Bayesian orthodoxy posits a tight relationship between conditional probability and updating. Namely, the probability of an event "A" after learning "B" should equal the conditional probability of "A" given "B" prior to learning "B". We examine whether ordinary judgment conforms to the orthodox view. In three experiments we found substantial…

When students learn scientific theories that conflict with their earlier, naive theories, what happens to the earlier theories? Are they overwritten or merely suppressed? We investigated this question by devising and implementing a novel speeded-reasoning task. Adults with many years of science education verified two types of statements as quickly…

A central feature of human psychology is our pervasive tendency to divide the social world into "us" and "them". We prefer to associate with those who are similar to us over those who are different, preferentially allocate resources to similar others, and hold more positive beliefs about similar others. Here we investigate the developmental…

Recent research suggests that witnessing events of fission (e.g., the splitting of a solid object) impairs human infants', human adults', and non-human primates' object representations. The present studies investigated the reactions of gorillas and orangutans to cohesion violation across different types of fission events implementing a behavioral…

There is currently much controversy about which, if any, mental states chimpanzees and other nonhuman primates understand. In the current two studies we tested both chimpanzees' and human children's understanding of both knowledge-ignorance and false belief--in the same experimental paradigm involving competition with a conspecific. We found that…

This paper considers the role of comparison in the development of knowledge. Results show that comparing similar objects makes them appear more similar. Comparing dissimilar objects, on the other hand does not make them appear more similar, and in some circumstances may make them appear less similar. The effect of comparison on similar items was…

We hypothesized that women with Turner syndrome (45,X) with a single X-chromosome inherited from their mother may show mentalizing deficits compared to women of normal karyotype with two X-chromosomes (46,X). Simple geometrical animation events (two triangles moving with apparent intention in relation to each other) which usually elicit…

Forty-five children with mathematics learning disabilities, with and without comorbid reading disabilities, were compared to 45 normally achieving peers in tasks assessing basic numerical skills. Children with mathematics disabilities were only impaired when comparing Arabic digits (i.e., symbolic number magnitude) but not when comparing…

Eight experiments examined abilities of 3- to 4-year-olds to reorient themselves and locate a hidden object in an open circular space furnished with landmark objects. Findings showed that children failed to use geometric configuration of objects to reorient themselves. Children successfully located the object in relation to a geometric…

Compares the many-perspectives account of lexical acquisition--which proposes that children learn to take alternative perspectives along with the words they acquire--to the one-perspective account--which proposes that children are at first able to use only one term to talk about an object or event. Provides evidence from a variety of sources that…

Extends earlier work with American children to explore British children's application of teleological explanation to artifacts, biological properties, and properties of nonliving natural phenomena, based on the view that because of lower religiosity in Britain, these children might be less inclined than American children to endorse purpose-based…

Examined event-based memory in three groups of children between ages 14 and 25 months. Found that search task success was general in oldest group while performance was similar on a task in which success "may" have been due to recalling an object-removal event and one in which success could "only" have been due to recall of…

Argues that there is a social-cognitive and a social-perceptual component to a theory of mind. Presents as evidence three studies comparing children with Williams syndrome to children with Prader-Willi syndrome, and to children with nonspecific mental retardation. The findings suggest that only social-perceptual components of theory of mind, which…

Examined the degree of specificity encoded in early lexical representations by presenting 18- to 23-month-olds with object labels either correctly or incorrectly pronounced and analyzing children's eye movement. Found that children recognized the spoken words in both conditions but recognition was poorer when words were mispronounced, with effects…

Three experiments examined the relative importance of original function and current function in artifact categorization for young children and adults. It was concluded that 6-year-olds have begun to organize their understanding of artifacts around the notion of original function, whereas 4-year-olds have not. Data were examined in terms of how…