The present study tested infants' ability to assess and compare quantities of a food substance. Contrary to previous findings, the results suggest that by 10 months of age infants can quantify non-cohesive substances, and that this ability is different in important ways from their ability to quantify discrete objects: (1) In contrast to even much…

Four-year-olds, 6-year-olds, and adults were asked to make judgments about the reality status of four different types of machines: real machines that children and adults interact with on a daily basis, real machines that children and adults interact with rarely (if at all), and impossible machines that violated a real-world physical or biological…

The ability to infer the referential intentions of speakers is a crucial part of learning a language. Previous research has uncovered various contextual and social cues that children may use to do this. Here we provide the first evidence that children also use speech disfluencies to infer speaker intention. Disfluencies (e.g. filled pauses "uh"…

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…

The current work explored the conditions under which infants generalize spatial relationships from one event to another. English-learning 5-month-olds habituated to a tight- or loose-fit covering event dishabituated to a change in fit during a "containment" test event, but infants habituated to a visually similar "occlusion" event did not. Thus,…

The current study evaluated the relative roles of conceptual knowledge and executive control on the development of "categorical flexibility," the ability to switch between simultaneously available but conflicting categorical representations of an object. Experiment 1 assessed conceptual knowledge and executive control together; Experiment 2…

The development of language indicating the emergence of thinking about the thoughts of self and others has been scarcely studied in Spanish-speaking children. For this reason, we studied the development of mental state language and various indicators of language development in 25 Spanish-speaking children assessed at 3, 3 1/2, 4, 4 1/2, and 5…

Looking-time studies examined whether 11-month-old infants can individuate two pairs of objects using only shape information. In order to test individuation, the object pairs were presented sequentially. Infants were familiarized either with the sequential pairs, disk-triangle/disk-triangle (XY/XY), whose shapes differed within but not across…

The dimensional change card-sorting task (DCCS task) is frequently used to assess young children's executive abilities. However, the source of children's difficulty with this task is still under debate. In the standard DCCS task, children have to sort, for example, test cards with a red cherry or a blue banana into two boxes marked with target…

Evidence from theory-of-mind tasks suggests that young children have substantial difficulty thinking about multiple object identity and multiple versions of reality. On the other hand, evidence from children's understanding of pretense indicates that children have little trouble understanding dual object identity and counterfactual scenarios that…

The present study tests a model of category effects upon stimulus estimation in children. Prior work with adults suggests that people inductively generalize distributional information about a category of stimuli and use this information to adjust their estimates of individual stimuli in a way that maximizes average accuracy in estimation (see…

A preference to novelty paradigm used to study human infants (Quinn, 2002) examined attention to novel animal pictures at subordinate, basic and superordinate levels in tamarins. First, pairs of pictures were presented in phases, starting with a monkey species (subordinate level) and ending with mammal and dinosaur sets (superordinate levels).…

Tool use is central to interdisciplinary debates about the evolution and distinctiveness of human intelligence, yet little is actually known about how human conceptions of artifacts develop. Results across these two studies show that even 2-year-olds approach artifacts in ways distinct from captive tool-using monkeys. Contrary to adult intuition,…

Like adults, young infants prefer attractive to unattractive faces (e.g. Langlois, Roggman, Casey, Ritter, Rieser-Danner & Jenkins, 1987; Slater, von der Schulenburg, Brown, Badenoch, Butterworth, Parsons & Samuels, 1998). Older children and adults stereotype based on facial attractiveness (Eagly, Ashmore, Makhijani & Longo, 1991; Langlois,…

Neural networks are applied to a theoretical subject in developmental psychology: modeling developmental transitions. Two issues that are involved will be discussed: discontinuities and acquiring qualitatively new knowledge. We will argue that by the appearance of a bifurcation, a neural network can show discontinuities and may acquire…