Young infants' actions reveal their developing knowledge of support variables: converging evidence for violation-of-expectation findings

"Dividing the labor": Lexical verbs and the linguistic encoding of physical support in 2- to 4.5-year-old children

Infants reason about support configurations (e.g., teddy bear on table) and young children talk about a variety of support relations, including support-from-below (e.g., apple on table) and many other types (e.g., Band-Aid on leg, picture on wall). Given this wide variation in support types, we asked whether early differentiation of the semantic space of support may play a key role in helping children to learn spatial language in this domain. Previous research has shown such differentiation with 20-month-olds mapping the basic locative construction (BE on) to support-from-below (cube on top of box), but not to a mechanical support configuration (cube on side of box via adhesion). Older children and adults show the same differentiation, with preferential mapping of BE on to support-from-below and lexical verbs to mechanical support. We further explored the development of this differentiation by testing how children aged 2 to 4.5 years map lexical verbs to a wide variety of support configurations. In Experiment 1, using an intermodal preferential pointing paradigm, we found that 2- to 3.5-year-olds map a lexical verb phrase ("sticks to") to mechanical support via adhesion. In Experiments 2 and 3, we expanded the range of mechanical support relations and used production and forced-choice tasks to ask whether 2- to 4.5-year-olds also encode mechanical relations using lexical verbs. We found that they do. These findings suggest continuity between infancy and childhood in the way that children use spatial language to differentially map to support-from-below versus mechanical support and raise new questions about how mechanical support language develops.

The privileging of 'Support-From-Below' in early spatial language acquisition

Spatial terms that encode support (e.g., "on", in English) are among the first to be understood by children across languages (e.g., Bloom, 1973; Johnston & Slobin, 1979). Such terms apply to a wide variety of support configurations, including Support-From-Below (SFB; cup on table) and Mechanical Support, such as stamps on envelopes, coats on hooks, etc. Research has yet to delineate infants' semantic space for the term "on" when considering its full range of usage. Do infants initially map "on" to a very broad, highly abstract category - one including cups on tables, stamps on envelopes, etc.? Or do infants begin with a much more restricted interpretation - mapping "on" to certain configurations over others? Much infant cognition research suggests that SFB is an event category that infants learn about early - by five months of age (Baillargeon & DeJong, 2017) - raising the possibility that they may also begin by interpreting the word "on" as referring to configurations like cups on tables, rather than stamps on envelopes. Further, studies examining language production suggests that children and adults map the basic locative expression (BE on, in English) to SFB over Mechanical Support (Landau et al., 2016). We tested the hypothesis that this 'privileging' of SFB in early infant cognition and child and adult language also characterizes infants' language comprehension. Using the Intermodal-Preferential-Looking-Paradigm in combination with infant eye-tracking, 20-month-olds were presented with two support configurations: SFB and Mechanical, Support-Via-Adhesion (henceforth, SVA). Infants preferentially mapped "is on" to SFB (rather than SVA) suggesting that infants differentiate between two quite different kinds of support configurations when mapping spatial language to these two configurations and more so, that SFB is privileged in early language understanding of the English spatial term "on".

Five-month-old infants attribute inferences based on general knowledge to agents

To make sense of others' actions, we generally consider what information is available to them. This information may come from different sources, including perception and inference. Like adults, young infants track what information agents can obtain through perception: If an agent directly observes an event, for example, young infants expect the agent to have information about it. However, no investigation has yet examined whether young infants also track what information agents can obtain through inference, by bringing to bear relevant general knowledge. Building on the finding that by 4 months of age most infants have acquired the physical rule that wide objects can fit into wide containers but not narrow containers, we asked whether 5-month-olds would expect an agent who was searching for a wide toy hidden in her absence to reach for a wide box as opposed to a narrow box. Infants looked significantly longer when the agent selected the narrow box, suggesting that they expected her (a) to share the physical knowledge that wide objects can fit only into wide containers and (b) to infer that the wide toy must be hidden in the wide box. Three additional conditions supported this interpretation. Together, these results cast doubt on two-system accounts of early psychological reasoning, which claim that infants' early-developing system is too inflexible and encapsulated to integrate inputs from other cognitive processes, such as physical reasoning. Instead, the results support one-system accounts and provide new evidence that young infants' burgeoning psychological-reasoning system is qualitatively similar to that of older children and adults.

How do the object-file and physical-reasoning systems interact? Evidence from priming effects with object arrays or novel labels

How do infants reason about simple physical events such as containment, tube, and support events? According to the two-system model, two cognitive systems, the object-file (OF) and physical-reasoning (PR) systems, work together to guide infants' responses to these events. When an event begins, the OF system sends categorical information about the objects and their arrangements to the PR system. This system then categorizes the event, assigns event roles to the objects, and taps the OF system for information about features previously identified as causally relevant for the event category selected. All of the categorical and featural information included in the event's representation is interpreted by the PR system's domain knowledge, which includes core principles such as persistence and gravity. The present research tested a novel prediction of the model: If the OF system could be primed to also send, at the beginning of an event, information about an as-yet-unidentified feature, the PR system would then interpret this information using its core principles, allowing infants to detect core violations involving the feature earlier than they normally would. We examined this prediction using two types of priming manipulations directed at the OF system, object arrays and novel labels. In six experiments, infants aged 7-13 months (N = 304) were tested using different event categories and as-yet-unidentified features (color in containment events, height in tube events, and proportional distribution in support events) as well as different tasks (violation-of-expectation and action tasks). In each case, infants who were effectively primed reasoned successfully about the as-yet-unidentified feature, sometimes as early as six months before they would typically do so. These converging results provide strong support for the two-system model and for the claim that uncovering how the OF and PR systems represent and exchange information is essential for understanding how infants respond to physical events.

No effects of modality in development of locative expressions of space in signing and speaking children

Linguistic expressions of locative spatial relations in sign languages are mostly visually motivated representations of space involving mapping of entities and spatial relations between them onto the hands and the signing space. These are also morphologically complex forms. It is debated whether modality-specific aspects of spatial expressions modulate spatial language development differently in signing compared to speaking children. In a picture description task, we compared the use of locative expressions for containment, support, and occlusion relations by deaf children acquiring Turkish Sign Language and hearing children acquiring Turkish (age 3;5-9;11). Unlike previous reports suggesting a boosting effect of iconicity, and/or a hindering effect of morphological complexity of the locative forms in sign languages, our results show similar developmental patterns for signing and speaking children's acquisition of these forms. Our results suggest the primacy of cognitive development guiding the acquisition of locative expressions by speaking and signing children.

Experience With a Linguistic Variant Affects the Acquisition of Its Sociolinguistic Meaning: An Alien-Language-Learning Experiment

How do speakers learn the social meaning of different linguistic variants, and what factors influence how likely a particular social-linguistic association is to be learned? It has been argued that the social meaning of more salient variants should be learned faster, and that learners' pre-existing experience of a variant will influence its salience. In this paper, we report two artificial-language-learning experiments investigating this. Each experiment involved two language-learning stages followed by a test. The first stage introduced the artificial language and trained participants in it, while the second stage added a simple social context using images of cartoon aliens. The first learning stage was intended to establish participants' experience with the artificial language in general and with the distribution of linguistic variants in particular. The second stage, in which linguistic stimuli were accompanied by images of particular aliens, was intended to simulate the acquisition of linguistic variants in a social context. In our first experiment, we manipulated whether a particular linguistic variant, associated with one species of alien in the second learning phase, had been encountered in the first learning phase. In the second experiment, we manipulated whether the variant had been encountered in the same grammatical context. In both cases we predicted that the unexpectedness of a new variant or a new grammatical context for an old variant would increase the variant's salience and facilitate the learning of its social meaning. This is what we found, although in the second experiment, the effect was driven by better learners. Our results suggest that unexpectedness increases the salience of variants and makes their social distribution easier to learn, deepening our understanding of the role of individual language experience in the acquisition of sociolinguistic meaning.

12- and 24-Month-Old Infants' Search Behavior Under Informational Uncertainty

Infants register and react to informational uncertainty in the environment. They also form expectations about the probability of future events as well as update the expectation according to changes in the environment. A novel line of research has started to investigate infants' and toddlers' behavior under uncertainty. By combining these research areas, the present research investigated 12- and 24-month-old infants' searching behaviors under varying degree of informational uncertainty. An object was hidden in one of three possible locations and probabilistic information about the hiding location was manipulated across trials. Infants' time delay in search initiation for a hidden object linearly increased across the level of informational uncertainty. Infants' successful searching also varied according to probabilistic information. The findings suggest that infants modulate their behaviors based on probabilistic information. We discuss the possibility that infants' behavioral reaction to the environmental uncertainty constitutes the basis for the development of subjective uncertainty.

Development of basic intuitions about physical support during early childhood: Evidence from a novel eye-tracking paradigm

Using a novel eye-tracking paradigm, we assessed the development of 2- to 6-year-old children's intuitions about the physical support of symmetrical and asymmetrical objects in two experiments (Experiment 1: N = 98; Experiment 2: N = 288). Children were presented with video sequences demonstrating how two identical blocks were lowered onto a platform before being released simultaneously. In the critical test trials, both blocks remained in place although only one of them was sufficiently supported. As expected, children tended to look longer at the block, which should have fallen. Taken together, the results indicate that even 2-year-old children are sensitive to the amount of contact between symmetrical blocks and a supporting platform and even anticipate which block is going to fall. Nonetheless, we found a considerable improvement with age in this respect. Two-year-olds did not consider an object's weight distribution reliably when assessing its stability and even older preschoolers performed much more poorly with asymmetrical than symmetrical blocks. We conclude that intuitions about support are still weak and limited in toddlers and that they improve considerably during early childhood.

Are Different Actions Mediated by Distinct Systems of Knowledge in Infancy?

This chapter considers why studies of infant looking and reaching often suggest different patterns of cognitive and perceptual development. In some cases, convergent results have emerged from studies of infant looking and reaching, but differences are common. The most typical results suggest less adult-like perception and cognition in studies of reaching than in studies of looking. Several reaching studies, however, do not fit this pattern, suggesting that reaching actions may be mediated by distinct systems of knowledge and information processing. Comparisons of research on other behaviors, such as crawling and walking, also suggest that infant knowledge systems vary across actions. Research on how adult size perception differs between verbal and reaching response behaviors is considered and used as a template to interpret the developmental results. Like adults, when infants prepare to engage in particular actions, they seem to shift their sensitivity to particular sources of information and to process that information in action-relevant ways. These tendencies suggest that distinct knowledge systems mediate different actions in infancy.

The early social significance of shared ritual actions

Many rituals are socially stipulated such that engaging in a group's rituals can fundamentally signal membership in that group. Here, we asked whether infants infer information about people's social affiliation based on whether those people perform the same ritualistic action versus different actions. We presented 16-month-old infants with two people who used the same object to achieve the same goal: turning on a light. In a first study, the actions that the actors used to turn on the light had key properties of ritual: they were not causally necessary to reach the overall goal, and there were no features of the situation that required doing the particular actions. We varied whether the two actors performed the same action or performed different actions to turn on the light. Infants expected people who used the same ritualistic action to be more likely to affiliate than people who used different actions. A second study indicated that these results were not due to perceptual similarity: when the differences in the actors' actions were not marked by properties of ritual, but were instead due to situational constraints, infants expected the actors to affiliate. Thus, infants understand the social significance of people engaging in common, potentially ritualistic actions, and expect these actions to provide information about third-party social relationships.

Explanation-based learning in infancy

In explanation-based learning (EBL), domain knowledge is leveraged in order to learn general rules from few examples. An explanation is constructed for initial exemplars and is then generalized into a candidate rule that uses only the relevant features specified in the explanation; if the rule proves accurate for a few additional exemplars, it is adopted. EBL is thus highly efficient because it combines both analytic and empirical evidence. EBL has been proposed as one of the mechanisms that help infants acquire and revise their physical rules. To evaluate this proposal, 11- and 12-month-olds (n = 260) were taught to replace their current support rule (that an object is stable when half or more of its bottom surface is supported) with a more sophisticated rule (that an object is stable when half or more of the entire object is supported). Infants saw teaching events in which asymmetrical objects were placed on a base, followed by static test displays involving a novel asymmetrical object and a novel base. When the teaching events were designed to facilitate EBL, infants learned the new rule with as few as two (12-month-olds) or three (11-month-olds) exemplars. When the teaching events were designed to impede EBL, however, infants failed to learn the rule. Together, these results demonstrate that even infants, with their limited knowledge about the world, benefit from the knowledge-based approach of EBL.

What Develops in Infants' Spatial Categorization? Korean Infants' Categorization of Containment and Tight-Fit Relations

Korean-learning infants' categorization of two spatial categories, one consistent and one inconsistent with the Korean semantic category of "kkita," was examined. Infants of 10 months (n = 32) and 18 months (n = 49) were tested on their categorization of containment or tight fit spatial relations. At 10 months, infants only formed a category of containment, but at 18 months, their categorization of tight fit was significantly stronger than containment. The results suggest that Korean infants benefit from their language environment in forming a category of tight fit when the exemplars are perceptually diverse. In particular, infants' language environment may bolster their ability to generalize across diverse exemplars to form abstract categorical representations of spatial relations.

Trading Spaces: Carving up Events for Learning Language

Relational terms (e.g., verbs and prepositions) are the cornerstone of language development, bringing together two distinct fields: linguistic theory and infants’ event processing. To acquire relational terms such as run, walk, in, and on, infants must first perceive and conceptualize components of dynamic events such as containment—support, path—manner, source—goal, and figure—ground. Infants must then uncover how the particular language they are learning encodes these constructs. This review addresses the interaction of language learning with infants’ conceptualization of these nonlinguistic spatial event components. We present the thesis that infants start with language-general nonlinguistic constructs that are gradually refined and tuned to the requirements of their native language. In effect, infants are trading spaces, maintaining their sensitivity to some relational distinctions while dampening other distinctions, depending on how their native language expresses these constructs.

Building machines that learn and think like people

Recent progress in artificial intelligence has renewed interest in building systems that learn and think like people. Many advances have come from using deep neural networks trained end-to-end in tasks such as object recognition, video games, and board games, achieving performance that equals or even beats that of humans in some respects. Despite their biological inspiration and performance achievements, these systems differ from human intelligence in crucial ways. We review progress in cognitive science suggesting that truly human-like learning and thinking machines will have to reach beyond current engineering trends in both what they learn and how they learn it. Specifically, we argue that these machines should (1) build causal models of the world that support explanation and understanding, rather than merely solving pattern recognition problems; (2) ground learning in intuitive theories of physics and psychology to support and enrich the knowledge that is learned; and (3) harness compositionality and learning-to-learn to rapidly acquire and generalize knowledge to new tasks and situations. We suggest concrete challenges and promising routes toward these goals that can combine the strengths of recent neural network advances with more structured cognitive models.

Infants Actively Construct and Update Their Representations of Physical Events: Evidence from Change Detection by 12-Month-Olds

The present research investigates the effects of top-down information on 12-month-olds’ representations of physical events, focusing on their ability to detect an object change across different events. Infants this age typically fail to detect height changes in events with tubes even though they successfully do so in events with covers. In Experiment  1, infants who saw a tube event in which objects did not interact successfully detected a change in an object’s height, suggesting that object interaction affects infants’ categorization of physical events. Experiments 2 and 3 examined the fine-grained process of event representation. In Experiment  2, infants detected the change in the tube event if they were led by pretest exposure to believe that the event was conducted with a cover. In Experiment  3, infants who initially believed so updated their representation if shown a tube before object interaction occurred (but not after). Together, these findings provide new evidence that infants, like older children and adults, actively construct physical events. Whether they notice a change depends on their existing knowledge and the current representation of the event.

Now You See It, Now You Don’t

The cognitive ability of dogs can be assessed using tasks from the human developmental literature. A task that appears to have ecological relevance is the object-permanence task, in which performance hinges on understanding that an object continues to exist once it can no longer be seen. Although dogs are good at visible displacement tasks, in which an object disappears into a container, they can also understand an invisible displacement, in which the container holding the object is moved. Furthermore, we have found that dogs are able to show considerable memory for the invisibly displaced object. We have also found evidence for object permanence in dogs using the violation-of-expectancy procedure, in which subjects look longer at a stimulus that violates expectations (a screen that appears to pass through an object that has been placed behind the screen) than one that does not. Similarly, we have found that dogs look longer at an object that appears to have changed color or size after being placed behind a screen compared to an object that has not changed. Object-permanence tasks provide an ecologically relevant means of evaluating the cognitive development of dogs.

Innate Ideas Revisited: For a Principle of Persistence in Infants' Physical Reasoning

The notion of innate ideas has long been the subject of intense debate in the fields of philosophy and cognitive science. Over the past few decades, methodological advances have made it possible for developmental researchers to begin to examine what innate ideas-what innate concepts and principles-might contribute to infants ' knowledge acquisition in various core domains. This article focuses on the domain of physical reasoning and on Spelke's (1988, 1994) proposal that principles of continuity and cohesion guide infants' interpretation of physical events. The article reviews recent evidence that these two principles are in fact corollaries of a single and more powerful principle of persistence, which states that objects persist, as they are, in time and space.

Adult humans' understanding of support relations: an up-linkage replication

In an up-linkage replication, three experiments examined adult humans' folk physics, i.e., their naturally occurring and spontaneous understanding of the physical world, using a violation of expectation (VOE) task and stimuli similar to those used to study chimpanzees', monkeys', and rooks' folk physics. Unlike what has been reported with nonhuman primates, adult humans did not look longer at physically impossible than possible events, though they did rate the physically impossible events as more interesting and novel than the possible events. These results underscore that behavior during a VOE experiment has many possible causes, only one of which may be a subject's folk physics.

The use of a displacement device negatively affects the performance of dogs (Canis familiaris) in visible object displacement tasks

Visible and invisible displacement tasks have been used widely for comparative studies of animals' understanding of object permanence, with evidence accumulating that some species can solve invisible displacement tasks and, thus, reach Piagetian stage 6 of object permanence. In contrast, dogs appear to rely on associative cues, such as the location of the displacement device, during invisible displacement tasks. It remains unclear, however, whether dogs, and other species that failed in invisible displacement tasks, do so because of their inability to form a mental representation of the target object, or simply because of the involvement of a more salient but potentially misleading associative cue, the displacement device. Here we show that the use of a displacement device impairs the performance of dogs also in visible displacement tasks: their search accuracy was significantly lower when a visible displacement was performed with a displacement device, and only two of initially 42 dogs passed the sham-baiting control conditions. The negative influence of the displacement device in visible displacement tasks may be explained by strong associative cues overriding explicit information about the target object's location, reminiscent of an overshadowing effect, and/or object individuation errors as the target object is placed within the displacement device and moves along a spatiotemporally identical trajectory. Our data suggest that a comprehensive appraisal of a species' performance in object permanence tasks should include visible displacement tasks with the same displacement device used in invisible displacements, which typically has not been done in the past.

(The Feeling of) Meaning-as-Information

The desire for meaning is recognized as a central human motive. Yet, knowing that people want meaning does not explain its function. What adaptive problem does this experience solve? Drawing on the feelings-as-information hypothesis, we propose that the feeling of meaning provides information about the presence of reliable patterns and coherence in the environment, information that is not provided by affect. We review research demonstrating that manipulations of stimulus coherence influence subjective reports of meaning in life but not affect. We demonstrate that manipulations that foster an associative mindset enhance meaning. The meaning-as-information perspective embeds meaning in a network of foundational functions including associative learning, perception, cognition, and neural processing. This approach challenges assumptions about meaning, including its motivational appeal, the roles of expectancies and novelty in this experience, and the notion that meaning is inherently constructed. Implications for constructed meaning and existential meanings are discussed.

Friends or foes: infants use shared evaluations to infer others' social relationships

Predicting others' affiliative relationships is critical to social cognition, but there is little evidence of how this ability develops. We examined 9-month-old infants' inferences about 3rd-party affiliation based on shared and opposing evaluations. Infants expected 2 people who expressed shared evaluations to interact positively, whereas they expected 2 people who expressed opposing evaluations to interact negatively. A control condition revealed that infants' expectations could not be due to mere perceptual repetition. Thus, an abstract understanding that 3rd-party affiliation can be based on shared intentions has roots in the 1st year of life. These findings have implications for understanding humans' earliest representations of the social world.

Development of Intuitive Statics

Previous research on the development of intuitive statics has revealed that preschoolers’ ability to judge the stability of asymmetrically shaped objects is severely limited ( Krist, 2010 ). To overrule the objection that this limitation is caused by extraneous task demands, the original task was simplified by eliminating the need to judge the stability of varied objects consecutively in a series of trials. Three- and 4-year-old children (N = 65) were presented with L-shaped blocks either sufficiently supported by a platform or not. In six experimental trials, children had to judge whether the respective block would fall if released. In agreement with previous results, children exhibited great difficulties judging the stability of the asymmetrically shaped objects. Only 4-year-olds performed reliably above chance, whereas 3-year-olds answered at a chance level. It could thus be confirmed that preschoolers’ difficulties judging the stability of asymmetrically shaped objects are not merely due to extraneous task demands.

Infants use compression information to infer objects' weights: examining cognition, exploration, and prospective action in a preferential-reaching task

The present research used a preferential-reaching task to examine whether 9- and 11-month-olds (n=144) could infer the relative weights of two objects resting on a soft, compressible platform. Experiment 1 established that infants reached preferentially for the lighter of 2 boxes. In Experiments 2-4, infants saw 2 boxes identical except in weight resting on a cotton wool platform. Infants reached prospectively for the lighter box, but only when their initial exploratory activities provided critical information. At 11 months, infants succeeded as long as they first determined that the platform was compressible; at 9 months, infants succeeded only if they also explored the boxes and thus had advance knowledge that they differed in weight.

The comparator model of infant visual habituation and dishabituation: recent insights

Current knowledge of the perceptual and cognitive abilities in infancy is largely based on the visual habituation-dishabituation method. According to the comparator model [e.g., Sokolov (1963a) Perception and the conditioned reflex. Oxford: Pergamon Press], habituation refers to stimulus encoding and dishabituation refers to discriminatory memory performance. The review also describes the dual-process theory and the attention disengagement approach. The dual-process theory points to the impact of natural stimulus preferences on habituation-dishabituation processes. The attention disengagement approach emphasizes the contribution of the ability to shift the attention away from a stimulus. Moreover, arguments for the cognitive interpretation of visual habituation and dishabituations are discussed. These arguments are provided by physiological studies and by research on interindividual differences. Overall, the review shows that current research supports the comparator model. It emphasizes that the investigation of habituation and dishabituation expands our understanding of visual attention processes in infants.

Object Individuation and Physical Reasoning in Infancy: An Integrative Account

Much of the research on object individuation in infancy has used a task in which two different objects emerge in alternation from behind a large screen, which is then removed to reveal either one or two objects. In their seminal work, Xu and Carey (1996) found that it is typically not until the end of the first year that infants detect a violation when a single object is revealed. Since then, a large number of investigations have modified the standard task in various ways and found that young infants succeed with some but not with other modifications, yielding a complex and unwieldy picture. In this article, we argue that this confusing picture can be better understood by bringing to bear insights from a related subfield of infancy research, physical reasoning. By considering how infants reason about object information within and across physical events, we can make sense of apparently inconsistent findings from different object-individuation tasks. In turn, object-individuation findings deepen our understanding of how physical reasoning develops in infancy. Integrating the insights from physical-reasoning and object-individuation investigations thus enriches both subfields and brings about a clearer account of how infants represent objects and events.

Who is crossing where? Infants' discrimination of figures and grounds in events

To learn relational terms such as verbs and prepositions, children must first dissect and process dynamic event components. This paper investigates the way in which 8- to 14-month-old English-reared infants notice the event components, figure (i.e., the moving entity) and ground (i.e., stationary setting), in both dynamic (Experiment 1) and static representations of events (Experiment 2) for categorical ground distinctions expressed in Japanese, but not in English. We then compare both 14- and 19-month-old English- and Japanese-reared infants' processing of grounds to understand how language learning interacts with the conceptualization of these constructs (Experiment 3). Results suggest that (1) infants distinguish between figures and grounds in events; (2) they do so differently for static vs. dynamic displays; (3) early in the second year, children from diverse language environments form nonnative - perhaps universal - event categories; and (4) these event categories shift over time as children have more exposure to their native tongue.

Intuitive physical reasoning about occluded objects by inexperienced chicks

Questions concerning the role of nature and nurture in higher cognition appear to be intractable if one restricts one's attention to development in humans. However, in other domains, such as sensory development, much information has been gained from controlled rearing studies with animals. Here, we used a similar experimental strategy to investigate intuitive reasoning about occluded objects. Newborn domestic chicks (Gallus gallus) were reared singly with a small object that became their social partner. They were then accustomed to rejoin such an imprinting object when it was made to move and disappear behind either one of two identical opaque screens. After disappearance of the imprinting object, chicks were faced with two screens of different slants, or of different height or different width, which may or may not have been compatible with the presence of the imprinting object hidden beneath/behind them. Chicks consistently chose the screen of slant/height/width compatible with the presence of the object beneath/behind it. Preventing chicks from touching and pecking at the imprinting object before testing did not affect the results, suggesting that intuitive reasoning about physical objects is largely independent of specific experience of interaction with objects and of objects' occluding events.

The case of the disappearing bone: dogs' understanding of the physical properties of objects

To assess dogs' memory for an occluded object, a gaze duration procedure was used similar to one often used with nonverbal infants. A bone shaped dog biscuit was placed behind a solid screen that then rotated in the depth plane through an arc front to back. Dogs were shown either of the two test events. In one event (the possible event), the screen rotated until it reached the point at which it would have reached the bone and then stopped (about 120°); in the other event (the impossible event), the screen rotated through a full 180° arc, as though it had passed through the bone. The dogs looked significantly longer at the impossible event. To control for the differential time it took for the screen to move, for a control group, a bone was placed behind the screen and the screen was rotated either 60° or 120° (both possible events). No difference in looking time was found. To control for the movement of the screen through 120° or 180° when both were possible, for a second control group, the bone was placed to the side of the screen rather than behind the screen and the screen was moved 120° or 180°. Again, no significant difference in looking time was found. Results suggest that much like young children, dogs understand the physical properties of an occluded object. That is they appear to understand that an object (such as a screen) should not be able to pass through another object (such as dog bone).

Rooks perceive support relations similar to six-month-old babies

Some corvids have demonstrated cognitive abilities that rival or exceed those of the great apes; for example, tool use in New Caledonian crows, and social cognition, episodic-like memory and future planning in Western scrub-jays. Rooks appear to be able to solve novel tasks through causal reasoning rather than simple trial-and-error learning. Animals with certain expectations about how objects interact would be able to narrow the field of candidate causes substantially, because some causes are simply 'impossible'. Here we present evidence that rooks hold such expectations and appear to possess perceptual understanding of support relations similar to that demonstrated by human babies, which is more comprehensive than that of chimpanzees.

Occlusion is hard: Comparing predictive reaching for visible and hidden objects in infants and adults

Infants can anticipate the future location of a moving object and execute a predictive reach to intercept the object. When a moving object is temporarily hidden by darkness or occlusion, 6-month-old infants' reaching is perturbed but performance on darkness trials is significantly better than occlusion trials. How does this reaching behavior change over development? Experiment 1 tested predictive reaching of 6- and 9-month-old infants. While there was an increase in the overall number of reaches with increasing age, there were significantly fewer predictive reaches during the occlusion compared to visible trials and no age-related changes in this pattern. The decrease in performance found in Experiment 1 is likely to apply not only to the object representations formed by infants but also those formed by adults. In Experiment 2 we tested adults with a similar reaching task. Like infants, the adults were most accurate when the target was continuously visible and performance in darkness trials was significantly better than occlusion trials, providing evidence that there is something specific about occlusion that makes it more difficult than merely lack of visibility. Together, these findings suggest that infants' and adults' capacities to represent objects have similar signatures throughout development.

Occlusion is hard: Comparing predictive reaching for visible and hidden objects in infants and adults

Infants can anticipate the future location of a moving object and execute a predictive reach to intercept the object. When a moving object is temporarily hidden by darkness or occlusion, 6-month-old infants' reaching is perturbed but performance on darkness trials is significantly better than occlusion trials. How does this reaching behavior change over development? Experiment 1 tested predictive reaching of 6- and 9-month-old infants. While there was an increase in the overall number of reaches with increasing age, there were significantly fewer predictive reaches during the occlusion compared to visible trials and no age-related changes in this pattern. The decrease in performance found in Experiment 1 is likely to apply not only to the object representations formed by infants but also those formed by adults. In Experiment 2 we tested adults with a similar reaching task. Like infants, the adults were most accurate when the target was continuously visible and performance in darkness trials was significantly better than occlusion trials, providing evidence that there is something specific about occlusion that makes it more difficult than merely lack of visibility. Together, these findings suggest that infants' and adults' capacities to represent objects have similar signatures throughout development.

Young infants' reasoning about physical events involving inert and self-propelled objects

The present research examined whether 5- to 6.5-month-old infants would hold different expectations about various physical events involving a box after receiving evidence that it was either inert or self-propelled. Infants were surprised if the inert but not the self-propelled box: reversed direction spontaneously (Experiment 1); remained stationary when hit or pulled (Experiments 3 and 3A); remained stable when released in midair or with inadequate support from a platform (Experiment 4); or disappeared when briefly hidden by one of two adjacent screens (the second screen provided the self-propelled box with an alternative hiding place; Experiment 5). On the other hand, infants were surprised if the inert or the self-propelled box appeared to pass through an obstacle (Experiment 2) or disappeared when briefly hidden by a single screen (Experiment 5). The present results indicate that infants as young as 5 months of age distinguish between inert and self-propelled objects and hold different expectations for physical events involving these objects, even when incidental differences between the objects are controlled. These findings are consistent with the proposal by Gelman, R. (1990). First principles organize attention to and learning about relevant data: Number and the animate-inanimate distinction as examples. Cognitive Science, 14, 79-106, Leslie, A. M. (1994). ToMM, ToBY, and Agency: Core architecture and domain specificity. In L. A. Hirschfeld & S. A. Gelman (Eds.), Mapping the mind: Domain specificity in cognition and culture (pp. 119-148). New York: Cambridge University Press, and others that infants endow self-propelled objects with an internal source of energy. Possible links between infants' concepts of self-propelled object, agent, and animal are also discussed.

Can infants be "taught" to attend to a new physical variable in an event category? The case of height in covering events

As they observe or produce events, infants identify variables that help them predict outcomes in each category of events. How do infants identify a new variable? An explanation-based learning (EBL) account suggests three essential steps: (1) observing contrastive outcomes relevant to the variable; (2) discovering the conditions associated with these outcomes; and (3) generating an explanation for the condition-outcome regularity discovered. In Experiments 1-3, 9-month-old infants watched events designed to "teach" them the variable height in covering events. After watching these events, designed in accord with the EBL account, the infants detected a height violation in a covering event, three months earlier than they ordinarily would have. In Experiments 4-6, the "teaching" events were modified to remove one of the EBL steps, and the infants no longer detected the height violation. The present findings thus support the EBL account and help specify the processes by which infants acquire their physical knowledge.