Fei Xu | University of California, Berkeley (original) (raw)
Papers by Fei Xu
Before the age of 4 months, infants make inductive inference s about the motions of physical obje... more Before the age of 4 months, infants make inductive inference s about the motions of physical objects. Developmental psychologists have provided verbal accounts of the knowledge that supports these inferences, but often these accounts focus on categorical rather than probabilistic principles. We propose that infant object perception is guided in part by probabilistic principles like persistence : things tend to remain the same, and when they change they do so gradually. To illustrate this idea we develop an ideal observer model that incorporates probabilistic principles of rigidity and inertia. Like previous researchers, we suggest that rigid motions are expected from an early age, but we challenge the previous claim that the inertia principle is relatively slow to develop [1]. We support these arguments by modeling several experiments from the developmental literature
Humans are typically able to infer how many objects their environment contains and to recognize w... more Humans are typically able to infer how many objects their environment contains and to recognize when the same object is encountered twice. W e present a simple statistical model that helps to explain these abilities and evaluate it in three behavioral experiments. Our first experiment suggests that humans rely on prior knowledge when deciding whether an object token has been previously encountered. Our second and third experiments suggest that humans can infer how many objects they have seen and can learn about categories and their properties even when they are uncertain about which tokens are instances of t he same object
This paper reports an experiment testing whether volitional control over the presentation of stim... more This paper reports an experiment testing whether volitional control over the presentation of stimuli leads to enhanced recognition memory in 6to 8-year-old children. Children were presented with a simple memory game on an iPad. During the study phase, for half of the materials children could decide the order and pacing of stimuli presentation (active condition). For the other half of the materials, children observed the study choices of another child (yoked condition). We found that recognition performance was better for the objects studied in the active condition as compared to the yoked condition. Furthermore, we found that the memory advantages of active learning persisted over a one-week delay between study and test. Our results support pedagogical approaches that emphasize self-guided learning and show that even young children benefit from being able to control how they learn.
Advances in child development and behavior, 2012
Cognitive Psychology, 2004
Cognition, 2000
Abstract 1. Replies to A. Needham and R. Baillargeon's (see record 2000-13570-002) comme... more Abstract 1. Replies to A. Needham and R. Baillargeon's (see record 2000-13570-002) commentary on the F. Xu et al (see record 1999-13941-002) study on infants' use of featural and experiential information in segregating and individuating objects. Xu et al are in ...
cwl.cogsci.rpi.edu
Keywords: Social cognition; Cognitive Development; Computational Modeling; Theory of Mind Adults ... more Keywords: Social cognition; Cognitive Development; Computational Modeling; Theory of Mind Adults effortlessly and automatically infer complex patterns of goals, beliefs, and other mental states as the causes of others' actions. Yet before the last decade little was known about the developmental origins of these abilities in early infancy. Our understanding of infant social cognition has now improved dramatically: even preverbal infants appear to perceive goals, preferences (Kushnir, Xu, & Wellman, in press), and even beliefs from ...
Trends in cognitive sciences, 1998
The study of object cognition over the past 25 years has proceeded in two largely non-interacting... more The study of object cognition over the past 25 years has proceeded in two largely non-interacting camps. One camp has studied object-based visual attention in adults, while the other has studied the object concept in infants. We briefly review both sets of literature and distill from the adult research a theoretical model that we apply to findings from the infant studies. The key notion in our model of object representation is the `sticky' index, a mechanism of selective attention that points at a physical object in a location. An object index does not represent any of the properties of the entity at which it points. However, once an index is pointing to an object, the properties of that object can be examined and featural information can be associated with, or `bound' to, its index. The distinction between indexing and feature binding underwrites the distinction between object individuation and object identification, a distinction that turns out to be crucial in both the ad...
Monographs of The Society for Research in Child Development, 1992
Children extend regular grammatical patterns to irregular words, resulting in overregularizations... more Children extend regular grammatical patterns to irregular words, resulting in overregularizations like comed, often after a period of correct performance ("U-shaped development"). The errors seem paradigmatic of rule use, hence bear on central issues in the psychology of rules: how creative rule application interacts with memorized exceptions in development, how overgeneral rules are unlearned in the absence of parental feedback, and whether cognitive processes involve explicit rules or parallel distributed processing (connectionist) networks. We remedy the lack of quantitative data on overregularization by analyzing 11,521 irregular past tense utterances in the spontaneous speech of 83 children. Our findings are as follows. (1) Overregularization errors are relatively rare (median 2.5% of irregular past tense forms), suggesting that there is no qualitative defect in children's grammars that must be unlearned. (2) Overregularization occurs at a roughly constant low rate from the 2s into the school-age years, affecting most irregular verbs. (3) Although overregularization errors never predominate, one aspect of their purported U-shaped development was confirmed quantitatively: an extended period of correct performance precedes the first error. (4) Overregularization does not correlate with increases in the number or proportion of regular verbs in parental speech, children's speech, or children's vocabularies. Thus, the traditional account in which memory operates before rules cannot be replaced by a connectionist alternative in which a single network displays rotelike or rulelike behavior in response to changes in input statistics. (5) Overregularizations first appear when children begin to mark regular verbs for tense reliably (i.e., when they stop saying Yesterday I walk). (6) The more often a parent uses an irregular form, the less often the child overregularizes it. (7) Verbs are protected from overregularization by similar-sounding irregulars, but they are not attracted to overregularization by similar-sounding regulars, suggesting that irregular patterns are stored in an associative memory with connectionist properties, but that regulars are not. We propose a simple explanation. Children, like adults, mark tense using memory (for irregulars) and an affixation rule that can generate a regular past tense form for any verb. Retrieval of an irregular blocks the rule, but children's memory traces are not strong enough to guarantee perfect retrieval. When retrieval fails, the rule is applied, and overregularization results.
Trends in Cognitive Sciences, 1998
Cognitive Psychology, 1996
Psychological Review, 2007
Before the age of 4 months, infants make inductive inference s about the motions of physical obje... more Before the age of 4 months, infants make inductive inference s about the motions of physical objects. Developmental psychologists have provided verbal accounts of the knowledge that supports these inferences, but often these accounts focus on categorical rather than probabilistic principles. We propose that infant object perception is guided in part by probabilistic principles like persistence : things tend to remain the same, and when they change they do so gradually. To illustrate this idea we develop an ideal observer model that incorporates probabilistic principles of rigidity and inertia. Like previous researchers, we suggest that rigid motions are expected from an early age, but we challenge the previous claim that the inertia principle is relatively slow to develop [1]. We support these arguments by modeling several experiments from the developmental literature
Humans are typically able to infer how many objects their environment contains and to recognize w... more Humans are typically able to infer how many objects their environment contains and to recognize when the same object is encountered twice. W e present a simple statistical model that helps to explain these abilities and evaluate it in three behavioral experiments. Our first experiment suggests that humans rely on prior knowledge when deciding whether an object token has been previously encountered. Our second and third experiments suggest that humans can infer how many objects they have seen and can learn about categories and their properties even when they are uncertain about which tokens are instances of t he same object
This paper reports an experiment testing whether volitional control over the presentation of stim... more This paper reports an experiment testing whether volitional control over the presentation of stimuli leads to enhanced recognition memory in 6to 8-year-old children. Children were presented with a simple memory game on an iPad. During the study phase, for half of the materials children could decide the order and pacing of stimuli presentation (active condition). For the other half of the materials, children observed the study choices of another child (yoked condition). We found that recognition performance was better for the objects studied in the active condition as compared to the yoked condition. Furthermore, we found that the memory advantages of active learning persisted over a one-week delay between study and test. Our results support pedagogical approaches that emphasize self-guided learning and show that even young children benefit from being able to control how they learn.
Advances in child development and behavior, 2012
Cognitive Psychology, 2004
Cognition, 2000
Abstract 1. Replies to A. Needham and R. Baillargeon's (see record 2000-13570-002) comme... more Abstract 1. Replies to A. Needham and R. Baillargeon's (see record 2000-13570-002) commentary on the F. Xu et al (see record 1999-13941-002) study on infants' use of featural and experiential information in segregating and individuating objects. Xu et al are in ...
cwl.cogsci.rpi.edu
Keywords: Social cognition; Cognitive Development; Computational Modeling; Theory of Mind Adults ... more Keywords: Social cognition; Cognitive Development; Computational Modeling; Theory of Mind Adults effortlessly and automatically infer complex patterns of goals, beliefs, and other mental states as the causes of others' actions. Yet before the last decade little was known about the developmental origins of these abilities in early infancy. Our understanding of infant social cognition has now improved dramatically: even preverbal infants appear to perceive goals, preferences (Kushnir, Xu, & Wellman, in press), and even beliefs from ...
Trends in cognitive sciences, 1998
The study of object cognition over the past 25 years has proceeded in two largely non-interacting... more The study of object cognition over the past 25 years has proceeded in two largely non-interacting camps. One camp has studied object-based visual attention in adults, while the other has studied the object concept in infants. We briefly review both sets of literature and distill from the adult research a theoretical model that we apply to findings from the infant studies. The key notion in our model of object representation is the `sticky' index, a mechanism of selective attention that points at a physical object in a location. An object index does not represent any of the properties of the entity at which it points. However, once an index is pointing to an object, the properties of that object can be examined and featural information can be associated with, or `bound' to, its index. The distinction between indexing and feature binding underwrites the distinction between object individuation and object identification, a distinction that turns out to be crucial in both the ad...
Monographs of The Society for Research in Child Development, 1992
Children extend regular grammatical patterns to irregular words, resulting in overregularizations... more Children extend regular grammatical patterns to irregular words, resulting in overregularizations like comed, often after a period of correct performance ("U-shaped development"). The errors seem paradigmatic of rule use, hence bear on central issues in the psychology of rules: how creative rule application interacts with memorized exceptions in development, how overgeneral rules are unlearned in the absence of parental feedback, and whether cognitive processes involve explicit rules or parallel distributed processing (connectionist) networks. We remedy the lack of quantitative data on overregularization by analyzing 11,521 irregular past tense utterances in the spontaneous speech of 83 children. Our findings are as follows. (1) Overregularization errors are relatively rare (median 2.5% of irregular past tense forms), suggesting that there is no qualitative defect in children's grammars that must be unlearned. (2) Overregularization occurs at a roughly constant low rate from the 2s into the school-age years, affecting most irregular verbs. (3) Although overregularization errors never predominate, one aspect of their purported U-shaped development was confirmed quantitatively: an extended period of correct performance precedes the first error. (4) Overregularization does not correlate with increases in the number or proportion of regular verbs in parental speech, children's speech, or children's vocabularies. Thus, the traditional account in which memory operates before rules cannot be replaced by a connectionist alternative in which a single network displays rotelike or rulelike behavior in response to changes in input statistics. (5) Overregularizations first appear when children begin to mark regular verbs for tense reliably (i.e., when they stop saying Yesterday I walk). (6) The more often a parent uses an irregular form, the less often the child overregularizes it. (7) Verbs are protected from overregularization by similar-sounding irregulars, but they are not attracted to overregularization by similar-sounding regulars, suggesting that irregular patterns are stored in an associative memory with connectionist properties, but that regulars are not. We propose a simple explanation. Children, like adults, mark tense using memory (for irregulars) and an affixation rule that can generate a regular past tense form for any verb. Retrieval of an irregular blocks the rule, but children's memory traces are not strong enough to guarantee perfect retrieval. When retrieval fails, the rule is applied, and overregularization results.
Trends in Cognitive Sciences, 1998
Cognitive Psychology, 1996
Psychological Review, 2007