (1985) study, the habituation stimulus was a ‘drawbridge’ that moved through 180 degrees. The infants are then shown two new stimuli, each a variation of the habituation stimulus. In Baillargeon’s experiments, one of these test stimuli is a possible event (i.e. one which could physically happen), and the other is an impossible event (i.e. one that could not physically happen in the way it appears). In the ‘drawbridge’ study, a coloured box was placed in the path of the drawbridge. In the possible event, the drawbridge stopped at the point where its path would be blocked by the box. In the impossible event that the drawbridge appeared to pass through the box and ended up lying flat, the box apparently had disappeared. Baillargeon found that infants spent much longer looking at the impossible event. She concluded that this indicated surprise on the infants’ part and that the infants were surprised because they had expectations about the behaviour of physical objects that the impossible event had violated. In other words, the infants knew that the box still existed behind the drawbridge and, furthermore, that one solid object cannot just pass through another. The infants in this study were five months old, an age at which Piaget would say that such knowledge is quite beyond them.
In a similar study, Baillargeon (1987) habituated 3-month-old infants to a truck rolling down a track, with the truck behind a screen. The screen was removed. A box was introduced and placed either beside the track where the truck would roll past it or on the track where it should block the truck’s path. The screen was then replaced and the truck sent down the track as before. In both events, the truck passed behind the screen unimpeded. This would be impossible where the box had been placed so as to block the track. Baillargeon found, once again, that infants looked significantly longer at this impossible event and concluded that they knew the box still existed despite being behind the screen and that it should have blocked the truck's path. Her studies therefore seem to indicate that three-month-old infants have an understanding of objects that Piaget says does not appear until nine to twelve months.
The ‘core knowledge’ theory in Piaget’s theory, infants acquire their knowledge of objects by interacting with the world around them. It is through interacting with objects that the child gradually realises that things have an independent existence of their own, that they occupy space, and that they persist in time. This takes time for the child to work out, which is why object permanence is only present after about nine months. But Baillargeon’s results seem to show that object knowledge is present from a much earlier age, one at which infants have very limited experience of interacting with objects. So where does their knowledge of objects come from?
Baillargeon (1987) suggested two possibilities. Either infants are born with the capacity to acquire object knowledge very easily (innate fast learning), or they are born with an understanding of the properties of objects (innate object knowledge). The latter hypothesis was developed by Spelke et al (1992), who argue that infants are born with what they call core knowledge. This core knowledge includes a basic understanding of the physical world, including the properties of objects such as: • Solidity of objects: each object occupies space; objects cannot pass through each other. • Continuity of motion: objects move in paths through space; an object can only get from A to B by moving on a continuous path that starts at A and ends at B. At birth, these rules are rather primitive. As the child develops, they become more sophisticated and interconnected. Baillargeon (2002) suggests that the child’s understanding develops through experiences that challenge its primitive ideas, which is consistent with Piaget. However, her and Spelke’s theory that infants are born with some understanding of the world conflicts fundamentally with Piaget’s theory that the child’s understanding comes entirely from its own experiences.
EVALUATION
Whilst Piaget takes an empiricist or interactionist position, Baillargeon and Spelke are nativists. Criticisms of Baillargeon’s research. Many studies have used Baillargeon’s methodology, and they consistently produce similar results. As a consequence, the core knowledge theory is widely accepted amongst developmental psychologists. However, there are those who object to Baillargeon’s and Spelke’s interpretation of the VOE findings. Their criticism is that Baillargeon has gone far beyond what the data actually show. She says that when infants look for longer at the impossible events, this is because they are surprised, as their expectations have been violated. Schoner and Thelen (2004) point out that all the VOE studies definitely show is that the infants notice a difference between the two events they have been shown. Everything else is an extrapolation from this. Schoner and Thelen argue that there are many reasons infants might prefer to look at the ‘impossible’ events. For example, in the ‘drawbridge’ study, the ‘impossible’ event involves more movement than the ‘possible’ event. They conclude that Baillargeon has mistakenly assumed that the only difference between her stimuli is that one is ‘possible and the other is ‘impossible’. However, there are many differences between the two stimuli, any of which might explain why infants look more at one than the other. What Baillargeon and Spelke claim is evidence of innate knowledge of the physical world, Schoner and Thelen say, is no more than the effect of confounding variables.
CRITICISMS
Baillargeon's research on object permanence met criticism from Gregor Schoner and Esther Thelen. Schoner and Thelen argued that Baillargeon was overly extrapolating the results of her studies on infants' knowledge regarding object permanence.[10] They believe that the violation-of-expectation paradigm merely indicates that infants notice a difference between stimuli, such as more movement or different colours, rather than showing surprise at the sight of a seemingly impossible event.[10] Despite these criticisms, Baillargeon's work continues to be influential in developmental psychology.
REFERENCES
Baillargeon, R. (1987). Object Permanence in 3 ½ and 4 ½ Month Old Infants. Developmental Psychology, 23, 655-664. Baillargeon, R. (2002). The Acquisition of Physical Knowledge in Infancy: A Summary in Eight Lessons. In U.Goswami (Ed.) “Blackwell Handbook of Childhood Cognitive Development”. Oxford, Blackwell. Baillargeon, R., Spelke, E.S. & Wasserman, S. (1985). Object Permanence in Five-Month-Old Infants. Cognition, 20, 191-208. Piaget, J. (1954). The Construction of Reality in the Child. New York NY, Basic Books. Schöner, G. & Thelen, E. (2006). Using Dynamic Field Theory to Rethink Infant Habituation. Psychological Review, 113, 273-299. Spelke, E.S., Breinlinger, K., Macomber, J. & Jacobson, K. (1992). Origins of Knowledge. Psychological Review, 99, 605-632. Research
