Non‐Bayesian Noun Generalization in 3‐ to 5‐Year‐Old Children: Probing the Role of Prior Knowledge in the Suspicious Coincidence Effect

It is unclear how children learn labels for multiple overlapping categories such as “Labrador,” “dog,” and “animal.” Xu and Tenenbaum (2007a) suggested that learners infer correct meanings with the help of Bayesian inference. They instantiated these claims in a Bayesian model, which they tested with preschoolers and adults. Here, we report data testing a developmental prediction of the Bayesian model—that more knowledge should lead to narrower category inferences when presented with multiple subordinate exemplars. Two experiments did not support this prediction. Children with more category knowledge showed broader generalization when presented with multiple subordinate exemplars, compared to less knowledgeable children and adults. This implies a U‐shaped developmental trend. The Bayesian model was not able to account for these data, even with inputs that reflected the similarity judgments of children. We discuss implications for the Bayesian model, including a combined Bayesian/morphological knowledge account that could explain the demonstrated U‐shaped trend.     

Short review and book note

G. J. Cuming and D. Baker, ed. Studies in church history, vol. 8: Popular belief and practice. Cambridge University Press, pp. xii and 331. £6.40.

James E. Wood, Jnr. (Ed.), Jewish-Christian relations in today's world (The Markham Press Fund of Baylor University Press, Waco, Texas, 1971) pp. 164.

Stern, S. M. and Walzer, Sofie, Three unknown Buddhist stories in an Arabic version, introduction, text and translation. Oxford, Cassirer, 1971, 38 pp. £2.00

Brown, Peter, Religion and society in the age of Saint Augustine, Faber and Faber, 1972, pp. 352. £3.25; MACINTYRE, ALASDAIR, Against the Self‐Images of the Age, Duckworth, 1871, pp. vi‐284. E3.45; WINCH, PETER, Ethics and Action, Routledge and Kegan Paul, 1972, pp. 231. £2.75.

Woodcock, George. Gandhi. Fontana, Collins (London), 1972. 108 pp., paperback 35p.

Masunaga, R. A primer of Soto Zen: A translation of Dogen's shobogenzo zuimonki. Routledge & Kegan Paul, 1972. 126 pp., £1.25.

Swanton, Michael (Ed.). The dream of the road. Manchester University Press, 1970. ix + 146 pp. £1.20 (paperback 60p).     

Neuropsychological Functioning in Children with Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) has been associated with deficits in the areas of verbal memory and learning, executive functioning, working memory, and attention in adults. Findings have been less consistent in the few studies examining neuropsychological functioning in childhood PTSD, which are often limited by comparing children with PTSD to children without trauma histories, making it unclear whether observed neuropsychological deficits are related to trauma exposure or to PTSD symptomatology. In an ethnically diverse sample of 62 children who witnessed intimate partner violence (n = 27 PTSD+ and 35 PTSD?), children with PTSD exhibited slower and less effective learning, heightened sensitivity to interference, and impaired effect of rehearsal on memory acquisition on the California Verbal Learning Test – Children's Version, a word list learning task. Both groups performed in the below average range on measures of executive functioning, attention, and intellectual ability.     

Corresponding delay-dependent biases in spatial language and spatial memory

The present study addresses the relationship between linguistic and non-linguistic spatial representations. In three experiments we probe spatial language and spatial memory at the same time points in the task sequence. Experiments 1 and 2 show analogous delay-dependent biases in spatial language and spatial memory. Experiment 3 extends this correspondence, showing that additional perceptual structure along the vertical axis reduces delay-dependent effects in both tasks. These results indicate that linguistic and non-linguistic spatial systems depend on shared underlying representational processes. In addition, we also address how these delay-dependent biases can arise within a single theoretical framework without positing differing prototypes for linguistic and non-linguistic spatial systems.     

Learn locally, think globally. Exemplar variability supports higher-order generalization and word learning

Research suggests that variability of exemplars supports successful object categorization; however, the scope of variability's support at the level of higher-order generalization remains unexplored. Using a longitudinal study, we examined the role of exemplar variability in first- and second-order generalization in the context of nominal-category learning at an early age. Sixteen 18-month-old children were taught 12 categories. Half of the children were taught with sets of highly similar exemplars; the other half were taught with sets of dissimilar, variable exemplars. Participants' learning and generalization of trained labels and their development of more general word-learning biases were tested. All children were found to have learned labels for trained exemplars, but children trained with variable exemplars generalized to novel exemplars of these categories, developed a discriminating word-learning bias generalizing labels of novel solid objects by shape and labels of nonsolid objects by material, and accelerated in vocabulary acquisition. These findings demonstrate that object variability leads to better abstraction of individual and global category organization, which increases learning outside the laboratory.     

Confronting complexity: insights from the details of behavior over multiple timescales

Young children tend to generalize novel names for novel solid objects by similarity in shape, a phenomenon dubbed 'the shape bias'. We believe that the critical insights needed to explain the shape bias in particular, and cognitive development more generally, come from Dynamic Systems Theory. We present two examples of recent work focusing on the real-time decision processes that underlie performance in the tasks used to measure the shape bias. We show how this work, and the dynamic systems perspective, sheds light on the controversy over the origins and development of the shape bias. In addition, we suggest that this dynamic systems perspective provides the right level for explanations of development because it requires a focus on the details of behavior over multiple timescales.     

Toddlers can adaptively change how they categorize: same objects,same session,two different categorical distinctions

Two experiments demonstrate that 14‐ to 18‐month‐old toddlers can adaptively change how they categorize a set of objects within a single session, and that this ability is related to vocabulary size. In both experiments, toddlers were presented with a sequential touching task with objects that could be categorized either according to some perceptually salient dimension corresponding to a taxonomic distinction (e.g. animals vs. vehicles) or to some less obvious dimension (e.g. rigid vs. deformable). In each experiment, children with larger productive vocabularies responded to both dimensions, showing evidence of sensitivity to each way of categorizing the items. Children with smaller productive vocabularies attended only to the taxonomically related categorical grouping. These experiments confirm that toddlers can adaptively shift the basis of their categorization and highlight the dynamic interaction between the child and the current task in early categorization.     

Different is good: connectionism and dynamic systems theory are complementary emergentist approaches to development

Connectionist and dynamic systems approaches to development are similar in that they are both emergentist theories that take a very different perspective from more traditional symbolic systems. Moreover, they are both based on similar mathematical principles. Nevertheless, connectionism and dynamic systems differ in the approach they take to the study of development. We argue that differences between connectionist and dynamic systems approaches in terms of the basic components of the models, what they see as the object of study, how they view the nature of knowledge and their notions of developmental change mean that they each stand to make different and unique contributions to a more complete theory of development. We present an example from our work on how children learn to learn words that illustrates the complementary nature of connectionist and dynamic systems theories.     

Effects of Environmental Uncertainty and Social Value Orientation in Resource Dilemmas

This study investigated the relationship between environmental uncertainty and social value orientation in a replenishable resource dilemma paradigm. One hundred seventy-two undergraduates harvested units from a common resource pool over 20 trials. Two levels of social value orientation (cooperative, noncooperative) were crossed with two levels of replenishment rate uncertainty (low, high). As predicted, noncooperators harvested significantly more resources than cooperators and high uncertainty subjects harvested more resources than low uncertainty subjects. The primary finding was the hypothesized three-way interaction among social value orientation, environmental uncertainty, and trials: Social value orientation moderated harvest decisionsonlyunder conditions of high uncertainty during the middle series of harvest trials. Noncooperators increased their harvests during this period, while cooperators harvested less and held their harvests constant across these trials. These results demonstrate that systematic individual differences exist in decision makers' responses to high environmental uncertainty. We suggest that social value orientation may exert its effect by influencing the scanning and processing of goal-relevant cues in this decision environment.