Content uploaded by Layla Unger
Author content
All content in this area was uploaded by Layla Unger on Nov 26, 2014
Content may be subject to copyright.
A preview of the PDF is not available
Developmental Changes in the Semantic Organization of Living Kinds
Abstract and Figures
Semantic knowledge contains information about both individual concepts and relationships between concepts. Relationships come in many forms, including taxonomic and thematic, and are critical for converting collections of attributes known about each entity into an interconnected web of semantic knowledge. According to computational modeling studies, increasing knowledge about entities and their relationships should support increasing elaboration in the organizational structure of semantic knowledge. In contrast, extant empirical research has presented a static picture of the developmental trajectory of semantic organization, in which concepts remain organized according to thematic relations into adulthood. The current developmental study introduces methodological innovations designed to overcome limitations that may have skewed the developmental trajectory described in prior studies. The picture that has emerged from this study reflects dramatic changes in semantic organization from preschool age to adulthood, in which an initially limited grasp of multiple types of relations expands and becomes increasingly robust with age.
Figures - uploaded by Layla Unger
Author content
All figure content in this area was uploaded by Layla Unger
Content may be subject to copyright.
... However, development and learning concepts become increasingly differentiated into groups that capture a larger number of more subtle relationships, leading to the formation of Btaxonomic^clusters. There is recent evidence that this developmental trajectory characterizes changes in representational similarity not only in computational models but also in human participants (Fisher, Godwin, Matlen, & Unger, 2014;Unger, Fisher, & MacLellan, 2014). Therefore, developmental changes in representational similarity explain why Sloman's feature-based model would provide a good fit to performance of older children (whose representational similarity of familiar categories is in many ways similar to that in adults) but not that of preschoolers (whose representational similarity of familiar categories is dramatically different from that of adults; Fisher et al., 2014;. ...
... In addition to being able to account for several inconsistencies in the literature, the PaRS account can generate new predictions. Recall that early in development, semantic representations are poorly differentiated but become increasingly differentiated in accordance with taxonomic relations in the course of learning and development Hills, et al., 2009;Kemp & Tenenbaum 2008;Rogers & McClelland, 2004;Unger et al., 2014). For example, Unger et al. (2014) observed that preschoolers and kindergarteners were likely to group together items, such as whale, seaweed, and water lily (likely due to similarity in habitat); however, by second grade children grouped items largely in accordance with the plants-animals distinction. ...
... Recall that early in development, semantic representations are poorly differentiated but become increasingly differentiated in accordance with taxonomic relations in the course of learning and development Hills, et al., 2009;Kemp & Tenenbaum 2008;Rogers & McClelland, 2004;Unger et al., 2014). For example, Unger et al. (2014) observed that preschoolers and kindergarteners were likely to group together items, such as whale, seaweed, and water lily (likely due to similarity in habitat); however, by second grade children grouped items largely in accordance with the plants-animals distinction. ...
Category-based reasoning is central to mature cognition; yet, the developmental course of this fundamental ability remains unclear. We designed a longitudinal study to investigate the development of category-based reasoning. We also took an individual differences approach to identify possible cognitive factors that may facilitate category-based reasoning. In this paper we report preliminary results of our longitudinal investigation into the development of category-based reasoning.
... However, development and learning concepts become increasingly differentiated into groups that capture a larger number of more subtle relationships, leading to the formation of "taxonomic" clusters. There is recent evidence that this developmental trajectory characterizes changes in representational similarity not only in computational models but also in human participants (Fisher, Godwin, Matlen, & Unger, 2014; Unger, Fisher, & MacLellan, 2014. Therefore, developmental changes in representational similarity explain why Sloman's featurebased model would provide a good fit to performance of older children (whose representational similarity of familiar categories is in many ways similar to that in adults) but not that of preschoolers (whose representational similarity of familiar categories is dramatically different from that of adults; Fisher et al., 2014. ...
... Recall that early in development, semantic representations are poorly differentiated but become increasingly differentiated in accordance with taxonomic relations in the course of learning and development ; Hills, et al., 2009; Kemp & Tenenbaum 2008; Rogers & McClelland, 2004. For example, Unger et al. ( 2014 ) observed that preschoolers and kindergarteners were likely to group together items, such as whale, seaweed, and water lily (likely due to similarity in habitat); however, by second grade children grouped items largely in accordance with the plants-animals distinction. ...
Inductive generalization is ubiquitous in human cognition. In the developmental literature, two different theoretical accounts of this important process have been proposed: a naïve theory account and a similarity-based account. However, a number of recent findings cannot be explained within the existing theoretical accounts. We describe a revised version of the similarity-based account of inductive generalization with familiar categories. We tested the novel predictions of this account in two reported studies with 4-year-old children (N = 57). The reported studies include the first short-term longitudinal investigation of the development of children's induction with familiar categories, and it is the first study to explore the role of individual differences in semantic organization, general intelligence, working memory, and inhibition in children's induction.
... La categorización es un componente fundamental de la cognición y una herramienta muy poderosa para organizar lo que, de otro modo, sería un mundo caótico, debido al inconmensurable volumen de información al que estamos expuestos, y a nuestras capacidades de procesamiento limitadas (Fisher, Godwin, Matlen, & Unger, 2015;Johansen, Savage, Fouquet, & Shanks, 2015;Unger, Fisher, Nugent, Ventura, & MacLellan, 2016). Tradicionalmente, la atención se ha centrado en la categorización taxonómica, basada en que sus miembros comparten propiedades, formando una clase (e.g., animal o mueble), pero existen otras formas de categorización, como la perceptiva, guiada por los atributos físicos de los objetos, y la temática, que se rige por relaciones espaciales y/o temporales de contigüidad e involucra miembros heterogéneos que pertenecen a un mismo evento o escena (Antonucci & Alt, 2011;Estes, Golonka, & Jones, 2011;Landrigan & Mirman, 2017;Lewis, Poeppel, & Murphy, 2015;Sadeghi, McClelland, & Hoffman, 2015;Unger, Fisher, & MacLellan, 2014;Unger et al., 2016). ...
Pese a la abundante evidencia de que los niños pueden categorizar perceptiva, temática y taxonómicamente, pocos estudios indagan si los patrones hallados en adultos -asociación de seres vivos con atributos taxonómicos y perceptivos, y de objetos con información temática- se encuentran también en población infantil. Por eso el objetivo del trabajo fue estudiar los tipos de atributos -principalmente taxonómicos y temáticos- utilizados por niños de 6 a 11 años de 1º, 3º y 5º año de educación primaria de Mar del Plata, mediante una tarea que consistió en solicitar características de conceptos de seres vivos y no vivos (ANIMALES, FRUTAS, OBJETOS y MUEBLES). Las relaciones temáticas predominaron en los OBJETOS y MUEBLES y no en las FRUTAS y ANIMALES, en apoyo a la idea de que las características contextuales y funcionales son más importantes para reconocer y describir artefactos que seres vivos. Las relaciones taxonómicas primaron en los ANIMALES y FRUTAS, y no en los OBJETOS y MUEBLES, avalando la idea de que las relaciones taxonómicas, por su vinculación con el procesamiento visual, son más pertinentes para reconocer y categorizar seres vivos.
... Children's ability to make taxonomic matches in the presence of perceptual lures (e.g., chocolate cakeslice of birthday cake-brown top-hat) or thematic lures (e.g., carrot-rabbit-tomato) improves gradually between three and six years of age. Similar trends emerge in free sorting tasks in which children are asked to sort a number of items that can be cross-classified into multiple groups (Blaye et al., 2006;Unger et al., 2014). Specifically, 4-year-old children often produce idiosyncratic groupings or thematic groupings, whereas by 8 years of age children's thematic groupings become embedded within taxonomic groupings. ...
Inductive generalization is ubiquitous in human cognition; however, the factors underpinning this ability early in development remain contested. The present study was designed to (1) test the predictions of the naïve theory and a similarity-based account and (2) examine the mechanism by which labels promote induction. In Experiment 1, 3- to 5-year-old children made inferences about highly familiar categories. The results were not fully consistent with either theoretical account. In contrast to the predictions of the naïve theory approach, the youngest children in the study did not ignore perceptually compelling lures in favor of category-match items; in contrast to the predictions of the similarity-based account, no group of participants favored perceptually compelling lures in the presence of dissimilar-looking category-match items. In Experiment 2 we investigated the mechanisms by which labels promote induction by examining the influence of different label types, namely category labels (e.g., the target and category-match both labeled as bird) and descriptor labels (e.g., the target and the perceptual lure both labeled as brown) on induction performance. In contrast to the predictions of the naïve theory approach, descriptor labels but not category labels affected induction in 3-year-old children. Consistent with the predictions of the similarity-based account, descriptor labels affected the performance of children in all age groups included in the study. The implications of these findings for the developmental account of induction are discussed.
In our recent book, we present a parallel distributed processing theory of the acquisition, representation and use of human semantic knowledge. The theory proposes that semantic abilities arise from the flow of activation amongst simple, neuron-like processing units, as governed by the strengths of interconnecting weights; and that acquisition of new semantic information involves the gradual adjustment of weights in the system in response to experience. These simple ideas explain a wide range of empirical phenomena from studies of categorization, lexical acquisition, and disordered semantic cognition. In this précis we focus on phenomena central to the reaction against similarity-based theories that arose in the 1980's and that subsequently motivated the "theory-theory" approach to semantic knowledge. Specifically, we consider i) how concepts differentiate in early development, ii) why some groupings of items seem to form "good" or coherent categories while others do not, iii) why different properties seem central or important to different concepts, iv) why children and adults sometimes attest to beliefs that seem to contradict their direct experience, v) how concepts reorganize between the ages of 4 and 10, and vi) the relationship between causal knowledge and semantic knowledge. The explanations for these phenomena are illustrated with reference to a simple feed-forward connectionist model; and the relationship between this simple model, the broader theory, and more general issues in cognitive science are discussed.
This research explored the development of children's use of multiple conceptual organizations (thematic, taxonomic) in sorting sets of pictures. Experiment 1 revealed that between 5 and 9 years, two forms of categorical flexibility can be distinguished: response and conceptual flexibility. It appeared that children's multiple sorts do not necessarily reflect the use of different conceptual organizations. Such a lag was mainly due to a difficulty in accessing taxonomic representations, specifically in the younger age groups. Therefore, Experiment 2 investigated the development of taxonomic representations using an original approach requiring participants to decide whether new items could be included into an existing taxonomic sort. This approach showed that taxonomic representations were only gradually differentiated from thematic and perceptual ones over the 5 to 10 years period. The discussion raises new hypotheses about the interaction between developing executive control (specifically, increasing resistance to interference of irrelevant information) and increasing conceptual knowledge in accounting for the development of conceptual flexibility.
Children aged between 5 and 10 years old were tested on a semantic fluency (freelisting) task for two categories: animals and body parts. Additive tree analysis (Sattath & Tversky, 1977) was used to cluster items based upon both their proximity in the generated lists and their frequency of cooccurrence; the resulting trees, together with production frequency data, were compared across three age groups. For the animals category, this analysis revealed that although older children named proportionally more nonmammals, at all ages children tend to cluster animals according to their environmental context. For body parts, the analysis showed more parts, particularly internal organs, named with age and a cluster of face parts generated by all age groups. A novel feature of the current research was the use of statistical measures of additive tree similarity. The results are discussed with respect to theories of developmental change in the organisation of conceptual memory, and are viewed as supporting an assumption of continuity with age in the use of schematic relations in category structure. Insights are drawn from connectionist modelling to help explain the persistence, throughout childhood, of early forms of memory organisation.
Measurements of similarity have typically been obtained through the use of rating, sorting, and perceptual confusion tasks.
In the present paper, a new method for measuring similarity is described, in which subjects rearrange items so that their
proximity on a computer screen is proportional to their similarity. This method provides very efficient data collection. If
a display hasn objects, then, after subjects have rearranged the objects (requiring slightly more thann movements),n(n-1)/2 pairwise similarities can be recorded. As long as the constraints imposed by two-dimensional space are not too different
from those intrinsic to psychological similarity, the technique appears to offer an efficient, user-friendly, and intuitive
process for measuring psychological similarity.
How do we know what properties something has, and which of its properties should be generalized to other objects? How is the knowledge underlying these abilities acquired, and how is it affected by brain disorders? Our approach to these issues is based on the idea that cognitive processes arise from the interactions of neurons through synaptic connections. The knowledge in such interactive and distributed processing systems is stored in the strengths of the connections and is acquired gradually through experience. Degradation of semantic knowledge occurs through degradation of the patterns of neural activity that probe the knowledge stored in the connections. Simulation models based on these ideas capture semantic cognitive processes and their development and disintegration, encompassing domain-specific patterns of generalization in young children, and the restructuring of conceptual knowledge as a function of experience.
A fundamental part of growing up is going beyond routines. Children become increasingly skilled over the first years of life at actively maintaining goals in the service of flexible behavior, allowing them to break out of habits and switch from one task to another. Their early successes often occur with exogenous (externally-provided) goals, and only later with endogenous (internally-driven) goals--a developmental progression that may reflect the greater demands on selection processes inherent in deciding what to do. Three studies investigated the mechanisms supporting endogenous flexibility, using a verbal fluency task in which children generated members of a category and could decide on their own when to switch from one subcategory to another. Children's verbal fluency related to their performance in a more constrained and well-established switching task (Experiment 1), suggesting that the more complex verbal fluency measure taps the flexibility processes of interest. Children's verbal fluency was also linked to their abstract, categorical representations in both individual difference analyses (Experiment 2) and experimental manipulation (Experiment 3). We interpret these results in terms of the role of abstract representations in reducing selection demands to aid the development of endogenous control.
The shared features that characterize the noun categories that young children learn first are a formative basis of the human category system. To investigate the potential categorical information contained in the features of early-learned nouns, we examine the graph-theoretic properties of noun-feature networks. The networks are built from the overlap of words normatively acquired by children prior to 2(1/2) years of age and perceptual and conceptual (functional) features acquired from adult feature generation norms. The resulting networks have small-world structure, indicative of a high degree of feature overlap in local clusters. However, perceptual features--due to their abundance and redundancy--generate networks more robust to feature omissions, while conceptual features are more discriminating and, per feature, offer more categorical information than perceptual features. Using a network specific cluster identification algorithm (the clique percolation method) we also show that shared features among these early-learned nouns create higher-order groupings common to adult taxonomic designations. Again, perceptual and conceptual features play distinct roles among different categories, typically with perceptual features being more inclusive and conceptual features being more exclusive of category memberships. The results offer new and testable hypotheses about the role of shared features in human category knowledge.
This study explored the role of semantic structure within the domain of animal terms in children's and adults' spontaneous operations on these terms. Twenty-four subjects at each of six educational levels were given four tasks. Freelisting of animal terms and animal associations to animal words showed similar semantic structures across all educational levels, including doctoral students in zoology, with a few strongly associated terms, and a large group of fairly isolated terms. Sorting of animal terms and ratings of animal pair dissimilarities yielded a dominant dimension of size for grades seven, eleven, and undergraduate groups. The dominant dimension for zoologists, however, was based on food habits. The implications of these results for the development of semantic structures are discussed.
This article considers the semantic structure of the animal category from a cross-cultural developmental perspective. Children and adults from three North American communities (urban majority culture, rural majority culture and rural Native American) were prompted to generate animal names, and the resulting lists were analyzed for their underlying dimensionality and for the typicality or salience of specific animal names. The semantic structure of the animal category appeared to be consistent across cultural groups, but the relative salience of animal kinds varied as a function of culture and first-hand experience with the natural world. These results provide evidence of a shared representation of animals across disparate cultures but also indicate a role for culture in shaping animal concepts.
Is processing of conceptual information as robust as processing of perceptual information early in development? Existing empirical evidence is insufficient to answer this question. To examine this issue, 3- to 5-year-old children were presented with a flexible categorization task, in which target items (e.g., an open red umbrella) shared category membership with one test item (e.g., a folded umbrella) and perceptual characteristics with another test item (e.g., a red mushroom). Participants were instructed to either categorize stimuli by the same dimension (i.e., perceptual similarity or category membership) in both phases of the task, or switch from categorizing by one dimension to categorizing by the other dimension. Results pointed to a strong asymmetry in switch costs: conceptual switch costs were higher than perceptual switch costs. These results suggest that processing of perceptual information remains more robust than processing of conceptual information at least until 5 years of age.