Week 4

WEEK 4: HOW DO INFANTS REASON ABOUT PHYSICAL EVENTS? Introduction • Piaget concluded that young infants understand very little about physical events • Methodological concerns led investigators to seek alternative approaches for exploring young infants’ physical knowledge • The first wave established that, contrary to Piaget’s claims, even young infants possess some expectations about physical events • The second wave began to systematically examine the development of infants’ physical knowledge and brought to light striking patterns of successes and failures in infants’ responses to physical events • Finally, the third, ongoing wave builds on these preceding efforts and attempts to specify both how infants reason about physical events and what cognitive architecture makes this reasoning possible First Wave: The Competent Infant • One of the major alternative approaches used to explore young infants’ physical knowledge relies on the long-established finding that infants tend to look longer at stimuli they perceive to be novel as opposed to familiar • Looking-time tasks have two main advantages over action tasks • they can be administered to very young infants • they can be modified endlessly to explore subtle facets of infants’ responses to a wide array of physical event • Evidence that infants look reliably longer at the unexpected than at the expected event is taken to indicate that infants • possess the expectation under investigation • detect the violation in the unexpected event • are ‘surprised’ by this violation • Evidence that young infants are able to represent hidden objects • Evidence that young infants can represent hidden objects; they supported the notion that infants who reveal a physical expectation in a VOE task will reveal the same expectation in an action task as long as the demands of the task do not overwhelm their limited information-processing resources; and they helped put some of the concerns associated with VOE tasks Second Wave: Developmental Patterns • 4 month-olds were surprised when a wide object became fully hidden inside a narrow container, they were not surprised when a tall object became fully hidden inside a short container • 7.5 months of age, infants succeeded in detecting this violation - but they were not surprised if the tall object became fully hidden inside a short tube, instead of in inside a short container Developments Within Event Categories • Whether infants succeeded or failed at detecting a violation in an event category on the particular expectation investigated • Infants were surprised if an object remained hidden when passing behind a screen with a large opening extending from its lower edge WEEK 4: HOW DO INFANTS REASON ABOUT PHYSICAL EVENTS? • However, infants were not surprised if an object remained hidden when passing behind a screen with a large opening extending form its upper edge • 3.5 months of age, infants detected this violation, suggesting that they now attended to height information in occlusion events and expected tall objects to remain visible above short occluders • 4.5 months of age, infants were surprised if an object surreptitiously changed size or shape when passing behind a narrow screen • However, infants failed to detect other change violations: prior to 7.5 months, infants were not surprised if an object changed pattern when passing behind a narrow screen • Prior to about 11.5 months, infants were not surprised if an object changed color when passing behind a narrow screen Developments Across Event Categories • That there might be lags or decalages in infants acquisition of similar expectations in different event categories • One difficulty with this conclusion was that the events being compared often differed in so many dimensions that it made it difficult to determine exactly why infants succeeded with one event category but failed with another • Infants did not begin to attend to height information until about 12 months in covering events and until about 14.5 months in tube events • Prior to about 14.5 months, infants were not surprised if a tall object became fully hidden inside a short tube, they were not surprised if an object changed height when briefly lowered inside a tall tube and they tended to search for a tall object inside either a tall or a short tube Decalages With Perceptually Identical Events • Decalages have also been observed with perceptually identical events from different categories • Decalages are not due to the fact that infants generally have more difficulty reasoning about containers as opposed to occluders, about covers as opposed t containers, or about tubes as opposed to covers and containers Third Wave: An Account of Infants’ Physical Reasoning • Our account focuses on very simple situations where infants reason about one or two successive events involving a small number of objects • The events we investigate are by and large simple everyday events that would have been familiar to our distant evolutionary ancestors Physical-Reasoning System and Causal Framework • We assume that infants are born equipped with a physical reasoning (PR) system - an abstract, computational system that provides a skeletal causal framework for making sense of the displacements and interactions of objects and other physical entities • The PR system operates without conscious awareness: infants are not aware of the causal framework they use when reasoning about physical events • When infants watch a physical event, the PR system builds a specialized physical representation of the event WEEK 4: HOW DO INFANTS REASON ABOUT PHYSICAL EVENTS? • Any information included in this representation becomes subject to the system’s causal framework • This framework includes a number of explanatory concepts as well as core principles • Principles of persistence, which states that, all other things being equal, objects persist, as they are, in time and space • It specifies that an object cannot spontaneously appear or disappear (continuity), occupy the same space as another object (solidity), break apart (cohesion), fuse with another object (boundedness), or change size, shape, pattern, or color Basic Information • When building a physical representation for an event, the PR system first represents the basic information about the event • This basic information included both identity and spatio-temporal information • The identity formation provides broad categorical descriptors for the objects in the event: in particular, it specifies whether the objects are inert or self-propelled, human or non-human, and closed or open • The spatio-temporal; information specifies the spatial arrangement of the objects and how it changes as the event unfolds • Both the identity and the spatio-temporal information about an event help specify how many objects are involved in the event • The PR system uses the identity and the spatio-temporal information about an event to categorize the event and to assign appropriate roles to the objects in the event • The basic information about an event thus captures its essence: it specifies how many objects are involved in the event, what kinds of objects they are, what kind of event the objects are engaged in, and what role each object plays in the event • Detecting Basic Persistence Violations • In the first weeks of life, the PR system typically includes only basic information in its physical represent